262/ EECD OVERDUE FINES: 25¢ per W per ite- RETUMIN LIBRARY MATERIALS: Place in book return to remove charge frat circulation records A C(MPARISON OF FRACTIONATED REACTION TIME AND MOVEMENT TIME IN MALES ACROSS SELECTED AGE AND PHYSICAL ACTIVITY LEVELS By Ardavan E-Lotfalian A DISSERTATION Submitted to Michigan State University in partial fu1fillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Health, Physical Education and Recreation 1981 GUS xxx- ABSTRACT A COMPARISON OF FRACTIONATED REACTION TIME AND MOVEMENT TIME IN MALES ACROSS SELECTED AGE AND PHYSICAL ACTIVITY LEVELS By Ardavan E-Lotfalian The purpose of this investigation was to compare the frac- tionated reaction time and movement time performance of 120 male subjects across various age and physical activity levels. The subjects were divided into six groups according to age and level of activity. Two young groups included men 20 to 30 years of age, two middle age groups were comprised of men ranging in age from 40 to 51 years and two older age groups were made up of men between 58 and 79 years of age. The apparatus used consisted of a stimulus unit, a response unit and a recording unit. The stimulus unit was composed of three white lights which were used as the visual stimuli. The recording unit consisted of an oscilloscope and an electromyograph. The re- sponse unit consisted of two parts, a hand response unit and a foot response unit. Following the three practice trials, each sub- ject completed a total of 48 trials including 12 hand simple, 12 hand choice, 12 feet simple, and 12 foot choice reaction time trials. Ardavan E-Lotfal ian The data were analyzed by multivariate analysis of variance procedures to detect significant differences in the performance of the three age groups or the two activity groups on total reaction time, premotor time, motor time and movement time. Analysis of the data indicated that age generally was a significant factor in total reaction time (i.e., hand simple, hand choice, foot simple and foot choice reaction time), in premotor time, in motor time associated with foot choice reaction time and in movement time. Active males and less active males were not significantly differ- ent from each other in terms of total reaction time, premotor time, motor time or movement time. Similar results were obtained when all sixteen reaction time variables were included in one analysis or'when they were analyzed in four sets of related vari- ables. To my wife Farideh, my mother, and in memory of my father 11' ACKNOWLEDGMENTS I sincerely wish to express my thanks and appreciation to my committee chairman and academic advisor, Professor John Haubenstricker, for his invaluable assistance in the planning and preparation of this dissertation. I am deeply indebted for the tremendous amount of time he devoted to all phases of this research from the beginning to the end. His counsel and inspiration were valuable in my academic devel- opment as well as for my life. No words can express my gratefulness to him, but I shall remain ever grateful for his encouragement and advice. I also would like to gratefully acknowledge the contribution of the other members of my committee, Professor Vern Seefeldt, Pro- fessor William Heusner, Professor Philip Reuschlien, Professor Peggy Riethmiller, and electrical engineer Mr. Robert Hells. They offered many suggestions and constructive criticisms to improve the quality of this study. I am particularly obligated to Professor Seefeldt for many tel- ephone calls he made in recruiting subjects, and to Professor Heusner for his guidance in the statistical design of the study. Special thanks and sincere appreciation are expressed to Mr. Wells for his helpful assistance in the construction of the appara- tus; and to Mr. Khalil Elaian for his assistance in analyzing the data. Finally, appreciation is expressed to the people who willingly participated as subjects in this study. TABLE OF CONTENTS LIST OF TABLES ........................ LIST OF FIGURES ....................... Chapter I. INTRODUCTION ..................... Statement of the Problem .............. Hypotheses ..................... Need for the Study ................. Research Plan ................... Limitation of the Study .............. Definition of Terms ................ II. REVIEW OF THE LITERATURE ............... Age Differences in Reaction Time and Movement Time . d Age Related Studies ............... Developmental Studies .............. Preparatory Interval ............... Perceptual Difficulty .............. Stimulus Intensity ................ Stimulus Alternation Versus Stimulus Repetition. . Physiological Conditioning ............ The Relationship of Physical Activity to Reaction Time and Movement Time .............. Physical Training ................ Active Versus Non-Active ............. Body Composition ................. Physical Stress ................. Fractionated Reaction Time ............. Central Versus Peripheral Processing ....... Muscular Tension and Exercise Regimen ...... Summary ...................... EXPERIMENTAL METHOD ................. Subjects ...................... Testing Environment ................ The Apparatus ................... Testing Procedure ................. Statistical Design ................. iv SOC» \l mmbwmm Chapter IV. RESULTS AND DISCUSSION ................. 67 Results ....................... 67 Descriptive Statistics ............... 68 Inferential Statistics ............... 77 Age and Reaction Time .............. 78 Activity and Reaction Time ............ 92 Discussion ...................... 95 Total Reaction Time and Movement Time ....... 95 Fractionated Reaction Time ............. 98 V. SUMMARY, CONCLUSION AND RECOMMENDATIONS ........ 100 Summary ....................... 100 Conclusions ..................... 102 Recommendations ................... 103 APPENDIX A .......................... 106 APPENDIX B .......................... 109 APPENDIX C .......................... 112 BIBLIOGRAPHY .......................... 114 .10 .11 LIST OF TABLES Distribution of subjects by age and physical activity level ..................... 58 Means and standard deviations for the fractionated hand reaction time and movement time scores ...... 69 Means and standard deviations for the fractionated foot reaction time and movement time scores ...... 70 Pearson correlation coefficients between the various measures of reaction time and movement time ...... 76 Multivariate analysis of variance for age effects on sixteen measures of reaction time and movement time. . . 79 Multivariate analysis of variance for age effects on each set of four measures of reaction time, premotor time, motor time and movement time ........... 80 Planned comparison test between young males and older males on sixteen measures of reaction time and movement time .............. . ............ 83 Discriminant function analysis of sixteen reaction time and movement time measures in contributing to performance differences between young males and older males ......................... 84 Planned comparison test between young males and older males on each set of four measures of reaction time, premotor time, motor time and movement time ...... 86 Discriminant function analysis applied to each set of four measures of reaction time, premotor time, motor time and movement time for young males and older males . . . 87 Planned comparison test between middle age males and older males on sixteen measures of reaction time and movement time ..................... 89 Planned comparison test between middle age males and older males on each set of four measures of reaction time, premotor time, motor time and movement time . . . 90 vi 4.12 4.13 Discriminant function analysis applied to each set of four measures of reaction time, premotor time, motor time and movement time for middle age males and older males .................... 91 Multivariate analysis of variance for activity effects on sixteen measures of reaction time and movement time . . 93 Multivariate analysis of variance for activity effects on each set of four measures of reaction time, premotor time, motor time and movement time .......... 94 vii 3.1 3.2 4.1 4.2 4.3 4.4 LIST OF FIGURES The apparatus for measuring reaction time and movement time: A. Stimulus unit; 8. Hand response unit; and C. Foot response unit ................... Sample record of simple-foot reaction time and movement time: A. Deflection line for stimulus and Microswitch events, 8. Electromyogram ............... Mean performance of active and less active males on hand simple reaction time and movement time measures . . Mean performance of active and less active males on hand choice reaction time and movement time measures . . Mean performance of active and less active males on foot simple reaction time and movement time measures . . Mean performance of active and less active males on foot choice reaction time and movement time measures . . viii 61 71 72 73 74 CHAPTER I INTRODUCTION The relationship between reaction time, movement time and age is curvilinear in nature. Studies show that reaction time improves with age until the end of the second decade of life; that little deterioration occurs during the third, fourth and fifth decades; and, that a gradual decline is observed beginning with the sixth decade of life (Hodgkins, 1962; Panek, Barrett, Sterns & Alexander, 1978). Unfortunately, the physiological condition of the subjects in these investigations has been largely ignored. Some significant questions regarding the role of physical fit- ness, physical activity, age, and neuromuscular efficiency were raised by Botwinick and Thompson in 1968. These investigators were concerned with the relationship between the life history of indivi- duals and their aging patterns. They assured that athletic partici- pation resulted in age differences in neuromuscular parameters. Although Botwinick and Thompson (1968) raised these important ques- tions, they failed to include an elderly, active group in their study. Therefore, further investigation is needed to determine the effects of chronic physical activity on the maintenance of neuro- muscular integrity. Tbtal reaction time is not a reliable indicator of central nervous system functioning in regard to aging and physical activity 1 levels (Clarkson, 1978) because total reaction time does not provide separate information about central nervous system and muscle con- traction functions. The current study employed an electromyographic technique in order to fractionate total reaction time into premotor time and motor time components, thus making it possible to differen- tiate between nervous system and muscular system functioning. Statement of the Problem The purpose of this investigation was to compare the frac- tionated reaction time and movement time performances of male sub- jects across various age and physical activity levels. More speci- fically, this study was designed to compare the fractionated simple reaction time of the hand and foot, the fractionated choice reaction time of the hand and foot, as well as the movement time of the hand and foot for six groups of male subjects. The six groups repre- sented: (1) young active males; (2) young less active males; (3) middle age active males; (4) middle age less active males; (5) older active males; and, (6) older less active males. Hypotheses Three hypotheses were tested in this investigation: 1. For both active and less active groups, there is a deter- ioration in reaction time and movement time performance with advancing age. 2. Differences in total reaction time between the various age groups are due to a lengthening of the premotor time component rather than the motor time component. 3. There is less deterioration in reaction time and movement time responses with advancing age in individuals who engage in a regular program of physical activity than in individuals who were formerly active or were never involved in a regular program of physical activity. Need for the Study Psychologists and physical educators are interested in the slowing of reaction time in the later years of life, not only be- cause of its importance in perceptual-motor skills, but also because of its presumed reflection of central nervous-system functioning (Botwinick, 1965). Weiss (1965) demonstrated that the increase in simple reaction time occurred predomfinantly in the premotor compo- nent of reaction time, which suggested that the greatest detrimen- tal effects of aging are found in the nervous system, rather than in the muscular system. Several studies have indicated that active elderly persons who participate in physical activity training programs have reaction time and movement time performance scores superior to those of their less active counterparts (Botwinick & Thompson, 1968; Spirduso, 1975; Spirduso and Clifford, 1979; Clarkson, 1978). For example, Spirduso (1975) found that elderly people who maintain an active life style reacted and moved significantly faster and more consistently than elderly non-active people. Even more impor- tant, they reacted and moved at least as quickly as young, non- active individuals. Conflicting results have been obtained when different age groups were compared on total reaction time and fractionated reac- tion time. Kroll and Clarkson (1977) demonstrated that on total reaction time performance, an old inactive group had the longest reaction time followed by an old active group, a young inactive group and finally a young active group. However, when reaction time was fractionated into premotor time and motor time components, members of the old active group and the old inactive group were significantly different from each other in premotor time only. Moreover, the old active group was similar to the young active group in the premotor time and motor time performance. Therefore, Kroll and Clarkson suggested that the utilization of total reaction time as a single criterion measure of the aging process fails to reveal significant differences in the components of reaction time performance. By fractionating reaction time into premotor and motor time components, nore information is derived on the functioning of the central nervous system versus that of the peripheral processing system. To this author's knowledge, no study has focused on frac- tionated choice reaction time involving the lower limbs with the performer in a standing position. Nor has total body movement time been measured for three different age groups wfith two different levels of exercise. . Research Plan The subjects were 120 male volunteers. They were categorized into six groups, 20 in each group, according to age and level of activity. The younger age groups included men 20 to 30 years of age, while the middle age groups and older groups ranged in age from 40 to 51 years and from 58 to 79 years, respectively. The active groups included men who had been involved in physical acti- vity on a regular basis all of their lives. Less active groups in- cluded men who did not exercise regularly or who had not partici- pated in regular physical activity for five years or longer. The testing apparatus consisted of a stimulus unit, a response unit, and a recording unit. The stimulus unit was composed of three white lights which were used as the visual stimuli. The recording unit consisted of a digital oscilloscope and a chart recorder with equiva- lent paper speed of 100 millimeters per second for the foot and 200 millimeters for the hand, respectively. The response unit consisted of two parts, a hand response unit and a foot response unit. The hand response unit included one releasing hand reaction time button and three hand Microswitches placed 25 centimeters apart. The foot response unit was composed of one releasing fbot reaction time but- ton and three foot switches placed 30 centimeters apart. At the light stimulus, the subject moved his hand or foot from the reaction time button to the appropriate Microswitch with the greatest possible speed. Following a brief practice period, the subject completed 12 consecutive trials fer each of the four reaction time tasks. Multi- variate analysis of variance was used to analyze the data that were collected by the above procedure. Limitations of the Study This study was subject to several limitations. First, the subjects were volunteers from Michigan State University and the immediate surrounding community. The degree to which these volun- teers were representative of the university community or that of the general population would determine the extent to which the re- sults could be generalized. Secondly, the classification of sub- jects into "active" and "less active" groups within each age cate- gory was based on a self-report activity history. The accuracy of these reports was contingent on the validity of the recall as well as the integrity of the subjects. A third limitation was the inability to secure a group of sedentary subjects. Although the attempt was made, it was not pos- sible to obtain a sufficient number of subjects at each age level who would report themselves as being sedentary. Fourth, the active subjects in this study engaged in different sport activities, there- fore, application of the results to a particular sport is not war- ranted. Finally, the electrodes for obtaining the premotor time measure for the foot were attached to the hamstring muscles. The extent to which activity recorded from this site is not an accurate measure of true premotor time for the various directional movements of the foot should be considered a limitation. Definition of Terms Reaction Time. The interval of time which elapses between the presentation of a stimulus that requires a muscular response and the onset of that response. Movement Time. The time required to move the dominant hand 25 centimeters in one of three forward directions or the dominant foot 30 centimeters in a forward, sideward, or backward direction. Simple Reaction Time. The time required for a subject to re- act to a specified stimulus with a prescribed response. Choice Reaction Time. The time required for a subject to re- act to stimuli presented randomly with the corresponding prescribed responses. Premotor Reaction Time. The period of time from stimulus on- set to the appearance of a muscle action potential from the muscle responsible for initiation of the response (Fig. 3.2). Motor Reaction Time. The duration of time from initial muscle firing to the release of the hand or foot from the reaction time button. This measure was obtained by subtracting premotor time from total reaction time. UMBERII REVIEW OF THE LITERATURE This study was designed to investigate fractionated reaction time and limb movement time in male subjects grouped according to age and level of physical activity. Since the literature on reac- tion time is voluminous, this review of the literature will be limi- ted to those studies which are central to the purpose of this inves- tigation. Thus, studies that primarily focus on the relationship of sensory modality, stimulus intensity, intelligence, academic achieve- ment, sex differences, and special populations to reaction time are not included in the review. The chapter is divided into three major sections as follows: (1) age differences in reaction time and move- ment time; (2) the relationship of physical activity to reaction time and movement time; and (3) studies specifically involving frac- tionated reaction time. Age Differences in Reaction Time and Movement Tine Speed of reaction in relation to age has been one of the most extensively studied phenomena in the laboratory investigation of human performance. One of the most reliable and well-documented findings in the literature on age and performance is that the time required by mature adults to perform nearly all activities increases with advancing age. The results of most studies which used subjects across different age spans, from early childhood through the ninth decade, conclusively demonstrated that a significant relationship exists between reaction time perfornance and chronological age. Significant relationships between chrononological age and movement time scores also have been established in many of the investiga- tions. The review of literature involving age differences in reac- tion time and movement time will be presented under the following subheadings: (1) age related studies; (2) developmental studies; (3) preparatory interval; (4) perceptual difficulty; (5) stimulus intensity; (6) stimulus alternation versus stimulus repetition; and (7) physiological conditioning. Age Related Studies Numerous investigators have studied the nature of the rela- tionship between age and reaction time performance across several decades of life. Of interest has been the determination of the age of maximum performance, the age of greatest consistency in perform- ance, and the age of onset of significant decline in reaction time performance. The curvilinear relationship of reaction time and chronological age is well docunented. In general, investigators report that re- action time improves from birth until approximately twenty years of age, at which point it plateaus for several decades and then de- creases as age increases (Bellis, 1933; Pierson, 1957; Mendryk, 1960; Hodgkins, 1962). Bellis (1933) studied the reaction time of 150 males and females sampled at random and ranging in age from 4 to 60 10 years. He obtained the shortest reaction time scores from subjects between the ages of 21 and 30 years, with a decrease in performance in the younger and older aged subjects. Pierson (1957) studied the reaction time and movement time of 400 male subjects between the ages of 8 and 83 years. He found that both movement time and reaction time were significantly related to chronological age. The fastest movement time and reaction time perfbrmances were obtained from men 19 and 20 years of age. However, the greatest stability of indivi- dual movement time and reaction time performance resulted from men 26 through 30 years of age. Junior high school boys and middle age men were found to be slower than college males in both speed of movement and reaction time in a study conducted by Mendryk (1960). He tested three groups of 50 males who were 12, 22 and 48 years of age. Measures were taken of reaction time performance and of movement speed for a short arm-thrust as well as for a longer arm movement involving a circular component. Fifty trials were completed by each subject with the short movement, followed by 60 trials with the long movement. Only the last 30 trials of each movement were analyzed. The lZ-year-old subjects were 15 percent slower than the 22-year-old males in both reaction time and the short movement time, and 7 percent slower in the long movement time. The 48-year-old subjects were 13 percent slower than the group of 22-year-old subjects in reaction time, 18 percent slower in short movement time and 21 percent slower in long movement time. All of these differences were significant with the exception of the 7 percent difference involving the long movement. 