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'_————"' _____—— — ’__.——- f——— ___._——-—— # m, ___._—-— 3212931 LIBRARY Michigan State University This is to certify that the thesis entitled SIMPLE REACTION TIME, CHOICE REACTION TIME, . AND ARM MOVEMENT TIME IN NORMAL CHILDREN AND IN THOSE WHO ARE MOTORICALLY HANDICAPPED presented by Ardavan E-Lotfalian has been accepted towards fulfillment of the requirements for Master of Arts degree in Physical Education /£ {WM Major prosfe or Date July 25, 1978 0-7639 SIMPLE REACTION TIME, CHOICE REACTION TIME, AND ARM MOVEMENT TIME IN NORMAL CHILDREN AND IN THOSE WHO ARE MOTORICALLY HANDICAPPED BY Ardavan E-Lotfalian A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF ARTS Department of Health, Physical Education and Recreation 1978 CD ABSTRACT SIMPLE REACTION TIME, CHOICE REACTION TIME, AND ARM MOVEMENT TIME IN NORMAL CHILDREN AND IN THOSE WHO ARE MOTORICALLY HANDICAPPED BY Ardavan E-Lotfalian The purpose of the study was to compare the simple reaction time, choice reaction time and arm movement time of normal children with those who were motorically handi- capped. The subjects were two groups of male children, 32 in each group, ranging in age from 6 to 9 years who were randomly selected from those attending the Motor Perform- ance Study or the Remedial Motor Clinic at Michigan State University. The apparatus for assessing reaction time and move- ment time consisted of a stimulus unit, a response unit, and recording unit. The stimulus unit contained three colored lights and a buzzer. The recording unit consisted of two chronoscopes accurate to the nearest 1/100 second. The response unit included one releasing reaction button and three microswitches placed 25 centimeters apart. At the stimulus of a light or sound the subject moved the hand and arm in a forward direction from the releasing button to the appropriate microswitch. Following a brief practice Ardavan E-Lotfalian period, the subject completed 15 trials for each of the three dependent measures. Two way analysis of variance was used to analyze the data. The following conclusions were drawn from the re- sults obtained: 1) the simple visual reaction time and the choice visual reaction time of the normal boys was sig- nificantly faster than that of the motorically handicapped boys; 2) the simple auditory reaction time scores of motor— ically impaired boys was not significantly different from that of the normal boys; 3) the performance of the normal males was superior to that of the motorically impaired males for movement time performance associated with each of the reaction time measures; and 4) the pattern of re- sponses of the normal boys across trials for simple reac- tion time, choice reaction time and movement time generally did not differ from that of the motorically handicapped boys. TO MY WI FE ii ACKNOWLEDGMENTS I sincerely wish to thank my committee chairman and academic advisor, Dr. John Haubenstricker, for his invaluable assistance in the planning and preparation of this thesis. I am deeply indebted for the tremendous amount of time he devoted to all phases of this research. His generosity and patient indulgence were greatly appre- ciated. I would also like to gratefully acknowledge the contributions of the other members of my committee, Dr. Vern Seefeldt and Dr. Wayne Van Hass. They offered many suggestions and constructive criticisms to improve the quality of this study. Special thanks and sincere appreciation are expressed to Dr. William Heusner for his guidance in the statistical analyses of the data. I would also like to thank Bob Wells for his helpful assistance in the con- struction of the apparatus; and, Molly Sapp for her assistance in collecting the data. Finally, appreciation is expressed to the children who willingly participated as subjects in this study. iii TABLE OF CONTENTS LIST OF TABLES . . . . . . . . . . . . . . . . . . LIST OF FIGURES O O O O O O O C O C C C O O O O 0 Chapter I. INTRODUCTION . . . . . . . . . . . . . . Statement of the Problem. . . . . . Hypotheses. . . . . . . . . . . . . Need for the Study. . . . . . . . . Research Plan . . . . . . . . . . . Limitation of the Study . . . . . . Definition of Terms . . . . . . . . II. REVIEW OF LITERATURE . . . . . . . . . . Age and Sex Differences in Reaction time and movement time. . . . . Reaction Time in Normal and Special Populations . . . . . . . . . . Sensory Modality and Reaction Time. Simple and Choice Reaction Time . . smary O O O O O O O O O O O O O 0 III. EXPERIMENTAL METHOD . . . . . . . . . . Subjects. . . . . . . . . . . . . . Testing Environment . . . . . . . . The Apparatus . . . . . . . . . . . Testing Procedure . . . . . . . . . iv Page vi viii ll 17 21 25 27 27 27 28 29 Chapter Determination of Dominant Hand . . . Statistical Design . . . . . . . . . 'Iv. RESULTS AND DISCUSSION . . . . . . . . . Results . . . . . . . . . . . . . . Descriptive Statistics. . . . . Inferential Statistics. . . . . Discussion . . . . . . . . . . . . Reaction Time . . . . . . . . Movement Time . . . . . . . . . V. SUMMARY, CONCLUSIONS AND RECOMMENDATIONS. Summary . . . . . . . . . . . . . . Conclusions . . . . . . . . . . . . Recommendations . . . . . . . . . . BIBLIOGMPHY O O O O O O O O O O O O O O O O O 0 APPENDIX 0 O O O O O O O C O O O O C O O O O O O Page 30 31 32 32 33 36 43 48 50 52 52 54 55 56 61 LIST OF TABLES Means and standard deviations for the reaction time scores of boys enrolled in the Motor Per- formance Study (MP5) and the Remedial Motor Clinic (RMC) at Michigan State University . . Means and standard deviations for the movement time scores of normal boys enrolled in the Motor Performance Study (MP8) and the Remedial Motor Clinic (RMC) at Michigan State Univer- Sity o o o o o o o o o o o o o o o o o o o ' Two-way analysis of variance results for simple visual reaction time . . . . . . . . . Two-way analysis of variance results for movement time associated with simple visual reaction time . . . . . . . . . . . . . . . . Two-way analysis of variance results for Simple auditory reaction time . . . . . . . . Two-way analysis of variance results for movement time associated with simple auditory reaction time . . . . . . . . . . . . . . . . Two-way analysis of variance results for choice reaction time . . . . . . . . . . . . Two-way analysis of