11 There were no significant differences between the performance of 12- year-old and 48-year-old subjects on any of the measures. Hodgkins (1962) examined the influence of age on speed of reac- tion and speed of movement in 480 girls and women ranging from 6 to 84 years of age. In addition, he investigated the relationship of reaction time to movement time. Results of the study showed that reaction time and movement time were uncorrelated at all age levels, except between the ages of 22 and 37 years. In these females, move- ment time improved with age up to age 15, remained constant to age 19, and deteriorated thereafter. In contrast, reaction time improved with age up to age 19, remained constant to age 26, and then deter- iorated with age. The general decline in reaction time performance in the later years stimulated interest in the existence of this phenomenon in other speed-related activities. Salthouse (1976) studied the age- performance functions for a variety of speed activities in order to determine if all activities decline at the same rate. The procedure consisted of extracting relative performance measures from five pub- lished reports that provided data on a variety of activities ranging from simple reaction time to long distance running events. Salt- house determined the maximum performance fer each set of data across all age groups and then computed ratios of performance for each age group to this maximm perfornance. He found that the steepest age declines are exhibited in the running events. These require approxi- mately 35 to 40 percent more time to complete at age 60 than at age 20. Moderate age declines were evident in the swiftness-of-blow, 12 manual-reach-and-grasp, and reaction time plus motor time activities which are performed approximately 15 to 20 percent slower at age 60 than at age 20. Simple reaction time tasks were performed only 5 percent slower at age 60 than at age 20. Another interesting find- ing of this study was that the nature of the age function was nearly identical fer running events of various distances. For example, there was no indication that age of maximum performance increased wdth distance, or that speed deteriorated more slowly at longer dis- tances than at shorter distances. He concluded that it is inappro- priate to refer to the "slowing wnth age" phenomenon without specify- ing the particular activity with which one is concerned. The differential effects of aging on many reaction time tasks become evident during the late forties and early fifties. However, fer simple tasks the aging effects may be delayed until the sixties or even beyond. Panek, Barrett, Sterns and Alexander (1978) selected 175 fenole volunteers in order to investigate age differences in perceptual-motor reaction time for seven age groups. The age of the subjects ranged from 17 to 72 years. Perceptual-motor reaction time was measured by two levels of tasks: simple choice reaction time and complex choice reaction time. The stimuli for the simple choice reaction time task consisted of four different signals--a green left turn arrow, a red braking disc, a green right turn arrow and a yellow disc for a horn-blow response. Each stimulus was presented six times in random order, to which the subject was to respond appro- priately. In the complex choice reaction time task, the stimulus consisted of a photograph of an actual driving scene in which a 13 signal or sign was embedded. Subject responses were the same as those for the simple choice reaction time task. Results of the simple choice reaction time task showed significant differences among the groups. In addition, a trend analysis yielded a signifi- cant linear trend. Newman-Keuls analysis indicated that Group 7 (age 65 to 72 years) was significantly slower than the six other groups. Analysis of the complex reaction time scores indicated that there also was a significant linear trend. Newnan-Keuls analy- sis revealed that Group 2 (age 25 to 32 years) was significantly faster than all other age groups and Group 7 (age 65 to 72 years) was significantly slower than the other groups. Groups 1 (age 17 to 24 years), 3 (age 33 to 40 years) and 4 (age 41 to 48 years) were significantly different from each other, but were significantly slower than Group 2 (age 25 to 32 years) and significantly faster than Groups 5 (age 49 to 55), 6 (age 57 to 64 years) and 7 (age 65 to 72 years). Moreover, Groups 5 (age 49 to 56) and 6 (age 57 to 64) were not significantly different from each other, but were sig- nificantly faster than Group 7 (age 65 to 72 years) and significantly slower than the other groups. Nebes (1978) studied vocal response versus manual response as a determinant of age difference in a simple reaction time task. In the two studies reported by Nebes, the type of motor response that the subjects made determined whether or not a significant difference in simple reaction time was found between young subjects and older subjects. In the first study, there was no difference between 20 older subjects and 20 younger subjects in the speed with which they 14 initiated a vocal response to a stimulus. In the second study, sim- ple visual reaction time was measured in 32 young subjects and 32 older subjects using both manual and vocal responses. With the manual response, the typical age difference in reaction time was fbund. How— ever, with the vocal response, there was no significant difference between two age groups. Thus, Nebe's findings did not support the hypothesis that with age there is a universal slowing in all cogni- tive operations. Instead, he suggested that whatever the underlying causes for behavioral slowing with age, they do not appear to operate at such a fundamental level that all psychological processes are necessarily affected. In addition, he concluded that the existence of a significant age difference in sinple psychomotor latency is dependent on the nature of the subject's response. Developmental Studies Several investigators have studied the nature of reaction time performance during the course of growth and development of children (Phillip, 1934; Goodenough, 1935; Jones, 1937; Surwillo, 1971; Sur- wflllo, 1972; Carron & Bailey, 1973; Fulton & Hubbard, 1975; Eckert & Eichorn, 1977). A01 of these investigators demonstrated a signifi- cant releationship between reaction time and development. The nature of this relationship is an improvement in reaction time with increas- ing age. This reduction in reaction time during the developmental years was revealed in both cross-sectional and longitudinal studies. In a cross-sectional study, Surwillo (1971) investigated sim- ple auditory reaction time and choice auditory reaction time tasks in a group of 110 boys aged from 46 to 207 months. Electroencephalograms 15 were recorded during performance of simple reaction time and choice reaction time to determine the extent to which differences in reac- tion time associated with development could be identified by develop- mental changes recorded in the electroencephalograms. In the simple reaction time task, ten high and ten low tones were presented in random order over an 8—minute interval. For the choice reaction time task the subject was instructed to press the reaction key only to the high tone and to ignore the low tone. As in the simple reac- tion time, ten high and ten low tones were presented in random order. The results showed a significant relationship between reaction time, standard deviation of reaction time and development. The Pearson productqmoment correlation coefficient of -.501 between age and electroencephalogram period was significant. Choice reaction time performance scores showed a more rapid decline with increasing age than those for simple reaction time. In another cross-sectional study Surwillo (1972) tested 12 boys aged 8.5 to 17 years to discover whether reaction time changed with age in children. The score fer each subject was an average value based on 20 trials of the reaction time task taken after the subject had been given ample practice. The correlation coefficient of -.895 between reaction time and age suggested that reaction time improves with age in children. The results of this investigation were sup- ported by the work of Fulton and mbbard (1975). These investiga- tors measured the reaction time and movement time of the four limbs in children at ages 9, ll, 13, 15 and 17 years. The subjects were random samples of 50 children in each age group. Fulton and Hubbard 16 reported that reaction times and movement times decreased rapidly with age. A longitudinal study by Carron and Bailey (1973) examined pos- sible changes and individual differences in the reaction time and movement time performance of 146 young boys across the age range from 7 to 13 years. Hand reaction time, movement time and body reaction time data for boys were obtained annually as part of the Saskatchewan Child Growth and Development Study. The subjects were measured for seven years (from ages 7 to 13 years) for hand reaction time and movanent time, and also fbr four years (from ages 10 to 13 years) for body reaction time. Carron and Bailey concluded that total body reaction time decreased steadily as a function of age over the age range examined. Hand reaction time steadily decreased as a function Of age from 7 to 11 years of age, but beyond this no further improvement occurred. Hand movement time decreased steadily with age from 7 to 9 years of age beyond which no further improve- ment occurred. The year-to-year correlations for hand reaction time were generally low, but statistically significant, while those fer hand movement time and body reaction time were even lower and mostly non-significant. Eckert and Eichorn (1977) examined the reaction time of two groups of children in the longitudinal studies at the Institute of Human Development, University of California Berkeley. The pur- pose was to determine developmental variability in reaction time. Group One was tested for reaction time at yearly intervals from age 4.5 to 11.5 years. The number of subjects tested at various 17 age levels ranged from 18 to 26 for girls and from 22 to 30 for boys. Group Two was measured on reaction time annually fer four consecu- tive years. The ages at testing ranged from 10 thrbugh 16 years, and the numbers at these ages ranged from 15 to 75 for boys and from 13 to 89 fbr girls. The data were grouped by chronological age and sex and by skeletal age and sex for both groups. The results for Group One indicated that there was a consistent and significant improvement in mean reaction times from 4.5 to 11.5 years fer both males and females. However, adjacent year comparisons indicated that significant improvement occurred only between ages 4.5 and 5.5 and between 5.5 and 6.5 years for both males and females. Similarly, in Group Two, there was a significant improvement in reaction time from 10 to 16 years for males using either hand. But, only between 11 and 12 years was there a significant annual increment for both hands. There was also a decline in the amount of improvement that occurred with increasing age. The females also showed significantly faster reaction times with increasing age using either the right or the left hand; but again, only between the ages of 11 and 12 years was there a significant annual improvement. However, by age 16, the mean performance had regressed to a level of performance conparable with that at 12 years of age. When the reaction time data were ana- lyzed in terms of skeletal age, significant results were obtained for both males and females. 0n the basis of skeletal age, the mean reaction time for males decreased steadily from age 8 through 16 years. In contrast, mean reaction time for females decreased only 18 from skeletal age of'8 years through 11 years, followed by trends toward increased mean reaction time. Preparatory Interval Preparatory set is, inferentially, a readiness to respond to the appropriate reaction signal. Operationally, it is measured as the variation in reaction time which occurs as a fUnction of varia- tion in the preparatory interval. The preparatory interval is the interval between the onset of the warning signal and onset of the reaction time signal. It is also commonly referred to as the fOre- period. There are two corrmon methods of using the preparatory inter- val in studies involving preparatory set. These are known as the "regular" and "irregular" procedures. In the "regular" series the length of the preparatory interval remains constant for each trial in the series. In the "irregular" series, the length of the prepara- tory interval is variable. The difference in reaction time performance under short and long preparatory interval conditions is greater for older subjects than for younger subjects (Simon, 1968; Thompson & Botwinick, 1968; Elliott, 1970). Simon (1968) conducted an experiment to investigate the signal processing component of reaction time as a function of aging. Simon tested 24 elderly subjects between 64 and 86 years of age and 24 young subjects between the ages of 18 and 21 years. The subjects were instructed to respond to two kinds of test trials, one in which the correct response was to press the key on the same side of the stimulus light and the other in which the correct response was the key on the opposite side. Two sets of warning lights were 19 used, one set positioned on top of the other. If a top warning light came on before the trial, the subject responded with the right key to the right light or the left key to the left light. If a bottom light came on before the trial, the subject responded with the right key to the left light or with the left key to the right light. All subjects performed two blocks of trials. In one block the prepara- tory interval was 100 milliseconds, and in the other block this in- terval was 1.5 seconds. Each block consisted of 60 test trials. Half of the subjects in each age group performed the short prepara- tory interval trials first while the other half performed the long preparatory interval trials first. Analysis of the data revealed that reaction time associated with the short preparatory interval was slower than that with the long preparatory interval. Simon naintained that the difference between reaction times under short preparatory intervals and long preparatory intervals provides a measure of time spent processing the meaning of the warning signal. He reported that the difference in reaction time between the short preparatory interval and long preparatory interval conditions was greater for the older group than for the younger group. Thompson and Botwinick (1968) studied age differences in rela- tion to electroencephalogram arousal and reaction time. The sub- jects included two age groups: an elderly group consisting of 16 men and 10 women ranging in age from 67 to 87 years and a younger group consisting of 16 men and 10 women ranging from 19 to 35 years of age. Preparatory intervals of .5, 3.0, 6.0 and 15.5 seconds duration were used for both a regular and an irregular series of 20 stimulus presentations. Electroencephalogram tracings were recorded from the left parieto-occipital area during the middle reaction time trials for each of the different preparatory interval conditions. In all, electroencephalograms were obtained on 82 reaction time trials fer each subject. A resting control measurement was also obtained. The results indicated that in the regular series the greatest change in electroencephalogram amplitude occurred during the .5-second pre- paratory interval for both age groups of subjects. The electroenceph- alogram change for the older group was greater than for the younger group, but the difference between the two age groups diminished as the preparatory interval durations increased. In the irregular series fer older subjects, the maximum electroencephalogram change occurred vfith the shortest preparatory interval (.5 seconds) while for younger subjects the minimum change occurred with this prepara- tory interval. The authors reported a statistically significant age différence in reaction time, but not in the electroencephalogram measure. This led to the conclusion that electroencephalogrmn changes do not explain the slowing of reaction time in older age subjects. Botwinick and Thompson (1968) reported that older adults are more variable in reaction time than younger adults independent of the preparatory interval effect. In addition to the studies mentioned, Elliott (1970) investi- gated the effect of age and preparatory interval on the simple audi- tory reaction time of 288 subjects. There were 24 subjects at each age from 5 through 13 plus 72 young adults. Reaction time scores were obtained from both regular and irregular stimulus presentation 21 procedures. The preparatory intervals were 1, 2, 4, 8 and 16 seconds. Elliott found that children had longer reaction times than young adults and their reaction time performance was affected to a greater degree by the preparatory interval than that of the young adults. Elderly subjects fail to show an anticipatory response when the preparatory period is long. Loveless and Sanford (1974) con- ducted an experiment to relate changes in preparatory set to the slow change of cortical potential known as the "contingent negative- variation." Two groups of subjects were employed. The first group included 12 young subjects ranging in age from 20.2 to 22.7 years. The second group consisted of 12 elderly subjects who had retired or were close to the age of retirement. Five foreperiods were used, namely .5, 1.0, 3.0, 6.0 and 15.0 seconds. In the regular and ir- regular sessions, 16 trials at each fbreperiod duration were recorded. At the same time, electroencephalograms were recorded from silver chloride cup electrodes Spaced along the midline in supra-orbital, frontal, vertical, and parieto-occipital positions. Analysis of data indicated that the poor perfbrmance of elderly subjects at long predictable foreperiods is accompanied by a qualitative difference in the form of "contingent negative variation." This outcome was interpreted to be less suggestive of impaired ability to maintain a state of preparation than of difficulty in controlling a sequence of psychological processes so as to initiate preparation at an appro— priate time. Lack of vigilance plays a role in the slowing of responses which has been reported as characteristic of older subjects. 22 Surwillo and Quilter (1964) conducted a study to investigate the re- lationship of vigilance to age, and to determine whether lowered vigilance is associated with the age related slowing in reaction time. The subjects were 106 men, ranging in age from 22 to 82 years. Fifty-three of the subjects were under 60 years of age and an equal number of subjects were 60 years or older. The mean age of the young group was 43.7 years and the mean age of the older group was 71.0 years. Mackworth's Clock-Test.was used. The clock had a single black pointer, 6 inches in length. This pointer moved in discrete steps. The full circle contained 100 steps, each of which occurred once every second. At long and irregular intervals, the pointer traveled through twice the usual distance in a constant amount of time. These movements were referred to as "double jumps" and in the course of 1 hour 23 such "double jumps" were presented to each subject. The subject's task was to press a response-key as quickly as possible when he recognized a "double jump." The mean percentage of "double jumps" detected by the young group was 72.9 percent while the corresponding value for the old group was 64.4 per- cent. The difference of 8.5 percent was statistically significant, indicating that, under the conditions of this experiment, older people were less vigilant than young people. In another study, Surwillo and Quilter (1965) investigated the influence of age on the latency time of involuntary and voluntary responses to the same stimulus. Involuntary response latency was measured by the latency of the galvanic skin reflex while the latency of voluntary response was measured by reaction time performance. The 23 subjects were 132 healthy males, aged 22 to 85 years. The subjects were distributed into 3 groups: a young group ranging in age from 22 to 47 years; a middle aged group ranging in age from 48 to 67 years, and older group from 68 to 85 years of age. The performance for measuring response latency was the same as that used in an earlier study by Surwillo (1964). Results of this study supported the hypothesis that the latency of the galvanic skin reflex increases with advancing age. But the latency of the voluntary responses, as measured by reaction time performance to the same stimuli, showed no increase with advancing age. Perceptual Difficulty Several investigators have studied the relationship of reaction time with perceptual difficulty (i.e. information processing, mental rotation of figures, and choice reaction time) across various age groups. These investigators found that speed of response is also a fUnction of perceptual difficulty (Birren & Botwinick, 1955; Simon, 1968; Elliott, 1970; Surwillo, 1973; Birren, 1974; Gaylord & Marsh, 1975). Birren and Botwinick (1955) conducted a study to determine to what extent perceptual difficulty might be a variable in response time across various age groups. The subjects were 30 young indivi- duals aged 19 to 36 years and 43 elderly subjects aged from 61 to 91 years. The young subjects and elderly subjects were required to judge which of two simultaneously presented lines was the shorter. The lines were presented tachistoscopically. Each subject made a minimum of 48 judgments in a series of line pairs which differed in length from 1 to 50 percent. The subject was required to respond 24 as quickly as possible when the stimulus lines were presented by saying "right" or "left" to indicate the position of the shorter line. The vocal response of the subject operated a voice key which interrupted a chronoscope circuit. A significant difference in re- sponse time between the two age groups was fbund at all levels of stimulus difficulty. The response time of the elderly group became relatively slower than that of the younger group as the stimulus difficulty was increased. Thus, the difference in response between the young group and elderly group was 0.47 second for a one percent difference in line length compared to only 0.18 second at a 50 per- cent line length difference. The authors concluded that perceptual difficulty can contribute to the slower response time of elderly subjects, but that there is a residual age difference in response time which exists regardless of ease of the perceptual task involved. Old age is accompanied by an increase in information process- ing time. Surwillo (1973) tested 54 male subjects, aged 34 to 92 years on simple reaction time and choice reaction time tasks. The stimuli, suprathreshold 250 and 1,000 cycles per second tones of equal loudness, were presented an equal number of times at random and without warning during separate experimental sessions. In the first session, subjects perfbrmed the simple reaction time task, giving a manual response whenever either tone was presented. The choice reaction time task which fellowed required the subjects to respond only when the 1,000 cycle per second tone was presented. Sixteen simple reaction time and 11 choice reaction time trials were recorded. The results of the choice reaction time task supported 25 the hypothesis that the time required to process information in- creases with age. In a related study, Birren (1974) also reported that with advancing age individuals show a tendency toward a slow- ness in response that reflects a basic change in the speed with which the central nervous system processes information. He sug- gested that it is not the motor response or muscular strength it- self which leads to accident-prone behavior in the aged, but rather an increase in decision time and the inability of the older person to rapidly discriminate relevant from irrelevant information. Older subjects respond more slowly than younger subjects on a task which requires them to mentally rotate figures. Gaylord and Marsh (1975) compared 10 right-handed young males aged from 18 to 24 years with 10 right-handed elderly males aged from 65 to 72 years to detehmine towhat extent increases in decision time with age can be apportioned to the encoding and motor fbnctions output and to the cognitive processing aspects. Subjects were asked to judge whether pairs of perspectively drawn figures were the same or mirror images of each other. The response times of old subjects and young sub- jects to "same" pairs were compared; older subjects were shown to have a significantly greater variance. Analysis of the results for two groups indicated that the greater the degree of angular orienta- tional difference, the longer the response time. Linear regression indicated that both the Y-intercept and the slope of the line repre- sented the speed with which the subject could "mentally rotate" the two figures to test for congruence. Simple reaction time, disjunctive reaction time (choice 26 reaction time with red and green lights), and simple reaction time with alerting signals all deteriorate with advancing age. Talland and Cairnie (1961) tested speed of finger response in three groups of subjects, 20 to 40, 65 to 75, and 77 to 89 years of age, respec- tively. The measures included reaction time, disjunctive reaction time, and simple reaction time with alerting signals. Analysis of data indicated that older subjects responded significantly slower under all conditions than the younger group and that the oldest group was significantly slower than the middle age group in disjunc- tive reaction time. Alerting signals resulted in faster reaction time in the youngest group but caused delay in the older subjects. The authors suggested that this paradoxical effect may be due to one or more age connected changes in central processing. Stimulus~Intensity Studies dealing with the intensity of stimulus indicate that speed of reaction time improves as the stimulus intensity increases. In addition, older subjects are slower in responding to stimuli than their younger counterparts (Botwinick, 1971; Botwinick & Storandt, 1973; Beagley & Sheldrake, 1978). Botwinick (1971) measured reaction time of 48 subjects, in two age groups. Young adult subjects ranged in age from 17 to 22 years and elderly subjects were from 64 to 79 years of age. The purpose was to discover whether or not the elderly subjects had faster reaction times than young adults when both the strength of input and the conditions of set or expectancy are favor- able to them. There were three stimulus intensity conditions. In each of these conditions, two regular preparatory interval durations 27 were used: .5 second and 6.0 seconds. Thus reaction time was meas- ured for each of six stimulus intensity-preparatory interval condi- tions. One of the three stimulus intensities was suprathreshold, the same for all subjects with 81 decibels; the other two were threshold intensities, different in decibels fer each subject, but the same or similar in terms of reported loudness. In measuring reaction time, each subject was first presented with the 75 percent threshold intensity--.5 second preparatory interval condition, next 75 percent-- 6.0 second interval, then the 100 percent--6.0 second interval, the 100 percent--.5 second interval, the suprathreshold--6.0 second inter- val, and finally, the 81 decibe1--.5 second preparatory interval. There Were 25 reaction time trials in each intensity-preparatory in- terval condition. Non-parametric U-test and students' t-tests were carried out for each intensity-preparatory condition to determine whether elderly subjects were slower than the younger adults. The total sample of elderly subjects was slower than that of younger subjects in each of the six conditions with both types of tests. Results indicated that in all cases except those involving the two lowest-intensity stimuli, the differences in reaction time between the weaker and stronger stimulus were greater for the older subjects than for the younger subjects. Even though the differences between the two weakest-intensity stimuli were greater for the elderly group than fer the young group, these differences were not statistically significant. For the purpose of studying age differences in reaction time as a function of stimulus intensity, Botwinick and Storondt (1973) 28 selected 61 female volunteers; 33 subjects ranging in age from 18 to 22 years, and 28 subjects ranging in age from 60 to 84 years. Thirty- two trials were given to each subject with each of six different stimulus intensities: a 750 Hertz tone of 55, 60, 65, 70, 75 and 85 decibels. Reaction time trials were presented with regular pre- paratory intervals of 0.5 seconds or 6.0 seconds. The first five of the 32 trials for each series were considered practice or warm- up. The last 27 trials were treated as data trials. Results indi- cated that elderly subjects were slower than young adult subjects, and that up to the point of fairly weak stimulation (55 decibels) they were as slow in relation to auditory stimuli which were loud and easy to perceive as they were to stimuli that were more diffi- cult to perceive. When the intensity of stimulation was systenati- cally decreased, the reaction times of older subjects with a 0.5 second preparatory interval were much slower than when the inten- sity of stimulation was systematically increased. Beagley and Sheldrake (1978) tested 70 normally hearing subjects in response to clicks at 60, 70, and 80 decibels. They also reported a con- sistent lengthening of latency with reduction of stimulus intensity. Stimulus Alternation Versus Stimulus Repetition A number of studies were conducted to find the effects of frequency of presentation and repetition of stimuli on the reaction time performance of subjects in different age groups. The result of these studies revealed that individuals from different age groups responded to stimulus alternations more rapidly than to stimulus repetition (Waugh, Fozard, Talland & Erwin, 1973; Fozard, Thomas & 29 Naugh, 1976; Jordan & Rabbit, 1977). Waugh, Fozard, Talland, and Erwin (1973) measured reaction time of 203 male subjects to discover the effects of age and stimulus repetition on choice reaction time. There were 65, 57, 62 and 19 subjects in each of fbur age groups, 26 to 39, 40 to 49, 50 to 59, 60 to 79 years, respectively. Sub- jects released one key wnth the right hand upon presentation of a red light and another key with the left hand when a green light was presented. Each stimulus was presented 20 times for a total of 40 trials. Stimuli on 10 of the trials were the same as on the preced- ing trial (i.e., they were repeated stimuli); while on the other 30 trials, they were different (or alternated). Results indicated that the average choice reaction time tended to increase with age. Appli- cation of Tukey's conservative test for multiple comparisons among means reveals that only the average reSponse times of the oldest and youngest age groups differed significantly. The tendency to re- spond faster to non-repeated stimuli was statistically significant. A practice effect was observed for the alternated stimuli, but not for the repeated stimuli. Results indicated that in none of the four age groups was there a statistically significant decrease in choice reaction time over trials with repeated stimUli. In contrast, there was an overall decrease in choice reaction time to alternated stimuli fer all age groups. The decrease was statistically signifi- cant, however, only fer the three younger groups. The authors sug- gested that the predictability of a stimulus, rather than repetition of a particular response, is critical to the conventional "repetition" effect. 30 A similar study to that of Waugh et a1. (1973) was conducted by Fozard, Thomas, and Waugh in 1976. They measured the binary choice reaction times of 123 males aged from 25 to 79 years in a sequence of discrete trials in which the proportion of occasions that the same stimulus light was presented twice in succession varied from .25, .50 and .75 seconds to .75, .50 and .25 seconds over successive thirds of a sequence of 120 trials. The two stim- ulus lights were presented with equal frequency. The reason for varying the proportion of times that the same light was presented twice in succession was to determine if there were age related differences in the degree to which response speed could be altered by: (a) pre-conceived expectations for repeated or alternated events; or (b) expectations developed during the course of the ex- periment with the changing proportion of stimulus alternations. Results indicated that the average response times increased with age. Most subjects, regardless of age re5ponded more rapidly to alternated stimuli than repeated stimuli, especially in the pro- portion of the sequence that contained .75 second stimulus alterna- tions. The difference in response speed to repeated and alternated stimuli was largest in the oldest age group. Expectation of change in an uncertain stimulus sequence was as great or greater in older adults as in younger adults. The difference in average response times to alternated stimuli and repeated stimuli varied according to how frequently the two kinds of events occurred at different points in the sequence; there were no age related differences in sensitivity to those changes. 31 Contradictory results to those obtained by Fozard et a1. (1976) were reported by Jordan and Rabbit (1977). These investigators made an attempt to discover if, and how, practice, compatibility and repe- tition effects interact with age. Twelve elderly subjects and 12 young subjects were tested. Signals were either a cross or a bar (+ or -) on a red, green or amber background. This was a two-choice task and subjects were instructed to press one key'whenever a cross signal appeared and the other key whenever a bar signal appeared. The subjects were told that the colored backgrounds were completely irrelevant to the task and should be ignored. Results were analyzed into repetitions and alternations of sequences and errors made. Data were classified according to repetition of shape (cross or bar) with the sane color background, alternation of shape with the same color background, or alternation of color background. Results indicated that young subjects were significantly faster than their counter- parts in each of the response classes considered. For both young and old subjects, repeated responses were significantly faster than alternated responses. Within the two classes of repetitions, when both the relevant signal (cross or bar) and irrelevant background color were repeated, the responses were faster than when the irrele- vant component was not repeated. This alternation of the irrelevant component significantly increased the processing time for the young subjects. The increase in response time fer the old subjects, how- ever, was not significant. It was also found that later in practice, old subjects were making fewer errors than the young subjects, re- versing earlier observations. 32 Physiological Conditioning Studies investigating the relationship of physiological para- meters to reaction time have produced varied results. In these studies, attempts were made to examine the relationship of cardiac cycle, cardiovascular status, heart rate, coronary heart disease and cardiovascular symptoms to reaction time in various age groups. Reaction time is not related to cardiac cycle either in elderly subjects or in the comparison of these subjects with young adults (Botwinick & Thompson, 1968; Botwinick & Thompson, 1971; Engel, Thorne, 8 Quilter, 1972). Botwinick and Thompson tested 13 elderly subjects from 68 to 86 years of age and 31 male subjects from 18 to 22 years of age. Reaction time and an electrocardiogram were simul- taneously recorded for each subject individually. A warning signal of 0.5 second duration was presented, followed by a preparatory in- terval of approximately 1.15 seconds and then the auditory stimulus. The Rewave triggered the stimulus either immediately (zero latency), after .2 second, after .4 second, or after .6 second, according to a pre-arranged schedule. For each of the four latency conditions, which were arranged in random sequence, the results indicated that the time from the Rewave in cardiac cycle latency was not a signifi- cant factor in determining whether reaction time was fast or slow. Botwinick and Thompson not only failed to demonstrate a relationship between reaction time and time of stimulation within the cardiac cycle, but they also failed to demonstrate that age groups differed with respect to possible relationships between these two variables. Engel, Thorne, and Quilter (1972) failed to find evidence of any 33 significant tendency of individuals, or groups, to exhibit reaction times which were in any way determined by the electrical events of the cardiac cycle. They reported that reaction time was longer during expiration than during inspiration; however, this effect was most likely attributable to coincidental differences in foreperiod than to the breathing cycle itself. The relationship between cardiovascular status, age and reac- tion time performance has been studied by several investigators (Birren & Spieth, 1962; Dbrist, Howard, Sutterer, Hennis, & Murrell, 1973; Abraham & Birren, 1973; Botwinick & Storandt, 1974). Birren and Spieth (1962) studied the correlation between age, response Speed, and cardiovascular functions. Subjects were 161 healthy men between the ages of 23 and 60 years. The number of individuals in each decade was 29, 39, 65, 23 and 5, respectively. A total of 33 variables were interrelated. These included 15 different psychomotor speed measurements obtained with the psychomet. The psychomet is an instrument developed at the National Institute of Mental Health that consists of a subject's panel containing ten lights and ten keys, and an experimenter's panel on which the associations between lights and keys are programmed and the speed and accuracy of the responses are registered. The physiological measurements were: diastolic and systolic blood pressure; pulse rate befbre, immediately after, and two minutes after a standardized exercise step test; and, fasting blood sugar and serum cholesterol levels. 