variance results for movement time associated with choice reaction time . . . . . . . . . . . . . . . . Repeated measures analysis (AOV) of the pattern of responses across trials . . . . . Repeated measures for analyzing the pattern of responses of 6-7 year old males in the Remedial Motor Clinic on Simple visual reaction time . . . . . . . . . . . . . . . . Repeated measures for analyzing the pattern of responses of 8-9 year old males in the Motor Performance Study on movement time associated with simple reaction time . . . . . . . . . . vi Page 34 35 37 37 38 39 4O 41 44 61 61 Repeated measures for analyzing the pattern of responses of 8-9 year old males in the Remedial Motor Clinic on movement time associated with Simple visual reaction time Repeated measures for analyzing the pattern of responses of 6-7 year old males in the Remedial Motor Clinic on choice reaction time 0 O O I O O O I O O O O O I O O O O O 0 Repeated measures for analyzing the pattern of responses of 6-7 year old males in the Remedial Motor Clinic on movement time associated with choice reaction time . . . Repeated measures for analyzing the pattern of responses of 6-7 year old males in the Motor Performance Study on movement time associated with choice reaction time . . . vii Page 62 62 63 63 4.4 4.6 LIST OF FIGURES Page The apparatus . . . . . . . . . . . . . . . . . 28 Mean performance for blocks on simple visual reaction time of normal boys and motor- impaired boys 0 O O O O O O O O O O O O O O O C 42 Mean performance for blocks on movement time associated with Simple visual reaction time of normal boys and motor-impaired boys. . . . . 42 Mean performance for blocks on Simple auditory reaction time of normal boys and motor- impaired boys . . . . . . . . . . . . . . . . . 45 Mean performance for blocks on movement time associated with simple auditory reaction time of normal boys and motor-impaired boys . . . . 45 Mean performance for blocks on choice reaction time of normal boys and motor-impaired boys . . 45 Mean performance for blocks on movement time associated with choice reaction time of normal boys and motor-impaired boys . . . . . . 46 viii CHAPTER I INTRODUCTION Reaction time, the interval of time between the pre— sentation of a stimulus and a muscular response, is of funda- mental importance in human behavior. The ability to react to stimuli is necessary in motor activities such as driving a car, playing volleyball or football, and at the beginning of most athletic contests. Thus, reaction time is a basic element in most tasks. However, in some tasks its importance is more critical than in others. In addition, athletic coaches have traditionally assumed that reaction time is a component that distinguishes between outstanding, average and poor performers in many sport skills. For this reason, it is not surprising that experimental psychologists and educators interested in human motor performance have con- ducted a considerable amount of research in the Speed of reaction and the factors that influence it. Statement of the Problem This study was designed to compare the simple reac- tion time, choice reaction time, and arm movement time of normal children enrolled in the Motor Performance Study with motor-handicapped children attending the Remedial Motor Clinic at Michigan State University. Hypotheses Three hypotheses were tested in this investigation: 1. The Simple reaction time and movement time performance scores of motor-handicapped children do not differ from those of motorically normal children. 2. Normal children have faster choice reaction time and movement time than motor-handicapped children. 3. The pattern of responses of normal children across trials for simple and choice reaction time differs from the pattern of responses of motor handicapped-children. Need for the Study In recent years, many studies have been devoted to the subject of reaction time and speed of movement in handicapped populations. However, these studies have been directed mostly toward mentally retarded adolescents and adults. Retardation is typically conceptualized in terms of level of performance on some normative scale. Thus, retarded individuals are usually described as being "slower" or fpoorer" than normal individuals. This, however, is not an adequate description of the behavior of retarded individuals. Baumeister and Kellas (1968) suggest that the behavior of mentally retarded individuals~ is, in some instances, characterized as much by a lack of consistency as by a low level of responding. Basically, this study is concerned with a comparison of the reaction time and movement time of normal and motor- handicapped children in an attempt to discover whether reaction time or movement time performance differs among these groups of children. Also, the lack of information about the reaction time and movement responses of the motor-handicapped children requires basic or descriptive research in order to provide a scientific base for many of our present concepts and assumptions. Research Plan The subjects were two groups of male children, 32 in each group, ranging in age from 6 to 9 years, that were randomly selected from the children attending the Motor Performance Study or the Remedial Motor Clinic at Michigan State University. The apparatus consisted of a stimulus unit, a response unit, and a recording unit. The stimulus unit was composed of three colored lights (red, green, blue) and a buzzer. These were used as the visual and auditory stimuli, respectively. The recording unit consisted of two 110 A.C. 1/100 second chronoscopes. The response unit included one releasing reaction button and three microswitches placed 25 centimeters apart. At the stimulus of light or sound (buzzer) the subject moved the hand and arm in a forward direction with the greatest pos- sible Speed from the releasing button to the appropriate microswitch. Following the practice period, the subject completed 15 consecutive trials. Two-way analysis of variance was used to analyze the data that were collected by the above procedure. Limitation of the Study The study was subject to two limitations. The dominant upper limb was used for testing both Simple and choice reaction time. Another limiting factor in this study was the lack of knowledge concerning the motivational factors which influenced the performance of the children. 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 requiredtx>move the domi— nant hand 25 centimeters in a forward direction. Simple Reaction Time. The time required for a sub- ject to react to.a specified stimulus with a prescribed response. Choice Reaction Time. The time required for a subject to react to stimuli presented randomly with pre- scribed corresponding responses. Dominant Hand. The hand that is consistently pre- ferred in any given activity. CHAPTER II REVIEW OF LITERATURE The purpose of this study was to compare the Simple reaction time, choice reaction time, and arm movement time of normal children enrolled in the Motor Performance Study with motor—handicapped children attending the Remedial Motor Clinic at Michigan State University. The review of litera- ture related to this study is divided into four categories: 1. Age and sex differences in reaction time and movement time; 2. Reaction time in normal and special populations; 3. Sensory modality and reaction time; and 4. Simple and choice reaction time. Age and Sex Differences in Reaction Time and Movement Time Determination of the relationship between reaction time, movement time and chronological age has been the sub- ject of numerous investigations (Bellis, 1933; Pierson, 1957; Mendryk, 1960; Hodgkins, 1962). The results of most studies have demonstrated a significant relationship between reaction time performance and chronological age. However, this rela- tionship is not linear in nature. Significant relationships between chronological age and movement time scores also have been obtained. Bellis (1933) studied the reaction time of 150 males and females sampled at random and ranging in age from four to sixty years. He obtained the shortest reaction time scores from subjects between the ages of twenty-one and thirty years, with a decrease in performance from the younger and older age groups. In another study, the reaction time and movement time of 400 male subjects between the age of eight and eighty-three years were assessed (Pierson, 1957). He found that both movement time and reaction time were Sig- nificantly related to chronological age. The fastest move? ment and reaction times occurred at 19 and 20 years of age. However, the greatest stability of individual movement time and reaction time performances was recorded from 26 through 30 years of age. The curvilinear relationship between chronological age and reaction time-movement time performances applies to both males and females. Junior high school age boys, and middle age men were 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 twelve, twenty-two and forty-eight years of age, respectively. Mea- sures were taken of reaction time and movement speed for a short arm-thrust as well as for a longer arm movement involv- ing a circular component. Fifty trials were completed by each subject with the Short movement, followed by sixty trials with the long movement. Only the last 30 trials of ‘each movement were analyzed. The 12 year-old subjects were 15 percent slower than the 22 year-old males in both the 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 per- cent difference involving the long movement. There were no Significant differences between the performances of the 12 year old and 48 year old subjects in any of the measures. Hodgkins (1962) examined the relationship of reaction time to movement time in 480 girls and women ranging from Six to eighty-four years of age. In addition, the influencecfifage on speed of reaction and speed of movement was investigated. Results of the study showed that reaction time and movement time were uncorrelated at all age levels studied, except be- tween the ages of 22 and 37 years. The author concluded that reaction time improved with age up to age 19, remained constant to age 26, and then accelerated with age. Movement time improved with age up to 15, remained constant to age 19, and deteriorated thereafter. The changes in reaction time associated with increas- ing age are not due to the length of peripheral pathways, but rather are a function of central nervous system processes. Birren and Botwinick (1955) compared thepxmformance of thirty- two young subjects between the ages of 18 and 36 years, and thirty-two elderly subjects between the ages of sixty and ninety-one years in simple auditory reaction time for the finger, jaw, and foot. The purpose of the study was to de- termine if the elderly subjects showed a disproportionate slowing of foot responses compared with those of the finger and jaw. The hypothesis was that the Slowing of reaction time with advancing age is correlated with the pathway length of the peripheral nerves. They reported that the reaction times of the elderly subjects were significantly slower than those of the younger subjects. They also concluded that the age change in reaction time is not associated with the length of the peripheral pathway. Similar results were reported by Weiss (1965). Weiss, in a simple auditory reaction experi- ment, used irregularly ordered preparatory intervals of l, 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 age groups rang- ing in age from eighteen to thirty and from sixty-five to eighty years, respectively. He indicated that changes in reaction time, because of set of motivation, occurred pre- dominantly in the premotor component and were therefore seen primarily as central rather than peripheral phenomena. He also concluded that the predominant differences in reaction time between the two age groups was in the premotor component. Computation of comparative conduction times in the peripheral nervous system suggested that the differences obtained were largely accounted for by central nervous system functions. There is evidence that older subjects exhibit Slower response speeds across many tasks, whereas young adult sub- jects are more task-specific in their response speed. In an attempt to determine age differences in response speed as a function of controlled variationcnfstimulus conditions, Birren, Riegel and Morrison (1962) tested 30 young subjects, ranging in age from eighteen to thirty years and twenty- three elderly subjects ranging in age from sixty to eighty years. A total of 22 stimulus-response conditions were studied. Each series of conditions was presented twice. The largest age differences