0f 32 possible correla- tions with chronological age, 26 correlations were significant at the one percent level. The correlations were higher between the psychological measurements and age (.59 for psychomet) than between age and the physiological measurements (.28 for diastolic blood pressure and .25 for serum cholesterol level). Birren and Spieth‘ suggested the slowness of psychomotor performance with advancing age is not a direct result of the trend toward elevated blood pres- sure in healthy men. The relationship between heart rate and somatic-activity during a reaction time task was measured in several age groups. The rela- tionship between heart rate and measures of task irrelevant somatic activity (vertical eye movements and eye blinks, chin electromyograph. and general activity) during a simple reaction time task was evalu- ated by 0brist, Howard, Sutterer, Henns, and Murrell (1973) in four groups of children and young adults. The number of subjects in each group was: 4 year olds, N = 38; 5 year olds, N = 34; 8 year olds, N = 38; 10 year olds, N = 39; adults, N = 33. The preparatory in- terval ranged from 1 second to 4 seconds. Sixty simple auditory reaction time trials were given. The first five trials were prac- tice. The results of the study indicated that deceleration of heart rate and a decrease in the several parameters of ongoing task- irrelevant somatic activities were found to coincide with the re- sponses of the adults and of the children in all four age groups. Developmental or age-related differences among these measurements were seen on three somatic measures; namely, eye movements, fre- quency of eye blink, and chin electromyograph. For these three measures, the magnitude of the phasic decrease was associated with increasing age. Such an age related phase effect was not evidenced 35 with heart rate and general activity. Large age-related differences also were found with tonic levels of heart rate, general activity, chin electromyograph, and eye movements. These tonic levels of activity decreased with age. Persons behaviorally predisposed to coronary heart disease have slower reaction time than persons who are not predisposed to coronary heart disease. Abrahans and Birren (1973) measured reaction time of 48 males aged from 25 to 59 years. Based on a Standard Situation Interview, 24 coronary-prone Type A subjects and 24 nonécoronary prone Type 8 subjects were identified. The data of analysis for each subject were the means of 50 simple reaction time and 50 choice reaction time trials. The results of this investigation showed that in the absence of clinical signs of pathology, persons behaviorally predisposed to coronary heart disease had significantly longer re- sponse latencies in both simple and choice reaction time and were disproportionally slower in choice reaction time than those persons who are not predisposed to coronary disease. Abrahams and Birren concluded that in the absence of clinical signs of coronary heart disease Type A subjects manifested psychomotor characteristics sim- ilar to persons already suffering fron the disease. They reported that perhaps psychomotor slowing existed prior to the acute onset of coronary heart disease and may be the consequence of psycho- physiological antecedents to the disease. Some cardiovascular symptoms are associated with quick re- sponse. Botwinick and Storandt (1974) studied the effect of the cardiovascular status of subjects on reaction time. They used the 36 Cornell cardiovascular self report scores which ranged from zero symptoms to 7 symptoms. These scores were categorized into two groups: a high group which included individuals with 3 or more symptoms and a low group containing those persons with 2 or fewer symptoms. The results of the analysis of variance indicated that the effect of cardiovascular symptoms, as reported on the Cornell cardiovascular check list, upon the dependent variable of reaction time was significant. Individuals with fewer cardiovascular symp- toms had quicker reaction time scores than persons with more symptoms. The Relationship_of Physical Activity to Reaction ‘Time andTMovement Time Aging individuals conmonly are observed to substantially de- crease the amount of daily physical activity in which they engage. Consequently, it is often speculated that their physical fitness levels are lower than those of younger persons. Successful parti- cipation in athletic activities also has been found to be closely related to reaction time. 'While differences in reaction time be- tween athletes and non-athletes have been feund, the exact reasons for these differences remain unknown. It is possible that reaction time, rather than being limited to a function of age, might also be a function of an individual's level of fitness. Physical Training The effects of physical training on the reaction time of indi- viduals with low fitness levels have received little attention. To the best of the author's knowledge, there is only one study which has dealt with the effects of physical training on reaction time. 37 TWeit, Gollnick, and Hearn (1963) tested 20 low fitness subjects to find whether the total body reaction time of individuals can be im- proved by participation in a strenuous physical training program. The subjects ranged in age from 17 to 21 years with an average age of 18.8 years. Total body reaction time was measured by having the subject stand on two contact plates with feet parallel. When one of the two lights appeared, the subject stepped diagonally for- ward with the foot indicated by the visual stimulus. Befbre and immediately after the training program, 20 total reaction time meas- ures were recorded for each subject. Between the initial and final testing, the subjects participated in a vigorous physical training program for six consecutive weeks. Each subject was required to attend feur of five 30-minute training sessions which were conducted Monday through Friday of each week. Approximately 50 percent of the training progrmn was devoted to a battery of vigorous exercise de- signed to develop the large'muscle groups of the body. The remaining 50 percent of the program consisted of participation in speed ball, relays, sprints, and weight training. The basic objective of the program was to improve the subject's physical fitness. Analysis of the data indicated that at the conclusion of the six-week training period, the subjects had faster total body reaction times than prior to the onset of the training program. Active Versus Non-Active There is general agreement among investigators that a life style of physical activity postpones the decrements in neuromuscular functioning that are attributed to aging (Botwinick & Thompson, 1968; 38 Gore, 1972; Spirduso, 1975; Spirduso & CliffOrd, 1978; Clarkson, 1978). Botwinick and Thompson (1968) designed a study to investi- gate the influence of age and activity on reaction time. They used 13 elderly non-active men from 68 to 86 years of age and 37 young men ranging in age from 18 to 27 years. The young men were divided into athletic and non-athletic groups. Each subject completed 120 reaction time trials. The preparatory interval was set at approxi- mately 1.0 second. Analysis of data revealed that the reaction time of the young athletic group was faster than that of the young non- active group and was also faster than that of the elderly non- active group. Botwinick and Thompson suggested that lack of exer- cise may be a factor in the slowing of reaction time with age. Un- fortunately, they failed to include an elderly active group in their research design. The influence of physical activity on reaction time and move- ment time was examined by Spirduso (1975). She conducted a study to determine whether older’men who are physically active have sig- nificantly faster simple reaction time, choice reaction time and movement time performance than older non-active men. Comparisons were also made with active and non-active young men. The subjects were 60 male volunteers categorized into four groups according to age and sports activity. The young groups included men who ranged in age from 20 to 30 years, while the older groups ranged from 57 to 70 years of age. Fifteen trials of simple reaction time and 15 trials of choice reaction time were administered, but only the last 10 trials of each measure were used in the analyses. Movement time 39 was recorded for all trials. Results indicated that in all variables except choice reaction time, the ascending order for the speed of reaction time and movement time of the groups was: young active, older active, young non-active, followed by the older non-active group. In choice reaction time performance means of both the younger groups were faster than those of the older groups. The young active group was faster than the young non-active group and the older non-active group was significantly slower than the other three groups. Spirduso suggested that vigorous sports participation was a significant factor in retarding the onset of aging. The Spirduso (1975) study was replicated by Spirduso and Clifford in 1978 and again it was shown that older men who maintain an active life style react and move significantly faster and more consistently than their sedentary peers. The gradual decline in reaction time perfbrmance as a function of increasing age nay be delayed in trained subjects. To determine if leading a physically active life has any influence on cognitive perfbrmance as one grows older, Sherwood and Selder (1979) adminis- tered visual simple reaction time and visual choice reaction tine tests to 64 male and female volunteers ranging from 23 to 59 years of age. One half of the subjects were runners involved in vigorous training programs averaging 42 miles per week. The other half of the subjects were sedentary adults. Eighty sinple reaction time and 100 choice reaction time trials were given with a variable foreperiod ranging from 400 to 100 milliseconds. The results showed that there was a gradual decline in reaction time performance in 4O sedentary adults as age increased. However, this trend was not evi- dent in the trained group. Reaction time remained constant with age within the trained group. Body Composition In spite of the fact that reaction time and muscularity are considered as two important factors for successful performance in the game of football, not many investigators have studied the relationship of reaction time to body composition. The relationship between body composition measures, reaction time and run times, at 5, 15 and 40 yards for 48 college football players was investigated by Crews and Meadors (1978). Each player's optimal playing weight was predicted and the effect of being above or below one's predicted optimal play- ing weight on reaction time and run times was evaluated. Both reac- tion time and run time were obtained during a 40-yard run. A mul- tiple timing system was designed to obtain the times at the desig- nated distances. Body composition was assessed for all subjects and Predicted Optimal Playing weight was determined using body composi- tion data of professional football players as guidelines. Negative correlations between percent fat and run times were found to increase as the distance increased. The players who weighed more than their predicted optimal weight were found to have slower reaction times (but not significant) and significantly slower run times than those players who weighed less than their predicted optimal weight. Physical Stress The relationship of reaction time in the peripheral visual field with level of physical conditioning also has been investigated 41 (Reynolds, 1976; Rotella & Bunker, 1978). Reynolds (1976) conducted a study to determine: (1) if reaction time in the peripheral visual field and size of the functional visual field were altered by aug- mented levels of physical stress while perfbrnnng on a bicycle ergo~ meter; and (2) to determine the relationship between conditioning and reaction time in the peripheral visual field during periods of physical stress. TWenty-three female volunteers between the ages of 20 and 28 years served as subjects. Eleven subjects were initi- ally evaluated as conditioned and 12 subjects were evaluated as unconditioned on the basis of'performance on a bicycle ergometer. Each subject was required to pedal a Colins Pedal Model ergometer, which monitored heart rate and pedal speed and automatically adjusted the workload so that a pre-set heart rate was achieved and maintained throughout the testing. The pre—set heart rate was 160 beats per minute. The work load differed for each subject since the desired effect was to stress the subjects uniformly. While pedaling the bicycle, the subjects were required to fix their attention on a central light. The subject's task was to keep this central light lit by pressing a microswitch on the right handlebar grip. The light was extinguished by a computer program set to extinguish the light at predetennined, unevenly spaced intervals. While the sub- ject was pedaling and concentrating on the central task, eight lights mounted perimetrically in the periphery were illuminated one at a tine in a random order established by the computer program. The subject's task was to extinguish the peripheral lights dispersed on a horizontal plane as she became aware of them by pressing the 42 Microswitch mounted on her left handlebar grip. The heart rate of the subject was monitored throughout the testing. Heart rate was recorded at 30 seconds, 1 minute, and 5 minutes after the cessation of the 12 minute exercise period. The recovery heart rate of the subject determined her classification into the conditioned or un- conditioned group. After the subject had spent sufficient time learning the task, base line data were collected. These data were the subject's re- corded reaction times for the 12-minute peripheral light program while sitting on, but not pedaling, the bicycle ergoneter. The last session was conducted wdth the subject pedaling the ergometer. Non- correlated t-tests were used to analyze base line data to determine if the groups were significantly different before the exercise por- tion of the study was begun. No significant difference was dis- covered between the grbups, thus it was concluded that subsequent significant differences would be attributed to the experimental effect. The data were divided into two parts: (1) lights responded to; and (2) lights missed. The lights responded to by the subject provided the experimenter with reaction time values. During the riding periods, there was a significant difference in reaction time between the conditioned group and unconditioned group. The mean reaction time fer the conditioned group on all lights was .635 sec- onds while that for the unconditioned group was .703 seconds. An analysis of the nfissed lights showed that there existed a signifi- cant difference between misses on the right side compared to ndsses on the left side for both groups. More light presentations were 43 nnssed on the right side than on the left side. During the riding period, the unconditioned group missed significantly more light pre- sentations than the conditioned group. On the basis of the statis- tical findings, the fbllowing conclusions were made. Reaction time in the peripheral field did not increase as a result of augmented stress. Neither did reaction time increase uniformly with augmented levels of stress. There was no narrowing of the functional visual field as a result of the exercise stress. Elderly active persons are more field independent and have faster reaction time than their non-active counterparts. Because of the relationship between the ability to attend selectively to a stimulus and the obvious utilization of selective attention in ten- nis, Rotella and Bunker (1978) selected 20 male tennis players with median age of 72.5 years who participated in the national super- senior tournament and compared the scores of these 20 male tennis players to a non-random control group of 50 volunteer subjects with a median age of 71.8 years. Each subject was tested for field inde- pendence utilizing the portable rod-and-frame apparatus, which de- termines each subject's ability to use visual and proprioceptive cues in establishing the upright in two-dimensional space. Each subject was presented a series of 8 rod-and-frame positions, rotated from right to left for a 28 degree deviation. The subject's score was the mean of deviations from 0 degrees on the eight settings of the rod. Times to respond to a stimulus were detennined for each subject on three separate measures utilizing an Athletic Perfbrmance Analyzer: simple reaction time, whole body reaction time, and total body 44 response time. Shnple reaction time was measured as the time elapsed between the illumination of a single light and the depression of a response button held in the subject's preferred hand. Whole body reaction time was the time between stimulus presentation and the subject's lifting of his body off a mat. Total body response time was the time consumed from the stimulus signal until the subject had jumped from one mat to a second mat located 3 feet directly in front of the subject. Results indicated that the superbsenior tennis players were significantly more field-independent than the control group. These findings suggested that the tennis players are more able to attend the significant elements in a visual field. The ten- nis players also exhibited faster simple reaction times and total body response time than their control counterparts. Fractionated Reaction Time In the typical reaction time experiment, it is impossible to dissociate the time required to process the stimulus from the time required to execute the response, thus, the reason for the observed age decrement cannot be determined. The recent development of a technique to fractionate total reaction time into nervous system and muscle contraction latencies shows promise as a neans fbr further studying the question of central nervous system versus peripheral involvement in reaction time perfbrnance. Moreover, by using the fractionated reaction time technique, the contribution of the pre- motor time and motor time components to the deterioration of reaction time in relation to the aging process can be quantified. Research based upon an electromyographic technique which fractionates total 45 reaction time into a premotor, or central, component and a motor, or peripheral, component has led to two different conclusions. Some of the investigations have reported that the cause of age related length- ening of reaction time is due to change in the quality of central ner- vous system processing rather than in speed of muscular contraction (Birren & Botwinick, 1955; Weiss, 1965; Kross & Clarkson, 1977; Clarkson, 1978), but others reported the involvement of both central nervous system processing and muscular contraction fhnctions in this phenomenon (Botwinick & Thompson, 1966; Botwdnick & Thompson, 1966). Central Versus Peripheral Processing The changes in reaction time associated with increasing age are not due to the length of peripheral pathways, but rather are a function of'information processing within the central nervous system (Birren & Botwinick, 1955). Birren and Botwinick (1955) compared the performance of thirty-two subjects between the ages of 18 and 36 years, and thirty-two subjects between the ages of 60 and 91 years in sinple auditory reaction time fbr the finger, jaw, and foot. The purpose of the study was to detennine if the elderly subjects showed a disproportionate slowing of fbot responses compared with those of the finger and jaw. The hypothesis was that the slowing of reaction time with advancing age was correlated with the pathway length of the peripheral nerves. The results showed that the age change in reaction time was not associated with the length of the peripheral pathways. Birren and Botwinick found, however, that the reaction times of the elderly subjects were significantly slower than those of the younger subjects. 