in response speed, both relative and absolute, appeared for the superordinate, co-ordinate, and part word relationships, and for the color and color symbol associations. The smallest differences between the two age groups were found for choice reaction time and adjec- tive word relationships. It was apparent that age differ- ences in speed of response were not limited to the simple motor aspects of the tasks but also included verbal processes. The slowing in reaction time with advancing age is not a function of stimulus intensity. Botwinick (1972) com- pared 12 younger women subjects ranging from eighteen to twenty-one years, and twelve elderly subjects ranging from fifty-four to seventy-one years. The comparison was made to determine whether the slowing reaction time,typica11y seen in later life, would be negated by functionally equating the intensity of stimulation. Two intensities of stimulation were used with each subject; 10 and 30 decibelsabove the 100 percent threshold decibel level. The performances of the 10 elderly subjects were Significantly Slower than those of the younger subjects. Both age groups reacted faster to the stronger stimulus than to the weaker one. Botwinick indicated that input or sensory factors did not seem important, suggesting that central mechanisms may under- lie the Slow-down in performance among the elderly. The reaction time and movement time of individuals on specific tasks are generally not Significantly related (Mendryk, 1960; Hodgkins, 1962). Groves (1973) investigated the independence of reaction time and movement time in the gross motor skill (the racing start in swimming) of 16 members of the University of Missouri swimming team. The mean age of the group was 20 years with an average of eight seasons of competitive swimming experience. He quantified reaction time and movement time for each subject by counting frames of film for five trials. A Pearson-product-moment coefficient of -.231 (P:>.05) obtained between the mean reaction time and movement time performances of the subjects indicated that these two factors were independent. In a study conducted by Magill and Rowell (1975) it was hypothesized that the reac- tion time-movement time correlation coefficient Should not be subject to variation due to the manipulation of various experimental variables. They tested 18 males and 18 females iranging in age from 19 to 24 years. The reaction time and movement time performance of the 18 males and 18 females were secured during the same test session and also during a separate testing session. Of primary interest in this 11 study was the relationship between reaction time and move- ment time for both conditions. The correlation between movement time and reaction time when measures for each were obtained during the same test session was .482 for men and .379 for women. When measures for reaction time and move- ment time were secured during separate test sessions.the values were .544 and .341 for the males and females, respec- tively. The correlations for the males were significantly different from zero (Pj>.05), while they were not signifi- cantly different from zero for the females. Males generally have demonstrated faster reaction times than females. Bellis (1933) indicated that males responded more quickly than females, especially in child- hood and late maturity. Philip (1935) found that there was a statistical difference between the reaction time scores of girls and boys. The boys reacted from 3 to 5 percent faster than girls, Goodenough (1935). Hodgkins (1962) and Marther (1964) also found that the performance of males was superior to that of females on reaction time tasks. Reaction Time in Normal and Special Populations Mentally impaired subjects are both Slower and more variable than normal subjects in their performance on mea- sures of reaction time. This is true for both simple and choice reaction time tasks across the various sensory modali- ties. Berkson and Baumeister (1967) compared reaction time of thirty normal and thirty institutionalized subjects by 12 having them respond to tones of different intensity. A tone stimulus was presented at 25, 50, and 75 decibels. The subjects were asked to release a telegraph key as soon as the tone sounded. The investigators reported that, in addition to being slower than normal individuals in reac- tion time tasks, the performance of mentally deficient subjects was more variable both between and within the sub- jects. Bonsett, Ross, and Kelly (1969) measured visual reaction time of six normal and six mentally handicapped children ranging in age from ten to thirteen years. Each subject received 5 practice trials and 20 test trials. All 20 trial values were used to calculate mean reaction time and variance measures for each subject. The mentally handi- capped children responded with slower and more variable reaction time performances than did the normal individuals. Kellas (1969) also compared the reaction time and response variability of normal and retarded individuals. He selected thirty-six male patients from a residential institution for the retarded, and an equal number of normal subjects from a population of undergraduate students. All subjects were given 54 trials, in three blocks of 18 trials on a simple auditory reaction time task. For both ability groups, reac- tion time variability was functionally related to the direc- tion of the reaction time response (key press and key release), preparatory intervals (2, 7.5 and 15 seconds), and reaction- signal intensity (30, 60 and 90 decibels). He found that both between and within-subjects variability was greater for 13 retardates than for normal subjects. In addition,within- subject variability was found to contribute more to the average performance of retardates than to normal subjects. Cafrey, Jones, and Hinkle (1971) conducted a study to explore the reaction time of 10 normal and 10 mentally retarded stu- dents (IQ 45 to 75) ranging in age from six years, two months to eight years, two months. The Lafayette Visual Choice Reaction-time instrument was used to measure the reaction time. A Wilcoxon matched-pairs Signed-ranks test Showed significant differences between the performances of the nor- mal subjects and the retarded individuals on both simple and choice tasks in favor of the normal subjects. High intra-individual variability may be as important a characteristic of reaction time performance in retardates as is their slowness in responding to stimuli. Baumeister and Kellas (1972) compared the performance of normal indivi- duals who had a mean chronological age of 25.7 years to Six mental retardates with an average chronological age of 21.4 years on a simple serial reaction time task. Several hundred responses were obtained from each subject. The distribution of responses for the retardates tended to be more variable, platykurtic and symmetric than those of the normal subjects. The latter showed typical leptokurtic distributions that were skewed to the right. It was suggested that retarded behavior is, in some contexts, characterized as much by a lack of consistency in performance as by a low level of re- sponding. 