46 Weiss (1965), in a simple auditory reaction time experiment, used irregularly ordered preparatory intervals of 1, 2, 3 and 4 seconds to test the hypothesis that the major changes in reaction time associated with the preparatory interval, motivation, and age occur in the central nervous system rather than in the periphery. The subjects were two groups ranging in age from 18 to 30 and fran 65 to 80 years, respectively. He theorized that changes in reaction time, due to motivational set or length of preparatory interval, occurred predominantly in the premotor component and were, therefore, seen primarily as central rather than peripheral phenomena. Compu- tation of comparative conduction times in the peripheral nervous system suggested that the differences obtained were largely accounted for by central nervous system functions. Other evidence suggests that elderly subjects are slower than young subjects in both the premotor and motor time components. In 1966, Botwinick and Thompson conducted an experiment to investigate components of reaction time in relation to age and sex. They seg- mented reaction time into two component parts, premotor time and motor time. Reaction time and its components were analyzed in re- lation to fbur preparatory intervals within an irregular series and a regular series. These functions were then compared among subgroups comparing elderly males, elderly females, young adult males and young adult females. Electromyograms were recorded from the extensor muscle of the responding forearm during measurement of reaction time. The time between stimulus presentation and occurrence of increasing fir- ing was the premotor time. Motor'time was reaction time minus premotor 47 time. Analysis of the data indicated that the two elderly age groups were statistically slower than their younger controls, that is, motor time, premotor time, and reaction time were slowed with advanced age when subjects responded to stimuli in either the regular or irregular preparatory interval series. Interactions between age and sex were not significant, indicating that whatever the antecedent mechanisms of the slowing process with advanced age may be, they are the same for men and women. The fact that reaction time is highly correlated to premotor time and poorly correlated with motor time supports the notion that the aging effect is more a central than a peripheral phenomenon. Botwinick and Thompson (1966) fractionated reaction time into a pre- motor time component and a motor time component based upon the dif- ference between e1 ectromyograms and finger lift responses. The sub- jects were 34 men and 20 women. The mean age of the subjects was 21.3 years and they ranged in age from 18 years to 35 years. Electro- myograms were recorded from the extensor muscle of the responding forearm during measurement of simple auditory reaction times. Fbur preparatory intervals of 0.5, 3.0, 6.0 and 15.0 seconds were used in both a regular series and an irregular series. In the regular series, 21 stimulus presentations were adnfinistered for each of the four pre- paratory intervals. The orderrwithin the irregular series was pre- arranged so that each preparatory interval duration preceded the other three preparatory intervals the same number of times. Eighty- five reaction time trials were necessary with the irregular prepara- tory intervals. Electromyograms were recorded for the middle 48 reaction times within each preparatory context. Thus, of the 21 reaction times per regular preparatory interval, electromyograms were recorded for trials 7 to 16. Similarly, the electronyograms were recorded fbr only the middle 42 reaction times within the irregular series, i.e., trials 22 to 63. The results indicated that premotor time and reaction time were highly correlated (from .87 to .96) and showed comparable variation as a fbnction of preparatory interval and type of series. Motor time was poorly correlated (from +.21 to .55) with reaction time and was independent of preparatory intervals and type of series. It was concluded that reaction time is a pre- motoric process, and probably a central one. Premotor reaction time and motor reaction time do not change as a fhnction of movement extent. Lagass and Hayes (1973) studied the effect of variations in extent of movement on fractionated reac- tion times in 18 male subjects. The mean age of subjects was 23.2 years. Subjects attended two testing sessions on separate days. At each session the subject sat with his fist placed on a Microswitch and ulnar aspect of his forearm resting on a table. The angle be- tween his arm and forearm was 155 degrees. Fractionated reaction times were recorded under two different conditions both of which consisted of simple reaction time. Task A consisted of 25 trials of a simple reaction time to a visual stimulus and involved a rapid withdrawal of the fist from its resting position on the Microswitch. The 25 trials of Task 8 were initiated in the same way as Task A but continued as rapid flexion of the forearm through a fu11 range of 140 degrees. After 90 degrees of flexion, subject's fist hit the 49 second Microswitch mounted on a freely movable hinge. Task A and B differed only in the extent of movement. Results revealed that the difference between Day 1 and Day 2 means was not significant, for the total reaction time of Task A. For total reaction time of Task 8, the large extent movement, a significant difference between Day 1 and Day 2 was found. Motor reaction time for Task A and Task 8 did not change significantly from Day 1 to Day 2. Similarly for pre- motor reaction time of Task A, no significant difference was found between Day 1 and Day 2. A significant difference was revealed, however, for the premotor reaction time of Task 8 between Day 1 and Day 2. The improvement in total reaction time for Task 8 from Day 1 to Day 2 was, therefore, due to the prenotor reaction time component, as the movement time remained constant from Day 1 to Day 2. Analy- sis of variance testing for differences between the total reaction time means of Task A and Task 8 revealed no significant differences. Analysis of the fractionated components similarly revealed that motor reaction time and premotor reaction time for Task 8 were not signi- ficantly greater than those of Task A. Finding the difference between ipsilateral premotor reaction time and contralateral premotor time was the subject of one inves- tigation. Wyrick and Duncan (1974) conducted a study to determine whether a significant difference exists between ipsilateral premotor time and contralateral premotor time. When the two ipsilateral pre- motor times and contralateral premotor times were compared, the con- tralateral (mean = 71.9 milliseconds) was significantly faster than the ipsilateral (mean = 88.1 milliseconds). The effect of trials was 50 significant and the side of body by trials interaction was also sig- nificant. Muscular Tension and Exercise Regimen It is well accepted that skilled motor performance is highly dependent upon optimun timing and coordination of muscular action. Therefore, it is important to know whether the locus of changes in reaction time as a functibn of muscular tension, activity level, and exercise regimen are more central or peripheral. Schmidt and Stull (1970) investigated the changes in motor time and premotor time com— ponents of reaction time as a function of preliminary muscular ten- sion. It was hypothesized that if increased preliminary tension shortens premotor reaction time, the locus of change was central; if increased tension shortens motor reaction time, the effect was peripheral. Subjects squeezed a hand grip device to one of 3 sub- maximal tensions of 2.2, 19.9 and 37.4 pounds, and reacted to a buz- zer by squeezing as quickly and forcefully as possible. Tbtal reac- tion time appeared to decrease slightly from pretension levels of 2.2 to 19.9 pounds and then to increase slightly from 19.9 to 37.4 pounds, with no regular pattern of change. These differences in total reaction time were not significant. Premotor reaction time- appeared to shorten between pretension levels of 2.2 to 19.9 pounds, and remained nearly constant between 19.9 pounds and 37.4 pounds, representing a mean decrease of 9 percent, which was significant. Contrary to the decrease in premotor reaction time, motor reaction time appeared to increase regularly with increasing pretension, with a mean change of 17 percent. This difference was also significant. 51 Apparently, the effect of pretension was to increase the motor re- action time and to decrease the premotor reaction time. Therefbre, the results nearly cancelled each other so that no change in total reaction time could be noted. The main conclusion was that both the central and peripheral components of reaction time changed with increasing pretension, but that they changed in opposite directions. Lags in central nervous system processing are independent of lags associated with the rate of muscular tension development. Santa Maria (1970) obtained premotor time and motor time scores from 24 male subjects using a knee flexion task. It was predicted that an increased arousal state due to proprioceptive feedback from stretched hamstring muscles would shorten premotor reaction time, while motor reaction time would shorten because of changes in muscle tension development due to alternations in the contractile components of the muscle tissue. A finger reaction time task was also included in order to determine whether other factors not related to change in the stretch of the hamstring muscles were operative. She fbund that motor reaction time decreased with increased muscle stretch and constituted 46 percent of leg reaction tine. Premotor reaction time, as well as finger reaction time, increased rather than de- creased with increased muscle stretch. The correlation coefficients between premotor reaction time and motor reaction time were nega- tive but not significantly different from zero. The mean correla- tion coefficient was equal to .25. The fact that there was no re- lationship between these two components indicated that central ner- vous system processing time and rate of tension development within 52 the local muscular system are independent processes. Simple fractionated reaction time is not a reliable indicator of the onset of muscular fatigue. Kroll (1974) assessed fractionated reaction time for knee extension while the subjects were seated on an experimental table. The study was designed to consider effects of fatigue due to muscular exercise upon reaction time. Stable fractionated reaction times from well practiced subjects were assessed before, during and after an exercise regimen designed to induce fatigue. Subjects were tested over four stabilization days. On the fifth day, six bench-stepping bouts were administered to the subjects. Each bout consisted of 1,383 kilograms per meter of work at a stepping rate of 30 steps per minute. After each bout frac- tionated reaction time was assessed. Total reaction time remained stable over the bench-stepping exercise ranging from a low of 244.9 milliseconds following bout 4 to a high of 249.6 following bout 3. The total reaction time following the last bout of bench-stepping was 247.4 milliseconds, compared to a pre-exercise baseline reaction time of 246.0 milliseconds. None of the observed reaction time dif- ferences were significant. Both premotor time and motor time demon- strated no significant changes due to the exercise regimen. Some evidence shows that total reaction time and premotor time improve from day-to-day under certain conditions. Morris (1976) measured the fractionated reaction time of 20 male college students to detenmine the effects that varying amounts of daily practice of a simple visual reaction time task following randomly presented fore- periods will have on total reaction time and its fractionated 53 components. Each subject met with the investigator on four suc- cessive days at approximately the same hour. The subjects were assigned to one of four practice groups. Subjects in Group 20 re- sponded to one set of 20 trials per day, subjects in Group 40 re- sponded to two sets of 20 trials per day, and subjects in Group 60 and 80 responded to three and four sets of 20 trials per day, re- spectively. The single visual stimulus appeared after preparatory intervals of 1, 2, 3, or 4 seconds. Separate analyses were employed for total reaction time, premotor reaction time, and motor reaction time. The analysis of total reaction time indicated significant effects for days and for preparatory intervals or set. The results for premotor time were similar to those for total reaction time in that the effect of set, or length of the preparatory interval, and the effect of day were significant. The results fbr motor time in- dicated that neither variation in level of practice nor days was significant. Similar results were obtained fbr the effect of flore- period duration. Fractionated reaction time is quite sensitive to levels of activity and the adverse effects of aging. The effects of age and activity level on simple and choice fractionated response time have been studied by Clarkson (1978). She measured the simple and choice knee extension response time of four groups of subjects: 01d Active, 01d Inactive, Young Active, and Young Inactive. Each response time measure consisted of total reaction time plus movement time. Total reaction time was further fractionated into premotor time, which represents the central processing component, and motor time which 54 represents the peripheral muscular component. All sinple and choice fractionated response components demonstrated an age-related length- ening with motor time showing the least amount of lengthening. Al- though activity level enhanced the speed of all components in aged subjects, movement time was affected to the greatest extent and motor time was affected the least. Clarkson concluded that (1) motor time is little influenced by age and level of activity and (2) the deterioration in speed of movement with age is almost com- pletely negated by activity in old active subjects. Summary On the basis of the results of previous studies the fbllowing statenents appear justified: 1. The shortest reaction times are between the ages of 20 and 30 years with decrements occurring at earlier and later years. 2. The greatest stability of individual movement and reaction times occurs between the ages of 26 and 30 years. 3. All activities do not decline at the same rate, thus it is inappropriate to refer to the "slowing with age" phenome- non without specifying the particular activity with which one is concerned. 4. Developmental studies of reaction time indicate a reduc- tion in reaction time with increasing age. 5. The decrement in reaction time performance under short to long preparatory interval conditions is greater for older subjects than for younger subjects. 10. 11. 12. 13. 14. 55 Lack of vigilance plays a significant role in the slowing of responses which is characteristic of older subjects. Perceptual difficulty contributes to the slower response time of elderly subjects, but there is a residual age difference in response time which exists regardless of the ease of the perceptual task involved. Reaction time is a function of stimulus intensity, improve ing as the stimulus intensity increases. In addition, older subjects are slower in responding to stimuli than their younger counterparts. Individuals from all age groups respond to stimulus alter- nations more rapidly than to stimulus repetition. Speed of reaction in various age groups is not related to cardiac cycle and cardiovascular status of subjects. How- ever, speed of reaction is related to heart rate, coronary heart disease, and cardiovascular symptoms. . Physical training improves the speed of total body reac- tion in young adults. ' A life style of physical activity postpones the decrements in neuromuscular functioning that are attributed to aging. In the game of football, the players who weigh more than their predicted optimal weight are feund to have slower reaction times. ‘ Reaction time in the peripheral visual field does not in- crease as a result of augmented stress. There is no narrowing of the functional visual fields as a result of 56 exercise stress. In addition, elderly active persons are more field independent and have faster reaction times than their non-active counterparts. 15. The changes in reaction time associated with increasing age are not due to the length of peripheral pathways, but rather are a function of central nervous system processes. 16. Lags in central nervous system processing are independent of lags associated with the rate of muscular tension de- velopment. The review of the literature reveals that there is limited re- search concerning the fractionated reaction time and movement time performance in relation to age and activity levels. Since the changes in reaction time associated with increasing age are not due to the length of peripheral pathways but to central nervous system processing (Botwinick, 1955; Weiss, 1965; Kroll & Clarkson, 1977; Clarkson, 1978), the possibility exists that differences in total reaction time between subjects at various ages and activity levels are due more to change in the quality of central nervous system processing than to change in speed of muscular contraction. CHAPTER III EXPERIMENTAL METHOD This study was designed to compare the fractionated reaction time and movement time performances of male subjects grouped accord- ing to age and level of physical activity. Subjects The subjects were 120 male volunteers from the University com- munity at Michigan State which included students, faculty and other university personnel. Some of the subjects were obtained through personal contact outside the main university library and in various intramural locker rooms. Others were recruited via telephone calls to university faculty and staff members and by contacting agencies for the elderly in the community. The subjects were divided into six groups according to age and level of physical activity. TWO groups included men 20 to 30 years of age, two middle age groups were comprised of men ranging in age from 40 to 51 years and two older age groups were fenmed with men between 58 and 79 years of age. The men in one group at each age level were physically very active whereas the men in the second group at each age level were physically less active. The active groups included men who had been involved in physical activity on a regular basis most of their lives and who presently run, swim or engage in other kinds of vigorous 57 58 physical activity for a minimum of 45 minutes at least three times per week. The less active groups included men who did not exercise regularly in their youth or who had stopped participating in physi- cal activity on a regular basis during the past five years or longer (See Table 3.1). Subjects agreeing to participating in the study were sent in- formation about the procedures and requirements of the study. See Appendix A for the sample of these methods. Table 3.1 -- Distribution of subjects by age and physical activity level Group Age Range Mean Age N 1. Young Active 20-30 23.5 20 2. Young Less Active 20-30 23.7 20 3. Middle Age Active 40-51 46.2 20 4. Middle Age Less Active 40-51 46.4 20 5. Older Age Active 58-79 64.2 20 6. Older Age Less Active 58-79 65.0 20 Testing Environment All subjects were tested in the same location, with the same testing equipment and by the same investigator. The testing station was part of a room that could be secured from outside disturbances and that was not subject to extreme variations in temperature and humidity. The subjects were tested individually with only the 59 experimenter and the subject present during the collection of data. Each subject was tested while in a rested condition. Half of the trials were attempted with the subject standing and the remaining trials were made with the subject seated at a table. The Apparatus The apparatus consisted of a stimulus unit, a control unit, a response unit and a recording unit. The stimulus unit was com- posed of a wooden box with three white lights mounted on the front surface, each 15 centimeters apart (See Figure 3.1A). This unit was hung on a wall in front of the subject. The control unit contained selector switches for hand/foot, stimulus choice (lights 1, 2 or 3), and stimulus delay time (1-3 seconds); a start button; a warning buzzer and circuits necessary to generate the waveforms seen in Figure 3.2 A schematic drawing of the control unit is shown in Appendix C. The recording unit consisted of a digital storage oscilloscope (Gould model OS4000/4001) and a Gilson multi-channel recorder. The oscilloscope was needed because of the very short time intervals being observed (less than 1 second). Without it, a recorder having a paper speed of 200 mm/sec and extremely fast pen response (less than 2 msec) would have been required. Both the recorder and paper costs would have been excessive. Here, the oscilloscope was used as an intermediate recording device to record and store the data in real time. For this purpose, sweep speeds of .1 sec/cm (hand) and .2 sec/cm (fbot) were used. Data were then read out of storage at a slower rate (2 sec/cm) and recorded on paper (paper speed = 10 mm/sec), 60 giving an equivalent paper speed of 200 mm/sec (hand) and 100 mm/sec (foot). Errors in paper speed were corrected via time marks at .05 second intervals superimposed on channel A (See Figure 3.2). Due to the finite sampling rate of the oscilloscope, overall system time errors were _+_ .0022 second (hand) and i .0044 second (foot). The response unit consisted of two parts, a hand response com- ponent and a foot response component. The hand response unit in- cluded one releasing hand reaction time button and three hand Micro- switches placed 25 centimeters from the releasing button and 15 cen- timeters from each other. The hand reaction time button and the three hand Microswitches were mounted on a wooden board (See Figure 3.18). The foot response unit was composed of one releasing foot reaction time button and three fbot switches placed 30 centimeters from the releasing button and from each other (See Figure 3.1C). The foot reaction time button and the three foot switches were mounted on a second board. The three stimulus lights, hand switches and foot switches were all connected to the control unit. When the start button was pressed, a buzzer sounded; following the selected delay, the appro- priate stimulus light was turned on and a baseline shift was intro- duced into both oscilloscope channels, signifying the start of total reaction time (See Figure 3.2). Release of the hand reaction but- ton or fbot reaction button in response to the stimulus light caused a second baseline shift in channel A only; this point defines the end of total reaction time and the begi nning of movement time. Con- tact with the correct hand or foot Microswitch caused a return of 61 """"" A > 14.5;cm ' o g . 0 32.?) cm - N 57 C111. ' a? ' , z o z \ : = ....\'Y \\ i I, : :21.5 c . = -----~-$ ' ' ' e-mu--,Tu,§ 25 cm. \L/ . A B i , N“ 1< ------- 51 cm.---------->i g -------- 106 cm. --—-----—->; :m’.‘ LT_ I i g : 36215". 5 j ........ ... c E 530 cm. 1:] 4122. cm 1 I 30 cm. >1; 1 : I [l : I I 1 Figure 3.1 - The apparatus for measuring reaction time and movement time: A. Stimulus unit; 8. Hand response unit; and C. Foot response unit. 62 the baseline in channel A to its original position, corresponding to the end of movement time. In addition to the timing information on channel A, an electro- myogram was recorded on channel 8 to penmit fractionation of reac- tion time. Surface electrodes were placed over the motor points of the finger extensor muscle (extensor digitorum) and the knee flexor muscles (hamstrings). The interval between the baseline shift on channel 8 and the first observed muscle potential greater than background "noise" represented premotor reaction time. Motor reaction time was obtained by subtracting premotor reaction time from total reaction time. Followfing each trial, data stored in the oscilloscope were immediately transferred to the Gilson recorder for later analysis; this analysis consisted of measuring premotor reaction time, total reaction time and movement time from the paper in millimeters with a ruler, and converting these to time values from the known (ecuivalent) paper speed. Simple reaction time and movement time were measured by the presentation of the top light on the stimulus unit. Random pre- sentation of the three lights served as the stimulus for obtain- ing measures of choice reaction time and the corresponding movement times. An example of a simple reaction time trial for the foot is presented in Figure 3.2 TestingyProcedure The subjects were scheduled for testing on a random basis according to their availability. Testing took place at various 63 TRT = Tbtal reaction time PMRT = Premotor reaction time MRT = Motor reaction time MT = Movement time l h.-----— v—-----————-——-—-— Figure 3.2 - Sample record of simple-foot reaction time and movement time: A. Deflection line for stimulus and microswitch events, and B. Electromyogram. 64 time intervals between 9:00 A.M. and 6:00 P.M. All data were col- lected during the spring and sunmer of 1980. Upon entering the testing area, the subjects were introduced to the equipment and prepared for the attachment of the required electrodes. After the electrodes were attached, the procedures for the foot reaction time tasks were explained. The subjects were placed in a standing position, with the dominant foot positioned over the releasing reaction time button. They were told to adjust their position until they could comfbr- tably touch each of the foot microswitches. The stimulus unit was hung on the wall in front of the subjects approximately at eye level. A warning signal, the sound of a buzzer, was given prior to each trial. The time between the warning signal and presentation of the stimulus was randomly varied by half second units from one to three seconds. At the stimulus of light, the subject was to move his dom- inant foot with the greatest possible Speed from the reaction time button to the appropriate foot Microswitch. For the simple reaction time task, the subject moved his feet to the Microswitch directly in front of the releasing button. On the choice reaction time task, the subject moved his foot fbrward, sideward or backward to the Microswitch designated by the stimulus light. A similar procedure was fbllowed with the hand reaction time tasks, except that the subjects were seated at a table. The hand reaction time tasks always were administered after the feat reaction time tasks so that the effects of fatigue would be minimized. Three practice trials were given to the subjects for each 65 condition (simple-foot, choice-foot, simple-hand and choice-hand) to permit them to become familiar with the equipment and procedures. Following each practice period, the subjects completed 12 consecutive trials for each condition. The 12 trials fbr choice reaction time always followed the 12 simple reaction time trials to permit a simple- to-complex progression in task requirements fer each limb. Each subject also was asked to complete a biographical form so that appropriate demographic infbrmation and activity history was obtained (See Appendix B). On the basis of this activity history,, the level of activity for each subject was determined. A pilot study was conducted during the winter term of 1980 to determine the adequacy of the procedures as well as the appropriate set of trials necessary for obtaining consistency in perfbrmance. Since no learning effects were evident after a few practice trials and the attention of the subjects seemed to wane after 12 trials, it was decided to limit the number of trials fbr each measure to twelve. Thus, a total of 48 trials including 12 simple-hand, 12 choice-hand, 12 simple-foot, and 12 choice-foot reaction time trials were obtained from each subject. The mean of each set of 12 trials was used as the) perfbrmance score of each subject fer each of the variables under investigation. Statistical Design The means and standard deviations for each of the reaction time and movement time measures were calculated. A two factor crossed design was used. The independent factors were age and activity levels, while the mean of the selected set of trials on each of the 66 fractionated reaction time and movement time measures represented the dependent variables. The data were analyzed by multivariate analysis of variance to detect any significant differences in the performance of the six groups of males on the various reaction time and movement time measures. The level of significance was set at .05. CHAPTER IV RESULTS AND DISCUSSION This study was designed to compare fractionated reaction time and limb movement time of six groups of male subjects. The six groups consisted of: (1) young active males, (2) young less active males, (3) middle age active males, (4) middle age less active males, (5) older active males, and (6) older less active males. The results portion of this chapter will begin with a presen- tation of descriptive statistics involving the perfonmance means and standard deviations of the six groups of males on specific reaction time and movement time variables, followed by Pearson product correlation coefficients between the 16 dependent varia- bles. The second section contains the results of multivariate analysis of variance (MANOVA) for significant differences between activity levels and age groups as they relate to each of the hypotheses. The discussion portion of the chapter offers a rationale for the results obtained as well as comparisons with the outcomes of previous investigations whenever appropriate. Results Six groups of male volunteers ranging in age from 20 to 79 years were involved in the study. Each subject was given three practice trials for each of the testing situations to become I 67 familiar with the procedures for obtaining the reaction time and movement time scores. Following the practice trials, each subject completed a total of 48 trials which included l2 simple reaction time trials (hand), 12 choice reaction time trials (hand), l2 simple reaction time trials (foot) and l2 choice reaction time trials (foot). These data were analyzed with Version 6.l of the Finn Multivariate Program (Finn, 1978). Descriptive Statistics The means and standard deviations for each of the reaction time and movement time measures for the hand and the fact are pre- sented in Tables 4.1 and 4.2, reSpectively. The mean values are also depicted graphically in Figures 4.l through 4.4. A general age trend is apparent when examining the graphs. Reaction time and movement time performance deteriorated most notably in the two older age groups on all l6 measures, and generally more so in the less active group. ‘ Differences between the young and middle age groups, both active and less active, are not as apparent. In general, the young active males performed better than their less active peers on the twelve reaction time measures while the reverse was true fbr the four movement time values. In contrast, the reaction time perfonn- ance of the less active middle age males (40-50) either equalled or surpassed that of the active males. 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Haze eee. _wm. _ee. wew. wee. wew. wee. eew. ewe. wew. ewe. wew. the Ampaswmv eze: em m. em m. em w. em m. em w. em .w New-eee eem-eee ~ew-ewe New-emv Aee-eee New-ewv wee weepe wee eeeeez eeee» wee weeee wee e.eeez eeee» eeee_ee> m>wpu< meme m>euu< mmeoom ws_u wcmsm>oe use weep coweuemg use; empecoeuoege ms» woe mcoeuee>mc ugwuceam new memo: . ~.¢ «Peek 70 use“ acm5m>oz u.bz we?“ coewuemw Lopez u was weep eo_uuemc cowosmce u page mama coepuemm u Haw coo. mmm. oeo. ewe. emo. ewe. Nmo. mew. eeo. «we. owe. owe. #2 Pee. one. mmo. wee. mmo. Nee. mmo. Foe. mmo. wee. mwo. mme. pm: mes. mom. mmo. New. Rec. emu. ego. com. Nmo. mum. emo. omm. was; mmo. wee. coo. mme. wee. Poe. «mo. woe. “so. “we. Pmo. mum. hm Amumoguv meo. mme. mmo. ewe. mmo. amp. see. “we. mmo. Noe. mmo. Noe. .pz Pea. NwP. ewe. mme. mmo. one. mmo. mop. mmo. amp. mmo. omp. hm: Nmo. emu. mmo. amp. mmo. map. Nmo. wew. meo. cow. Fmo. mm_. mem “no. moe. eve. nmm. mmo. cum. who. mam. moo. com. mmo. mem. «hm Ampasemv boom mm m. cm .M mm W mm .M om .M cm .W Nomummv Aemnoev Nom-omv Amnuwmv Aom-oev Nom-omw m_eeewe> wee weepe wee eeeeez eeee> wee weeee eee eeee_z eeee» m>eeu< mmmw o>ewu< mmgoum weep ucmsm>os use we?» :o_uuemw woo» wouecowuuewe 0;» wow m:o_ue_>wu ugeuceam use meow: . N.¢ m_nep 7] HAND SIMPLE A. HAND SIMPLE- TOTAL REACTION TIME — —___.___ .32: .320 .300 . 239 8 .230 (D 20— 3o 40- 50 58-79 3. HAND SIMPLE -PREMOTOR REACTION TIME .240 .236 .230 , .220 0 “J 0) mo 205 .202 ‘204 ' 203 .20I .200 T. AGE 20-30 40—50 53-79 c. HAND SIMPLE - MOTOR REACTION TIME . 090 0 D1 fll u: CI) AGE 20— 30 4o— 50 58-79 0. HAND SIMPLE -MOVEMENT TIME .200 I86 l85 .Ieo SEC. fllfll 20— 30 40- 50 58-79 D ACTIVE I LESS ACTIVE Fig. 4-I. Mean performance of active and less active moles on hand simple reaction time and movement time measures. P SEC. 0') E 0 SEC. 9 SEC. .I80 72 HAND CHOICE HAND CHOICE-TOTAL REACTION TIME .360 .340 .31le 20- 30 40- 50 58- 79 . HAND CHOICE- PREMOTOR REACTION TIME .270 - .260 - .250 - ‘5 .240 - (D .230 - .220 - L L n AGE 20— 30 40- 50 58- 79 . H_AND CHOICE- MOTOR REACTION TIM__E .090 filmfll 20- 30 40- 50 58— 79 HAND CHOICE-MOVEMENT TIME mmfll AGE 20- 30 58— 79 I: ACTIVE - LESS ACTIVE .200 Fig. 4-2. Mean performance of active and less active males on hand choice reaction time and movement time measures. SEC. CD SEC. 0 SE 0 SEC. 73 FOOT SIMPLE FOOT SIMPLE-TOTAL REACTION TIME .420 .400 .380 :3: .6531 Hi El 20- 30 40— 50 58- 79 . FOOT SIMPLE- PREMOTOR REACTION TIME .220 7 .2I0 .200 20- 30 40— 50 58— 79 . FOOT SIMPLE- MOTOR REACTION TIME .l80 — .I70 - .I66 °.Ieo - d- 1'. AGE 20—30 40— 50 58- 79 . FOOT SIMPLE-MOVEMENT TIME .200 .— .I87 .l83 .l80 ~ .l62 .I62 J54 .Iso - .l56 .I4o - i: AGE 20—30 40—50 58- 79 I: ACTIVE I LESS ACTIVE Fig. 4-3. Mean performance of active and less active males on foot simple reaction time and movement time measures. D SEC. W SEC. 74 FOOT CHOICE . FOOT CHOICE—TOTAL REACTION TIME .430 478 [ .465 .460 .440 . .427 _423 .420 - .400 _ .40I it AGE 20—30 40-50 . FOOT CHOICE-PREMOTOR REACTION TIME .300 .280 279 .277 .260 .256 .250 ‘L AGE 20 - 30 4o - 50 58 — 79 O 0 SEC. . FOOT CHOICE-MOTOR REACTION TIME .l80 .l60 I47 I48 I48 I40 .l28 .I20 1’. AGE 20-30 40—50 58-79 . FOOT CHOICE-MOVEMENT TIME .240 .220 200 l94 .l86 .l82 .I 80 .I80 I AGE 20 - 30 40 - 50 58 - 79 D ACTIVE . LESS ACTIVE Fig. 4-4. Mean performance of active and less active males on foot choice reaction time and movement time measures. II 75 There are no definite patterns in perfOrmance variability among the age groups on the various reaction time and movement time measures (See Tables 4.l and 4.2). However, the active subjects tended to be less variable on the hand tasks (14 of 24 SD values) and more variable on the foot tasks (l6 of 24 SD values) than the less active subjects. In only two instances was the direction of variability constant across a set of tasks. The older age active males were consistently less variable on the faur hand simple reac- tion time tasks (Table 4.l) and the middle age active males were consistently more variable on the four foot simple reaction time tasks (Table 4.2) than their respective contrast groups. The intercorrelation matrix for the twelve reaction time and four movement time variables is presented in Table 4.3. Total reac- tion time measures do not correlate highly with each other. Although the correlation coefficients reach the mid.706 within a limb (simple and Choice), between limb values only ranged from .52 to .64. Total reaction time correlated well with its premotor component (from .84 to .89), but less well with its motor canponent (from .58 to .83). This difference is probably due, in part, to the fact that the pre- motor conponent constitutes the major portion of the total reaction time score. The Pearson product moment correlation values f0r*movement time were moderate to higi. Intralimb coefficients were high for the hand (r = .93) and foot (r = .85) whereas interlimb relationships were noderate ranging from .66 for hand choice and fbot choice to .78 for hand simple and foot simple. It should be noted, however, 76 95...— ucwEw>O£ u h: we?» coeuuemg Logo: "hm: ween coeuuema Lowoswca u xx; ms_» coeuuemm n ma oo.p «em. Noe. mam. mmw. mom. own. emm. Pom. vow. «em. va. emu. com. pwm. mmv. #2 oo.— 5mm. awe. eve. up“. new. pom. ewe. Pom. Fae. «em. mmo. omm. ohm. mwm. hm: oo.— cam. mme. _oc. wwo. eve. New. men. oem. “—0. men. men. mac. mmm. but; oo._ ewe. mmw. owe. Non. Nam. mm¢.. ppm. “no. “mm. mam. mmm. owe. ha mu_o;u took oo.— m_m. ohm. com. «we. own. om_.. can. own. man. owm. own. #2 oo.p owm. mwm. pmc. omm. epm. own. “Km. mmm. omm. ooe. pm: oo.p mmm. own. m—m. men. Ame. mam. com. omm. pmm. para oo.p anew. Nam. mum. hem. mom. Nme. New. mam. pm measwm woo; oo._ mom. cup. omm. mmm. mmm. mom. sum. #2 co._ Nomp. mum. ooc. omk. Now. mom. pm: oo.— wew. mnp.. omp. pee. Nam. Fax; 00.. mac. mom. mom. owe. ha muwocu ecu: oo.p mam. emm. mme. p: oo.p mom. Fem. has oo.P 0mm. haze oo.