14 Reaction time scores tend to be greater in groups of subjects with low intelligence than in groups of subjects with normal intelligence when matched on the basis of chrono- logical age but this difference disappears when they are grouped according to mental age. Jones and Benton (1968) measured simple reaction time to both auditory and visual stimuli for normal and retarded children. The same subjects then were tested on a choice auditory reaction time task and a choice visual reaction time task. The results for the groups of subjects matched for chronological age Showed that the normal subjects responded more quickly than the retar— dates under all conditions. However, when the results of groups, differing in chronological age but matched for men- tal age, were compared, there were no significant differences between the normal subjects and those who were retarded. Grodon (1969) tested 54 mentally retarded children, with chronological ages ranging from 5 to 13 years (M = 8.66, SD = 2.30) and mental ages ranging from 3 to 13 (M = 7.33, SD = 2.05), to measure reaction time for relatively simple motor abilities and for complex perCeptual-motor ability. Reaction time was measured by means of a standard Lafayette visual reaction time apparatus. The median reaction time over 20 trials was determined. The two tests of Simple motor abilities involved specific muscular strength and finger oscillation. Complex perceptual-motor coordination was measured by a device referred to as a key press. Mean and standard deviations for the measures were as follows: 15 visual reaction time = .59 sec. and .08 sec.; motor strength = 12.26 and 2.48 sec.; finger oscillation = 31.67 and 6.48 sec.; key press = 14.54 and 4.71 sec. Performance on all of these tests were found to be significantly and highly related to mental age. It was also determined that when holding motor strength, finger oscillation and chronological age constant, the significant relationship between reaction time and men- tal age still persisted. In contrast to results obtained with normal subjects, the reaction time of learning disabled subjects does not appear to be influenced by the duration of the interval pre- ceding stimulus onset. Czudner and Rourke (1970) employed two different reaction conditions to explore differences in the "mental set" between one group of children with electro- cephalographic evidence of cerebral dysfunction (the "brain damaged" group) and a control group of normal children. There were 15 boys in each group matched for age and IQ. The procedure consisted of regular and irregular preparatory interval conditions. Czudner and Rourke demonstrated that latency in response was directly related to the length of the preparatory interval for normal, but not for brain- damaged, subjects. In addition, the normal control subjects performed significantly (P<(.01) better on a constant pre- paratory interval than on an irregular preparatory procedure. Gosling and Jeness (1974) also found that: (a) reaction times were Shortest when the preliminary interval was equal to or greater than the previous preliminary interval, (b) l6 reaction times were impaired when the preliminary interval was less than the previous preliminary interval, and (c) that the degree of impairment was directly related to the differences between two fore-period values. All of these effects were significantly greater for the retarded than for non-retarded subjects. Finally, an increase in the interval had little effect on non-retarded subjects, but tended to accentuate the results in the retarded subjects. Both non-retarded and retarded subjects exhibit a psychological refractory period when preparatory periods are irregular in nature. Fredrich, Libkuman, and Hawkins (1974) tested 12 non-retarded and 12 retarded subjects, to compare the response-stimulus interval performance of nor- mal and retarded subjects under regular and irregular con- ditions. Mean ages for non-retarded and retarded groups were 35.83 (SD = 15.22) and 40.33 (SD = 11.11), respectively. Mean 10's for the retarded groups receiving the regular and irregular procedures were 54.33 (SD = 12.33) and 60.17 (SD = 5.27), respectively. The investigators found a sim- ilarity between the dual reaction time performance of non- retarded and retarded subjects. Both the non-retarded and retarded subjects showed a psychological refractory period only after the 250-millisecond response-stimulus interval under the irregular procedure. Performance under all other conditions indicated that, regardless of presentation proce- dure, the first stimulus (or the first stimulus and reaction to it) established an expectancy for the second stimulus. It 17 was concluded that this expectancy results in faster reac— tion time to the second stimulus than to the first. Mental age,rather than IQ, is important for infor- mation processing in reaction time tasks. Marelan (1976) tested 20 non—retarded children (IQ 90 to 115) and 20 re- tarded children (IQ 55 to 79) to investigate the relative effects of mental age and IQ on processing information. After 40 practice trials, each subject was given 3 blocks of 100 trials, with a 2-minute rest period imposed after every 50 trials. The results of the analysis of variance indicated no main effect attributable to intelligence, but a significant main effect of mental age. Sensory Modality and Reaction Time Reaction time is related to the sensory modality through which a stimulus is presented. For example, the -reaction of an