— a.hm m—aemm ace: #2 ha: haze .ew #2 pm: haze km ex ex: haze ex ex ea: emzmlluwm ee_eee eeee e_eeem eeee eeeeee eeez e_eeem eee: e_eeece> wave acoaw>oe use ms_» :omuuemg Co mwsamewa maoege> mg» cmwzwwn mucmmupewwou coweepoggou acmsoa wastage cowaema i m.e m_eep 77 that the within limb movement task was the same far both the simple and choice response conditions. Relationships between total reaction time and movement time are low to slightly moderate. The coefficient values ranged from .33 between hand choice reaction time and hand choice movement time to .60 between foot simple reaction time and f00t simple movement time. In general, the coefficients between f00t reaction times and fact movement times were higher than those far the hand. More- over, the values for simple reaction time and simple movement time were higher than the coefficients for choice reaction time and choice movement time. Inferential Statistics The data were subjected to multivariate analysis of variance (MANOVA) procedures in order to examine the effect of the sixteen reaction time and movement time variables across the three age groups and the two levels of activity. All sixteen dependent variables were included in the first MANOVA. Subsequently, separate MANOVA procedures were applied to the four total reac- tion time measures, the four premotor reaction time variables, the four sets of motor reaction time scores and the four movement time variables, respectively. Follow-up procedures including planned comparisons, examination of univariate F values and dis- criminant function analysis were used when significant multi- variate results were obtained. These results are presented in terms of the three hypotheses tendered in Chapter One. 78 Age and Reaction Time. The first two hypotheses dealt with the effects of age on reaction time and movement time perfbrmance. According to the first hypothesis, a deterioration in reaction time and movement time performance would occur with advancing age for both the active and the less active activity groups. In the second hypothesis, it was postulated that such differences in reaction time across the age groups would be due to changes in the premotor component rather than in the motor component of reaction time. MANOVA procedures applied simultaneously to all sixteen de- pendent measures yielded a significant main effect far age (Table 4.4). The multivariate F statistic of 1.898 was significant with P less than .004. _Examination of the univariate F values revealed that eight of the sixteen variables were significant at the .003 level. (The .003 level was used to preserve the multivariate .05 alpha criterion.) Significant age effects were noted for two reac- tion time variables (hand choice and foot choice), two premotor time measures (hand choice and foot choice), one motor time measure (foot choice) and three movement time variables (hand simple, hand choice and foot choice). There was no significant age by activity inter- action effect. When separate analyses were conducted far each of the four sets of four variables (i.e., reaction time, premotor time, motor time and movement time) twelve of the sixteen variables were sig- nificant (Table 4.5). In addition to the eight variables identi- fied in the previous analysis, hand simple and foot simple reaction time, fbot simple premotor time and foot simple movement time 79 Table 4.4 Multivariate analysis of variance for age effEcts on sixteen measures of reaction time and movement time Variable Univariate Multivariate F P F P Hand Simple RT ** 4.610 .012 PMRT 2.818 .064 MRT 3.531 .033 MT 6.014 .003* Hand Choice RT 8.836 .0003* PMRT 7.506 .001 * MRT 2.324 .103 MT 7.318 .001 * Foot Simple RT 5.166 .007 PMRT 4.975 .008 MRT 2.782 .066 MT 5.078 .008 Foot Choice RT 15.055 .0001* PMRT 9.434 .0002* MRT 10.925 .0001* MT 9.444 .0002* 1.898 .004* Interaction 1.302 .142 (Age by Activity) Note - All Probability values were rounded to the nearest .001 unless otherwise noted. * Significant at the .05 level for the multivariate F and at the .003 level far univariate F's. **RT = Reaction time PMRT = Premotor reaction time MRT = Motor reaction time ”T = Movement time 80 'Table 4.5 Multivariate analysis of variance for age effécts on each set of four measures of reaction time, premotor time, motor time and movement time Variable Univariate Multivariate F P F P Reaction Time Hand Simple 4.610 .012* Hand Choice 8.836 .0003* Foot Simple 5.166 .007* Foot Choice 15.055 .0001* 4.601 .001* Interaction 1.480 .160 (Age by Activity) Premotor Time ' Hand Simple 2.818 .064 Hand Choice 7.506 .001* Foot Simple 4.975 .008* Foot Choice 9.434 .0002* 3.068 .0003* Interaction 1.654 .111 (Age by Activity) Motor Time Hand Simple 3.531 .033 Hand Choice 2.324 .103 Foot Simple 2.782 .066 Foot Choice 10.925 .0001* 3.367 .001* Interaction 0.827 .580 (Age by Activity) Movement Time Hand Simple 6.014 .003* Hand Choice 7.318 .001* Foot Simple 5.078 .008* Foot Choice 9.444 .0002* 2.966 .004* Interaction 0.825 .581 (Age by Activity Note - All Probability values were rounded to the nearest .001 unless otherwise noted. * Significant at the .05 level far multivariate F's and at the .012 level for univariate F's. 81 performance contributed significantly to the age effect. Reduction of the number of variables in each analysis to faur permitted a P value of .012 or less to be used as the alpha level for the uni- variate F's. However, since four MANOVAs were applied, the proba- bility of a Type I error also is greater than .05. Again, there were no interaction effects between age and activity in any of the four analyses. The results of these analyses either partially or completely supported the first hypothesis. Under the more conservative analy— sis, MANOVA.with sixteen variables, the two choice reaction time variables (hand and foot) showed deterioration with age as did three of the four movement time variables. Only the movement time associated with the feat simple reaction time task did not exhibit significant age effects (Table 4.4). when the four reaction time variables and the four movement time variables were analyzed in separate MANOVAs, all eight variables contributed significantly to the age main effect (Table 4.5), thus providing full support for the first hypothesis. The second hypothesis dealing with the two components of reaction time was partially supported by both analyses. It was hypothesized that deterioration in reaction time with age would occur’to a greater extent in the premotor’time component than in the motor time component. Only two of the four premotor time measures (hand choice and foot choice) were significant in the six- teen variable MANOVA (Table 4.4) whereas three of the faur measures were significant with the four variable MANOVA (Table 4.5). The 82 additional variable was the premotor component for foot simple reaction time. Only the foot choice motor time component showed deterioration with age. This result occurred with both analyses (Tables 4.4 and 4.5). Additional analyses were conducted to determine between which groups the changes in perfbrmance took place. Two planned compari- sons were made: (1) between the young males and the older age males; and (2) between the middle age males and the older age males. The first contrast, the young males versus the older males, was significant when all sixteen dependent variables were included in the analysis (multivariate F = 2.546, P less than .003). In- spection of the univariate F values indicated that five of the var- iables contributed the most to the age differences in perfonnance (Table 4.6). These included hand choice and foot choice reaction time, hand choice and foot choice premotor time, and feat choice motor time. The results of discriminant function analysis identi- fied the most powerful of these variables to be fact choice reaction time, fallowed in order by hand choice reaction time, foot choice premotor time, hand choice premotor'time and foot choice motor time (Table 4.7). The standardized coefficients for foot simple reac- tion time (-4.215), feat simple premotor time (2.657) and fact simple motor time (1.823) also were high, but their respective univariate F values were not significant. Therefore, the role of these variables in contributing toward the age difference in per- formance is not clear. The interaction effect far age and activity was not significant. 83 Table 4.6 Planned comparison test between young males and older males on sixteen measures of reaction time and movement time Variable Univariate Multivariate F P F P Hand Simple H RT 1.816 .180 PMRT 1.692 .196 MRT 0.681 .411 MT 5.108 .026 Hand Choice RT 10.125 .002* PMRT 10.585 .002* MRT 0.233 .631 MT 4.606 .034 Foot Simple RT 4.334 .040 PMRT 5.164 .025 MRT 1.650 .202 MT 3.827 .053 Foot Choice RT 20.676 .0001* PMRT 14.209 .0003* MRT 12.676 .001* MT 6.666 .011 2.546 .003 * Interaction 1.302 .142 (Age X Activity) Note - All Probability values were rounded to the nearest .001 unless **RT PMRT MRT MT otherwise noted. * Significant at the .05 level for the multivariate F and at the .003 level for the univariate F's. Reaction time Premotor reaction time Motor reaction time Movement time ,84 Table 4.7 Discriminant function analysis of sixteen reaction time and movement time measures in contributing to perform- ance differences between young males and older males Variable Standardized Coefficient Hand Simple Reaction lime - .002 Premotor Time - .574 Motor Time .044 Movement Time .106 Hand Choice Reaction Time 1.408* Premotor Time - .615* Motor lime - .903 Movement Time .036 Fact Simple Reaction Time -4.215 Premotor Time 2.657 Motor Time 1.823 Movement Time - .561 Foot Choice Reaction Time 2.251* Premotor Time -l.210* Motor Time - .010* Movement Time .413 Note - The magnitude of the coefficient indicates its contribution to between-group variation. * Denotes those variables whose univariate F-values were significant in Table 4.6. When the youngest and oldest age groups were compared via the four separate analyses (reaction time, premotor time, motor time and movement time), significant differences were found far the reaction time (multivariate F = 6.996, P less than .001), premotor time (multivariate F = 4.694, P less than .002) and motor time 85 (multivariate F = 4.056, P less than .004) measures, but not for the movement time (multivariate F = 1.879, P less than .119) variables (Table 4.8). In addition, there were no interaction effects. Among the univariate F's for reaction time, the ones for hand choice reac- tion time (F = 10.125, P less than .002) and foot choice reaction time (F = 20.676, P less than .0001) were significant at the .012 level and contributed most to the age difference. Of these two, foot choice reaction time performance exerted the most influence toward the difference as evidenced by the standardized discriminant function coefficient (Table 4.9). The premotor components far hand choice reaction time (F = 10.585, P less than .002) and far foot choice reaction time (F = 14.209, P less than .0003) also contri- buted significantly to the age group differences. In this case, both perfbrmance variables contributed nearly equally to the age difference. Only the motor time component for choice foot reac- tion time was significant (F = 12.676, P less than .001) in contri- buting toward the age difference between the younger and older age groups on the basis of motor time performance. There was complete agreement between the results from both the sixteen variable and the faur variable analysis with regard to the individual variables responsible for the differences between the young and older groups. The five variables most responsible for the age differences were hand and foot choice reaction time, hand and fact choice premotor time, and foot choice motor time. None of the variables associated with simple hand and simple foot reaction time were significant. These results, when considered in 86 Table 4.8 Planned comparison test between young males and older males on each set of four measures of reaction time, premotor time, motor time and movement time Univariate Multivariate F P F P Reaction Time Hand Simple 1.816 .180 Hand Choice 10.125 .002* Foot Simple 4.334 .040 Foot Choice 20.676 .0001* 6.996 .001* Interaction 1.853 .124 (Age by Activity) Premotor Time Hand Simple 1.692 .196 Hand Choice 10.585 .002* Foot Simple 5.164 .025 Foot Choice 14.209 .0003* 4.694 .002* Interaction 1.211 .310 (Age by Activity) Motor Time Hand Simple 0.681 .411 Hand Choice 0.233 .631 Foot Simple 1.650 .202 Foot Choice 12.676 .001* 4.056 .004* Interaction 0.566 .688 (Age by Activity Movement Time Hand Simple 5.108 .026 Hand Choice 4.606 .034 Foot Simple 3.827 .053 Foot Choice 6.666 .011 1.879 .119 Interaction 0.868 .485 (Age by Activity) Note - All Probability values were rounded to the nearest .001 unless otherwise noted. * Significant at the .05 level for the multivariate F's and at the .012 level for the univariate F's. 87 Table 4.9 Discriminant fanction analysis applied to each set of four measures of reaction time, premotor time, motor time and movement time for young males and older males Variable Standardized Coefficient Reaction Time Hand Simple - .532 Hand Choice .461* Foot Simple - .488 Foot Choice l.237* Premotor Time Hand Simple .570 Hand Choice — .711* Foot Simple - .074 Foot Choice ‘ - .704* Motor Time Hand Simple .223 Hand Choice - .344 Foot Simple - .628 Foot Choice 1.368* Movement Time Hand Simple - .342 Hand Choice - .189 Foot Simple , .646 Foot Choice -l.lO9 * Denotes those variables whose univariate F-values were significant in Table 4.8. conjunction with the mean performance values on each of the varia- bles (Tables 4.1 and 4.2), indicate that young males perform better than older males on reaction time tasks involving the hand and foot, particularfly those tasks which require a decision on choice to be made. The second contrast, comparing the middle age males to the older age males, failed to yield significant results when all sixteen variables were analyzed at once (Table 4.10). The multi- variate F value of 1.484 was not of sufficient magnitude to meet the .05 criterion for significance. Therefore, no further analyses were conducted. However, when separate analyses were perf0rmed on the four sets of four dependent variables (i.e., reaction time, premotor time, motor time and movement time), some differences between the middle age and older age groups were detected (Table 4.11). The multivariate F values on three of the four analyses were signifi- cant. These included reaction time (multivariate F = 2.661, P less than .036), motor time (multivariate F = 2.925, P less than .024) and movement time (multivariate F = 4.310, P less than .003). No significant interaction effects were detected in any of the analyses. Three of the measures for reaction time had significant uni- variate F values (hand simple, hand choice and fact choice). The fourth measure, foot simple reaction time, approached significance. The most powerfUl variable contributing to reaction time perform- ance differences was foot choice reaction time followed by hand simple and hand choice reaction time in descending order (Table 4.12). Three movement time variables also contributed signifi- cantly to the age effect. These included hand simple, hand choice and foot choice movement time. Discriminant function analysis iden- tified hand choice movement time as the most powerful in denoting the age difference. Foot choice and hand simple movement time also exerted strong influences. It should be noted that the P value for foot simple reaction time (.013) failed totmeet the criterion value of .012 by a mere .001 (Table 4.11). 89 Table 4.10 Planned comparison test between middle age males and older males on sixteen measures of reaction time and movement time Variable Univariate Multivariate F P F P Hand Simple RT* 7.404 .008 PMRT 3.942 .049 MRT 6.381 .013 MT 6.920 .010 Hand Choice RT 7.547 .007 PMRT 4.428 .038 MRT 4.415 .038 MT 10.030 .002 Foot Simple RT 5.999 .016 PMRT 4.786 .031 MRT 3.915 .050 MT 6.329 .013 Foot Choice RT 9.434 .003 PMRT 4.660 .033 MRT 9.173 .003 MT 12.221 .0007 1.484 .121 Interaction (Age by Activity) 1.43 .143 Note - A11 Probability values were rounded to the nearest .001 unless otherwise noted. *RT = Reaction time PMRT = Premotor reaction time MRT = Motor reaction time MT Movement time Table 4.11 Planned comparison test between middle age males and older males on each set of four measures of reaction time, premotor time, motor time and movement time Variable Univariate Multivariate F P F P Reaction Time Hand Simple 7.404 .008* Hand Choice 7.547 .007* Foot Simple 5.999 .016 Foot Choice 9.434 .003* 2.661 .036* Interaction 1.154 .335 (Age by Activity) Premotor Time Hand Simple 3.942 .049 Hand Choice 4.428 .038 Foot Simple 4.786 .031 Foot Choice 4.660 .033 1.671 .162 Interaction 2.158 .078 (Age by Activity) Motor Time Hand Simple 6.381 .013 Hand Choice 4.415 .038 Foot Simple 3.915 .050 Foot Choice 9.173 .003* 2.925 .024* Interaction 1.091 .365 (Age by Activity) Movement Time Hand Simple 6.920 .010* Hand Choice 10.030 .002* Foot Simple 6.329 .013 Foot Choice 12.221 .0007* 4.310 .003* Interaction 0.793 .532 (Age by Activity) Note - All Probability values were rounded to the nearest .001. * Significant at the .05 level for multivariate F's and at the .012 level for univariate F's. 91 Table 4.12 Discriminant function analysis applied to each set of four'measures of reaction time, premotor time, motor time and movement time for middle age males and older males Variable Standardized Coefficient Reaction Time Hand Simple - .328* Hand Choice - .189* Foot Simple .056 Foot Choice - .661* Premotor Time Hand Simple - .113 Hand Choice - .434 Foot Simple - .466 Foot Choice - .214 Motor Time Hand Simple - .561‘ Hand Choice .061 Foot Simple .225 Foot Choice - .866* Movement Time Hand Simple l.000* Hand Choice -l.332* Foot Simple .586 Foot Choice -1.l72* *Denotes those variables whose univariate F values were significant in Table 4.11. Only one of the four motor time variables, foot choice, contri- buted significantly to the performance difference between middle age and older age males. However, the F value for hand simple motor time was nearly significant (univariate F = 6.381, P less than .013). Middle age men performed significantly different fran older age men in reaction time, motor time and movement time, but not in premotor time. However, these differences were only detected when 92 the variables were clustered and analyzed separately. In each in- stance where differences were found, the middle age males performed better than the older males. Activity and Reaction Time. The third hypothesis, that there is less deterioration in reaction time and movement time responses with advancing age in individuals who engage in a regular progrmn of physical activity than in individuals who are currently less active or were formerly active, also was tested by MANOVA procedures. The performances of the two activity groups, "active" and "less active," on the sixteen reaction time and movement time variables were analyzed by the two approaches used in the previous section-- inclusion of all sixteen measures in one analysis and division of the sixteen measures into faur groups for separate analysis. An alpha level of .05 was chosen as the criterion for significance. Simultaneous inclusion of all sixteen measures of reaction and movement time failed to detect an activity effect. The multi- variate F value of 1.616 had a P value of .078 (Table 4.13). Thus, this outcome does not support the third hypothesis. However, the limitation of the procedures for classifying the subjects into activity groups warrants that final judgment concerning the effect of activity on reaction time and movement time be reserved. The results of the four separate MANOVA procedures also failed to support the third hypothesis. None of the multivariate F values for reaction time (F = .660, P less than .621), premotor time (F = 1.467, P less than .217), motor time (F = 1.428, P less than .229), and movement time (F = 1.671, P less than .162) were significant 93 Table 4.13 Multivariate analysis of variance for activity effects on sixteen measures of reaction time and movement time Univariate Multivariate Variable F P F P Hand Simple RT* 2.137 .147 PMRT 3.673 .058 MRT 0.098 .755 MT 0.193 .661 Hand Choice RT 0.445 .506 PMRT 0.937 .335 MRT 0.227 .635 MT 0.119 .731 Foot Simple RT 0.794 .375 PMRT 0.060 .807 MRT 2.640 .107 MT 0.160 .690 Foot Choice RT 0.776 .380 PMRT 0.004 .947 MRT 3.988 .048 MT 0.888 .348 1.616 .078 Interaction 1.302 .142 (Age by Activity) Note - All Probability values were rounded to the nearest .001. *RT = Reaction time PMRT = Premotor reaction time MRT = Motor reaction time MT = Movement time 94 Table 4.14 Multivariate analysis of variance for activity effect on each set of four measures of reaction time, pre- motor time, motor time and movement time Univariate Multivariate Variable F P F P Reaction Time Hand Simple 2.137 .147 Hand Choice 0.445 .506 Foot Simple 0.794 .375 Foot Choice 0.776 .380 0.660 .621 Interaction 1.480 .166 (Age by Activity) Premotor Time Hand Simple 3.673 .058 Hand Choice 0.937 .335 Foot Simple 0.060 .807 Foot Choice 0.004 .947 1.467 .217 Interaction 1.654 .111 (Age by Activity) Motor Time Hand Simple 0.098 .755 Hand Choice 0.227 .635 Foot Simple 2.640 .107 Foot Choice 3.988 .048 1.428 .229 Interaction 0.827 .580 (Age by Activity) Movement Time Hand Simple 0.193 .661 Hand Choice 0.119 .731 Foot Simple 0.160 .690 Foot Choice 0.880 .348 1.671 .162 Interaction 0.825 .581 (Age by Activity) Note - All Probability values were rounded to the nearest .001. 