individual to an auditory stimulus is quicker than to a visual stimulus (Bellis, 1933; Goodenough, 1935; Dinnerston and Zlotogura, 1968; Breen, Haemer and Poock, 1969). Colgate (1968) compared the variation in reaction and response times of 50 male college students subjected to visual, auditory and tactile stimuli. Each subject responded eight times to each of the three sensory modes of stimulation. Mean reaction times and response times were computed for each subject on each type of stimulus. The group means were lower when subjects responded to the auditory stimulus than when they responded to visual or tactile (electric Shock) stimuli. In addition, both speed of reaction and speed of response were 18 faster when the subjects responded to visual stimuli in contrast to tactile stimuli. Related studies involving the variation of onset and termination of a stimulus indicate that auditory reac- tion time is faster than visual reaction time. The reaction time of 40 adult subjects to the onset and termination of lights and sounds was measured by Goldeston (1968). He found that auditory reaction time was faster than visual reaction time for both the onset and termination of stimuli. In addition, onset reaction time was faster than termination for both sensory modes. Sensory stimulation is related to the information pro- cessing demands of the motor responses that are to be made. The effect of auditory and visual stimulation on the informa- tion demands of discrete motor responses was studied by Breen, Haemer, and Poock (1969). They defined "information process- ing demands" an index of difficulty (ID) as ID = log2 ($5), where A is the movement amplitude between a starting button and a target and W is the target width. Six military offi- cers ranging from 28 to 31 years of age were the subjects for the study. Two identical targets were located at equal distances from a starting plate. The subjects held a light- weight metal stylus on the starting plate and then moved the stylus as rapidly as possible to the left target on presentation of a low—pitched tone (250 Hertz) or to the right target when presented with a high-pitched tone (2,000 Hertz). The tones were presented through earphones. Under 19 the visual stimulus condition, subjects observed two lights and moved the stylus in the direction indicated by the light stimulus in any given trial. The investigators reported that under the condition of auditory stimulation the corre- lation between movement time and the amount of information processed was .92. When visual stimuli were used, the corre- lation between movement time and the information processed was .97. They concluded, however, that the amount of infor- mation processed in response to either visual or auditory stimulation was not related to the reaction time performance of the subjects. In a similar study, Suci, Davidoff, and Surwillow (1960) measured the visual reaction-time of two groups of 12 males. The median age of the older group was 63.0 years, whereas the median age for the younger group was 18.5 years. Two hypotheses were tested. The first was that reaction time is a linear function of stimulus information in both old and young subjects. The second hypothesis was that dif- ferencesin reaction time increase as a function of increasing amounts of stimulus information. Analysis of variance indi- cated that the hypothesis of linearity of regression could not be rejected for either age group. The slopes of regres- sion were .302 and .179 for old and young subjects, respec- tively. The differences between the obtained slopes was evaluated by the "t" test and found to be significant with t = 4.40, df = 92, P4(.01. On the basis of this result the second hypothesis also was supported. Another result was that 20 the older subjects reached the learning criterion in fewer trials than the younger subjects. In some motor activities, responses to kinesthetic stimuli would seem preferable to response to visual stimuli. Jordan (1972) randomly assigned 36 subjects with amean age of 20.61 years to one of three treatment groups (visual, visual and proprioceptive, proprioceptive, i.e. blindfold) involving a motor task. All subjects received three differ- ent forces of the stimulus (blade deflection) in a random but balanced fashion. Following 10 training sessions, the blindfolded subjects had significantly faster reaction times than the members of the other two groups. Total response times (reaction time plus movement time) were also faster for this group. In young children, interpolated somatosensory stimu- lation is more effective in inhibiting responses to a visual signal than is visual interpolated stimulation in inhibiting responsiveness to a tactile signal. Kaufman, Birch and Zach (1973) explored the interrelationship of the visual and soma- tosensory systems through the use of two reaction time models in one hundred and fifty-two middle class, white children ranging in age from 3 to 9 years. The first model was de- signed to examine the effects upon reaction time of a 3-minute period of intervening stimulation with a sensory modality not used as the signal for responding. Thus a light stimulus was the intervening variable for a tactile reaction time task, and vice versa. In the second model, the effect of presentation 21 in one sensory system upon reaction time to a subsequent stimulus in the other sensory system was examined. The evidence deriving from both models indicated a clear develop- mental change in the ways in which stimulation in one sensory system affects reaction time to a signal presented in another system. The most general finding indicated a change from somatosensory to visual with increasing age. Simple and Choice Reaction Time There is ample evidence that reaction time increases when an individual is required to respond differentially to a set of alternative stimuli (Hick, 1952; Hyman, 1953; Leonard, 1959; Burns and Moskowitz, 1972; Norrie, 1974). Leonard (1959) conducted an experiment to observe the effect of varying the number of alternatives on choice reaction time performance. The results showed a difference between simple reaction and two-choice reaction time performance, but no systematic differences among 2, 4, or 8 choice reac- tion time responses. Burns and Moskowitz (1972) selected twenty subjects, 3 females and 17 males ranging in age from 16 to 49 years, to determine the relationship between reac- tion time and the number of choice alternatives in an over— learned task. Each subject was asked to name visually dis- played numerals. Choice conditions were varied by present- ing 6 different sets of stimuli containing either 1, 2, 4, 8, 16 or 32 stimulus alternatives. Reaction time scores were found to be a function of the number of stimulus alter- natives available. AS the number of stimulus alternatives 22 increased, the time required to read also increased. Norrie (1974) studied the effect of movement complexity on the simple reaction, choice reaction and movement times of two groups of 24 college age male volunteers enrolled in physi- cal education classes. One group performed a task using a simple 4 inch movement from the reaction button to the appropriate response button. The other group was required to execute a complex movement in which the hand first moved forward 12 inches to stop a button and then returned to the appropriate response button. Both groups performed 20 trials under conditions involving 1, 2 and 4 choices, respectively. For both the simple and the complex move- ment tasks, simple reaction time was significantly faster than the choice reaction times. However, as the number of choices increased, the effect of movement complexity on reaction time lessened. Performance on choice reaction time tasks may improve with practice. Mowbray and Rhoades (1959) studied the effects of practice on visual choice reaction time. The study was concerned with two different conditions - reaction times to two choices and to four choices. For these condi- tions, the index and second finger of each hand were used. For the two-choice condition, the two index fingers were used, while for the four-choice condition all four fingers were required. Initially, five tapes were made for each condition, each with a completely different sequential order. Their experiment involved 15 replications, or trials. 23 Each replication consisted of viewing a tape that required two-choice and four-choice responsesto be made. A total of 3,000 responses were made for each tape. Thus 45,000 scores were obtained during the course of the entire exper- iment. The two-choice and four-choice stimulus conditions were alternated throughout, and all stimulus sequences for the two conditions were preceded by a Short practice period. Unfortunately, the experiment involved only one 22-year old subject. The investigators concluded that practice posi- tively influenced choice reaction time scores. In addition, practice reduced the times for two-choice reactions at a faster rate than it did for the four-choice reactions. Simple reaction time to a stimulus can be lengthened if the reaction stimulus is preceded by an irrelevant stimu- lus in the same sensory modality. Rubenstein (1964) measured the reaction times of subjects as a function of the interval of time between an irrelevant stimulus, and a reaction stimu- lus for both visual and auditory stimuli. Reaction time was inversely related to the length of the interval when both stimuli were presented in the same sensory modality, but remained relatively constant for stimuli presented through different sensory modalities. Both the absolute change and the percentage change in reaction time were greatest when both stimuli were visual in nature. The changes in visual reaction resulting from the variation of interval lengths were independent of the luminances of both the irrelevant and the reaction stimuli. 24 Supraliminal stimulation results in faster reaction time than subliminal stimulation. Zenhausern, Pompo and Ciaiola (1974) examined simple and complex reaction time as a function of subliminal and supraliminal accessory stim- ulation. Simple and complex reaction time to auditory stimuli were tested under seven levels of accessory stimulation (white noise). Only the highest level of stimulation (70 decibel above threshold) lowered reaction time. The other levels had no effects. The time required to reset to the second of two dis- crete stimuli separated by an interval of 0.5 seconds or less tends to be longer than the time needed to respond to the first stimulus. Kroll (1961) randomly assigned 20 male university graduate students by pairs into two experimental groups. The subjects were former athletes ranging in age from 24 to 44 years with a median age of N)and mean age of 31 years. The interval of time between stimulus presenta- tion was manipulated within the range of 50 to 500 milli- seconds. The results of his investigation indicated in- creased delays in responding to the second stimulus when the interval of time between the first and second stimulus presentation was 0.5 seconds or less. Preparatory cues such as a preceding warning Signal reduce reaction time to a stimulus. Reaction time also is related to the length of the time interval between the warn- ing signal and the presentation of the stimulus. Alken and Lichtenstein (1964) studied the reaction time of subjects 25 to regularly recurring visual stimuli. The experiment was designed to provide answers to the following questions. With regularly recurring visual stimuli, (a) what is the relationship between fore-period length and mean reaction time to light at the asymptote of the reaction time practice curve, and (b) what are the differences, for various fore- period lengths, in the effects of practice on mean reaction time to light? The predicted answers to both questions (a) and (b) were confirmed. First, the relationship between interstimulus time interval and reaction time to regularly recurring visual stimuli was best depicted as an increasing function which reaches an asymptote, but at a different time interval for each subject. In addition, practice resulted in a greater decrease in reaction time for the l and 2 seconds interstimulus intervals, than for longer intervals; this effect was most pronounced after exposure to the given inter- stimulus intervals. Summary On the basis of the results of previous studies the following statements appear justified: l. The shortest reaction times are between the age 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 age of twenty-six and thirty years. 3. Males respond more quickly than females in reaction time tasks. 