95 (Table 4.14). These results indicate that under the criteria used for classifying the subjects into active and less active groups, activity level had little influence on the reaction time and move- ment time performance of the subjects participating in this study. Discussion The purpose of the study was to compare the fractionated reac- tion tine and movement time performances of male subjects across various age and physical activity levels. This discussion will facus on a comparison of the results of this study with previous findings in tenns of: (1) total reaction time and movement time and (2) fractionated reaction time. Total Reaction Time and Movement Time The results of this study support the generalization that age is a significant factor in the deterioration of reaction time and movement time performance. The three age groups of young males, middle age males, and olderInales were significantly different from each other in total reaction time and movement time of the hand and foot, including both simple and choice reaction time. The literature generally supports the notion that reaction time improves with age until maturity is reached and subsequently deteriorates with old age (Bellis, 1933; Pierson, 1957; Mendryk, 1960; Hodgkins, 1962). The current investigation showed age differ- ences for both simple and choice reaction time of the hand and foot. Y0ung males were significantly faster than older males in hand choice reaction time and foot choice reaction time, but not in hand simple 96 reaction time and foot simple reaction time. Middle age males were significantly faster than older males in hand simple reaction time, hand choice reaction time, and foot choice reaction time. Middle age males performed as slow as older males in foot simple reaction time. A plausible explanation for the failure to obtain age dif- ferences between young males and older males in hand and foot simple reaction time; and, also between middle age males and older males in foot simple reaction time was the lack of perceptual difficulty in the task perfonmed. These results coincide with those obtained in the studies by Birren and Botwinick (1955), Simon (1968), Elliot (1970), Surwillo (1973), Birren (1974), and Gaylord and Marsh (1975), all of whom faund that speed of response is also a function of per- ceptual difficulty. Thus tasks with little perceptual difficulty place few demands on the central nervous system thereby minimizing the effects of age on performance. The results of the present study clearly indicated some age differences far movement time measures. These results pertain to movement time associated with hand simple reaction time, hand choice reaction time, foot simple reaction time and fact choice reaction time. Although the young males did not move faster than the older males on the four variables of movement time performance (Table 4.8), the "fiddle age males did move significantly faster than the older males (Table 4.11). These differences were present for three of the four movement time performances when analyzed by MANOVA procedures that included only the four movement time variables. However, in the sixteen variable MANOVA, the univariate F's for movement time 97 were not interpreted since the multivariate F value obtained was not significant. These results are in partial agreement with the find- ings of Bellis (1933) and Pierson (1977). Why the movement time of the young subjects was as slow as that of the older subjects is not known. Perhaps some undetected bias was operating in the process of obtaining the young male volunteers. The results of this study failed to show a significant differ- ence between active and less active males on any of the faur total reaction time measures. Active males also did not move faster than the less active males on any of the movement time variables. These results are contrary to the findings of other investigators (Botwinick & Thompson, 1968; Spirduso, 1975; Spirduso & Clifford, 1978; Clarkson, 1978), who found that elderly people exhibiting an active life style react and move significantly faster than non-active people. A pos- sible explanation for the lack of a significant activity effect might be the failure to include truly sedentary males in this investigation. The lack of extreme activity groups may have failed to provide the range of differences in activity life style necessary to detect dif- ferences in performance. It is also possible that the activities engaged in by a majority of the active subjects, i.e., jogging and swinming, do not require fast reactions and therefore the reaction time performance of these active subjects would not be significantly different from those of their less active peers. Even so, the acti- vity main effect approached significance (P less than .078) in the current investigation, thereby lending some support to this interpre- tation. 98 Fractionated Reaction Time Age-related lengthening of reaction time due to a change in the quality of central nervous system processing rather than in the speed of muscular contraction has been reported previously (Birren & Botwinick, 1955; Weiss, 1965, Kroll & Clarkson, 1977; Clarkson, 1978). The results obtained in the present investigation are in general agreement with the findings of these earlier studies. A significant difference was found between the three age groups in premotor times. Young males, middle age males, and older males were significantly different from each other in the premotor time components of hand choice, f00t simple and feat choice reac- tion time when the four premotor time variables were analyzed alone. However, when the sixteen variable MANOVA was applied, the three groups were not significantly different from each other in the premotor time component of foot simple reaction time. In both the four and sixteen variable analyses, the young males were signi- ficantly different from the older males in premotor times associated with hand choice and foot choice reaction time but were not in pre— motor times associated with hand simple and foot simple reaction time. Middle age males were not significantly different from older males on any of the premotor time variables. The results of this investigation revealed that the three age groups were significantly different from each other only in motor time associated with feat choice reaction time in both the four variable and the sixteen variable MANOVA analyses. Young males, middle age males and older males were not significantly different 99 from each other on the rest of the motor time variables. This part of the results partially agrees with the findings of Botwinick and Thompson (1966), who faund that elderly subjects are slower than young subjects in both premotor time and motor time components. The results of the fractionated reaction time analyses also showed that active males were not significantly different from less active males on either the premotor or the motor time components in both the four variable MANOVAIand the sixteen variable MANOVA.pro- cedures. These results are in contradiction with the findings of Clarkson (1978). Again, the lack of a difference may be explained by the failure to include sedentary males in the research design or by the type of activity engaged in by the active subjects. CHAPTER V SUMMARY, CONCLUSION, AND RECOMMENDATIONS Summary The purpose of this investigation was to compare the frac- tionated reaction time and movement time performances of male sub- jects across various age and physical activity levels. More spe- cifically, this study was designed to compare the fractionated simple reaction time of the hand and foot, the fractionated choice reaction time of the hand and foot, as well as movement time of the hand and foot for 120 male volunteers from the University comnunity at Michigan State. The subjects were divided into six groups accord- ing to age and level of physical activity. TWO groups included men 20 to 30 years of age, two middle age groups were comprised of men ranging in age from 40 to 51 years and two older age groups were made up of men between 58 and 79 years of age. Three practice trials were given to permit the subjects to become familiar with the equip- ment and procedures. Following the practice trials, each subject completed a total of 48 trials including 12 hand simple, 12 hand choice, 12 foot simple, and 12 foot choice reaction time trials. The data were analyzed by multivariate analysis of variance procedures to detect any significant difference in the performance of the three age groups or the two activity groups on total reaction time, premotor time, motor time, and movement time. Analysis of the 100 101 data indicated that age generally was a significant factor in total reaction time (i.e., hand simple, hand choice, foot simple and foot choice reaction time), in premotor time, in motor time associated with foot choice reaction time and in movement time performance. Young males were significantly faster than older males in hand choice reaction time and foot choice reaction time, but not different in hand or foot simple reaction time. Middle age males also were faster than older males in hand simple reaction time, hand choice reaction time, and foot choice reaction time, but not in foot simple reaction time. Young males were significantly faster than older males in the premotor times associated with hand choice reaction time and foot choice reaction time, but not in the premotor times associated with hand simple and foot simple reaction time. The two groups of middle age males and older males were not significantly different from each other on any of the premotor times. Young males were significantly faster than older males only in motor time associated with foot choice reaction time. Middle age males also were significantly faster than older males but only on motor time associated with foot choice reaction time. Young males were not significantly faster than older males in movement time. However, middle age males were significantly faster than older males in movement time performance associated with hand simple, hand choice and foot choice reaction time. Active males and less active males were not significantly dif- ferent from each other in terms of (a) total reaction time (i.e., hand 102 simple, hand choice, feat simple or foot choice reaction time); (b) premotor times; (c) motor times; or, (d) movement time. The same results were obtained when all sixteen reaction time variables were included in one analysis when they were analyzed in four sets of related variables. Conclusions The following conclusions are drawn from the results of this study within the limitations outlined in Chapter One: I. The premotor time component is longer than the motor time component of reaction time. Hand reaction time is faster than feat reaction time. Most of the difference between simple reaction time and choice reaction time performance is in the premotor time component of reaction time. Age is a significant factor in the (total) reaction time of the hand and foot. It influences performance on both simple and choice reaction time tasks. Age is a significant factor in premotor time assOciated with hand simple, hand choice, foot simple and foot choice reaction time. Age is a significant factor only in motor time associated with feat choice reaction time. Age is a significant factor in movement time associated with hand simple, hand choice, foot simple and foot choice reaction time. 10. 11. 12. 103 Activity is not a significant factor in the (total) reac- tion time of the hand and foot, including simple and choice reaction time tasks. Activity is not a significant factor for the premotor time component of hand simple, hand choice, feat simple and foot Choice reaction time. Activity is not a significant factor for the motor time component of hand simple, hand choice, foot simple and foot choice reaction time. Activity is not a significant factor in the movement time responses associated with hand simple, hand choice, foot simple and foot choice reaction time. No interaction effects occurred between age and activity for any of the dependent variables mentioned above. Recommendations The following suggestions are offered for future research on the problem investigated in this study: 1. The subjects in the present study were volunteers from the university community at Michigan State. It is recom- mended that a larger number of subjects in the various age groups be included who are selected on a random basis. Future studies sh0u1d include both male and female subjects. The effect of the length of the pre-stimulus interval and the nature of the pre-stimulus warning signal on frac- tionated reaction time and movement time should be examined. 104 Since categorizing the subjects into active and less active groups on the basis of self-reporting activity history of the subject has some serious limitations, replication of the study wjth active males whose activity history is determined from sources other than a self- reporting instrument is recomnended. Active subjects in this study engaged in different sports activities. It is recomnended that comparisons be nade between active individuals who participate in endurance activities and those who engage in activities that re- quire rapid decisions. Lack of interest and motivation resulted in sedentary individuals declining to participate in this study. More persistent efforts should be made in future in- vestigation to include such persons. For the purpose of discovering the residual effect of sports participation on fractionated reaction time and movement time performance, a clearly defined group of formerly active subjects should be included in future investigations. In this study, the electrodes were attached to the "hamstring" muscles far all the foot reaction time tasks. The possibility exists that electrodes should also be attached to other muscles for the foot choice reaction time and movement time tasks since the foot is required to be moved in any of three different directions (forward, 105 sideward or backward). It is recommended that in future studies the electrodes be attached to different muscles of thigh to determine if more than one source of input for these movements is necessary. Since the subjects were tested between 9:00 A.M. and 6:00 P.M., the time of testing should be used as covar- iate in future studies of reaction time where time of day may be a factor in performance. APPENDIX A APPENDIX A Dear Thank you far agreeing to participate in the reaction time and movement time study sponsored by the Department of Health, Physical Education and Recreation. Your cooperation is greatly appreciated. The following information is provided to help reduce your time in the laboratory. Dress - Please bring gym shorts or swimming trunks and rubber soled shoes far the testing. Shaving - To expedite the placement of surface electrode you are requested to shave the following body surfaces: 1. Upper posterior half of the forearm of the dominant hand (Figure I). 2. Middle part of the posterior thigh of the dominant leg (Figure II). 3. Chest over the sixth rib (Figure III) R? has: "fl!“ 106 107 Testing Procedures Hand Reaction Time. You will sit on a chair with the dominant hand over the releasing reaction time button. Adjust your position until you can comfortably touch each of the hand Microswitches. The signal lights will be located in frdnt of you. Place the index fin- ger of your dominant hand on the reaction time button. At the stim- ulus of light on choice reaction time task, move your hand and your arm in a forward direction with the greatest possible speed from the reaction time button to the appropriate Microswitch. For the simple reaction time test, move your hand to touch the middle Microswitch. Foot Reaction Time. You will stand in position wfith dominant foot on the reaction time button. Adjust your position so that you can comfbrtably touch each of the three foot Microswitches. The signal light will be located in front of you. Place your dominant foot on the reaction time button. At the stimulus of light on the choice reaction time test move your foot in a forward, sideward, or backward direction with the greatest possible speed from feat reaction time button to the appropriate fact switch. For the simple reaction time task you will move your foot in a forward direction to touch the Microswitch. For both the hand reaction time and foot reaction time tasks, a warning signal (buzzer) will be given to you prior to each trial. The time between the warning signal and the stimulus will be randomly 108 varied from half of a second to three seconds. Three practice trials wjll be given to permit you to become familiar with the equipment and procedures. Following the practice period, you will be given 12 con- secutive trials on each of the four tests. The order far hand reac- tion time and feat reaction time testing will be randomly detenmined. The twelve trials far choice reaction time will follow the twelve simple reaction time trials. Thus a total of 48 trials will be taken (simple reaction time - hand and foot; and, choice reaction time - hand and foot). The estimated time required for each subject to be tested is 1 to 1% hours. You also will be asked to complete a brief biographical form so that appropriate demographical infonmation and your activity history can be obtained far analysis of the data. Your appointment for testing is on (day) , (date) AM PM. (time) If this appointment is not convenient for you, please call far a reappointment. APPENDIX B APPENDIX B MICHIGAN STATE UNIVERSITY Department of Health, Physical Education and Recreation Reaction Time Study Subject History NAME SUBJECT NUMBER (last) (first) TODAY'S DATE BIRTHDATE (month) (day) (year) (month) (day) (year) AGE OCCUPATION (year) (month) What are the physical demands of your occupation? (Hours of standing, walking, physical labor, etc.) Circle the age group appropriate for you: 20-30 40-50 60 and older Identify the activity group that best describes you and complete the infonnation requested. Active Group: Men who have been physically active most of their lives and who currently run or swim thirty (30) minutes or more at least 3 times per week. 1. For how many years have you been involved in this swimming and/or running program? years Briefly describe your weekly activity schedule. 2. In addition to the above, have you engaged in a regular physical activity program during the past 5 years? yes no 109 110 3. If yes, briefly explain the nature, extent (intensity) and duration of participation in this program. 4. In the space below indicate your involvement in organized physical activity programs up until about five years ago. Include your involvement in high school and college sports programs. Formerly Active Group: Men who were physically active during their younger years, but have not been involved in vigorous physical acti- vity programs for at least 5 years (20-30 age roup), 10 years (40-50 age group) or 20 years (60 and older age group?. 5. Far how many years were you actively involved in vigorous physical activity? years 6. In the space below, please describe the nature, extent (intensity) and duration of participation in such activity. Non-active Group: Men who do not exercise regularly and who never partiCipated in organized physical activities on a regular basis. 7. Did you ever participate in an organized program of physical activity (other than required physical education classes in school) that was one or more years in duration? yes no (If yes, you should be completing one of the previous sections). 111 8. Briefly describe the nature, duration and extent (inten- sity) of your involvement, if any, in organized physical activity prograns that was less than one year in duration. 9. Have you regularly engaged in physical activity on a recre- ational (free play) basis during your lifetime? yes no 10. If yes, briefly describe the nature, duration and extent (intensity) of such participation. THANK YOU FOR YOUR COOPERATION! APPENDIX C APPENDIX C REACTION TIME CONTROL UNIT *5 sum ’7” +.r __ ° 5" _.I_. +5 Buzzsg +5 IR scoPE WW INPuT NOTE: A (.4 Sourcing — NORMAN-Y OPE” 4: amp Swrrcllg - I I . . I -—-I REACTION ——-> a > , . I F‘— I ——— ' I—I | 1_> 1 I—) 4 ‘fi vV ‘ v I ISWMULUS' ""'""""‘ I I RESPONSE , I_ _ _ QEC-Hflr’flfiL_C0:Ul:Tl_0-N _ _ _ _ ® 5217' Sun c +5 #3” I Q'— I I Ik .00! M Maurice! 1 >.._— g ' L 20”; . fl {-7412 . I (OK our t to I _; )___. H‘ . , I 3. © “um I melt __ 3 c . _ 3' '_7 I >___' _ T ail/292‘ I 1" ”my, I Who 112 113 ’66.! Wok I “ ' ' ‘ l’. . ISOLATION 10k +6”: 7M °— mum" J7 ,0 o— macay ..._..I 0" . DEWcts CSCOSS‘ OI 2247' 1 _ 37k a” L .. ,- -‘.3 . ENG 2- Ettenoogs “'1 ' In no @o-I Powsg 1'- ;(‘AMP .9317! "1 ’— ioecon T fi‘ % N. l vac °" 7‘ :— ®“’"‘I l,@_II 7 TM? ' °"'" ' E Star I I l Srinutug- | +5 RB ”NuH 3"@— 3 ‘0 Ha. ‘ 105051 '@ I I mszeoI - 5+5 * fi' 2500 .L 10 I Isv I Isv W505; . mm ' I - 7 Mn]! L ‘+6 2 I I he I "" F-st : - 5.3V .GA III/5051 1" . I: L _ 21111905 _ 6 .1 BIBLIOGRAPHY Bibliography Abrahams, J.P. and Birren, J.E. Reaction Time as a Function of Age and Behavioral Predisposition to Coronary Heart Disease. J. of Gerontology, 1973, Vol. 28, pp. 471-478. Beagley, H.A. and Sheldrark, 0.8. Differences n Brainstem Response Latency with Age and Sex. British J. of Audiology, 1978, Vol. 12, pp. 69-77. Bellis, C.J. Reaction Time and Chronological Age. Proceedings of the Society for Experimental Biology and Medicine, 1933, Vol. 36, pp. 801-803. Birren, J.E. and Botwinick, J. Speed of Response as a Function of Perceptual Difficulty and Age. J. of Gerontology, 1955, Vol. 10, pp. 433-436. Birren, J.E. and Spieth, W. Age, Response Speed and Cardiovascular Functions. J. of Gerontology, 1962, Vol. 17, pp. 390-391. Birren, J.E. Translations in Gerontology--From Lab to Life: Psycho- physiology and Speed of Response. Am. Psychologist, 1974, Vol. 29. PP. 808-815. Botwinick, J. 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