4. Mentally handicapped children demonstrate Slower and more variable reaction times performance than do normal individuals. 26 5. Reaction time to an auditory stimuli is faster than reaction time to a visual stimuli. 6. With increasing age, there is ashift from greater tactile to greater visual responsive— ness. 7. Improvement in reaction time for a simple move- ment occurs early in practice, while that for a complex movement requires a longer period of time. 8. Reaction time and movement time are independent factors. A review of the literature reveals that there is limited research concerning the reaction time and movement time performance of children with motor dysfunction. Since the reaction time of brain damaged children is not influ- enced by the duration of preparatory intervals (Czudner and Rourke, 1970), the possibility exists thattfluaperformance of children with motor impairment could vary from that of normal subjects when decisions have to be made involving choice response tasks. CHAPTER III EXPERIMENTAL METHOD This study was designed to compare simple reaction time, choice reaction time, and arm movement time of normal children with motor-handicapped children enrolled in special programs at Michigan State University. Subjects Two groups of male children ranging in age from 6 to 9 years were selected for this study. The first group in- cluded 32 motor-handicapped males randomly selected from the population of boys attending the Remedial Clinic at Michigan State University. The second group consisted of 32 normal males selected from the boys enrolled in the Motor Performance Study at Michigan State University. Each group was divided into two subgroups, ranging from 6 to 7 and from 8 to 9 years, respectively. The establishment of subgroups for each chronological age was not possible due to the limited number of motor-handicapped males available for study. Therefore adjacent age categories were combined to form the subgroups. Testipg Environment The testing was conducted in a quiet room under the same conditions for all subjects. The apparatus was placed 27 28 upon a wooden table. The subjects were seated at the table facing the apparatus. The Apparatus The apparatus consisted of a stimulus unit, a response unit, and a recording unit. A picture of the apparatus is presented in Figure 3.1. Figure 3.1 - The Apparatus The stimulus unit was composed of three colored lights (red, green, blue) and a buzzer. These were used as the visual and auditory stimuli, respectively. The recording unit consisted of two 110 volt A.C. 1/100 second chronoscopes. The reSponse unit included one ~releasing reaction button and three microswitches placed 25 centimeters apart. All distances between the releasing 29 button and the three microswitches were the same. The chronoscopes were connected to the releasing button, the microswitches, the stimulus lights and the buzzer by a series of relays. This arrangement permitted the activa- tion of a stimulus light, or the buzzer to Simultaneously start the reaction time chronoscope. Release of the button stopped the reaction chronoscope, thus providing a measure of speed of reaction, and at the same time activated the movement time chronoscope. The slightest contact with one of the microswitches stopped the movement chronoscope. Simple reaction time and movement time were measured by the presentation of a red light stimulus, or by the onset of a buzzer. Random presentation of the blue green, and red lights served as the stimuli for obtaining measure of choice reaction time and corresponding movement times. TestingiProcedure The subjects were seated on a chair placed directly in front of the response unit and were told to adjust their position until they could comfortably touch the micro- switches. The dominant arm was slightly flexed at the elbow to allow for completion of the prescribed movements. The signal lights were located in front of the subject. The subject was instructed to place the index finger of his dominant hand on the button. A warning click was given prior to each trial. The time between the warning and the stimulus was randomly varied between one and three seconds. At the stimulus of light or sound (buzzer) the subject moved 30 the hand and arm in a forward direction with the greatest possible speed from the releasing button to the appropriate microswitch. The procedure was described and explained to each subject. Three trials were given to permit the sub- ject to become familiar with the equipment and procedures. Following the practice period, the subject completed 15 con- secutive trials. In the simple reaction time and movement time tasks each subject performed 15 trials to the visual stimulus and 15 trials to the auditory stimulus with the order randomly determined. The fifteen trials for choice reaction time always followed the simple reaction time tasks. Two administrators were present at the testing; one for recording the scores, the other for operating the apparatus. Test administration took place during the summer and fall of 1977. A pilot study was conducted during spring term, 1977 to determine the adequacy of the procedures as well as the number of trials to be administered. Since no learn- ing effects were evident after a few practice trials and the interest of the children began to wane after 50 trials, it was determined to limit the number of trials for each stimulus condition to fifteen. Thus, a total of 45 trials including 15 Simple auditory, 15 simple visual and 15 choice visual reaction time trials were given to each subject. Determination of Dominant Hand The dominant hand was determined by asking the sub- ject to pick up a small ball (which had been placed at the 31 subject's midline on a table directly in front of him) and to throw it as quickly as possible. Five trials were per- mitted in this manner and the hand used was recorded. Statistical Design The means and standard deviations for each of the reaction time and movement time measures were calculated. The data were analyzed by two-way analysis of variance to detect any significant difference in the performance of normal boys and motor-handicapped boys on simple visual reaction time, simple auditory reaction time, choice reac- tion time, and movement time following Simple visual reac— tion time, simple auditory reaction time and choice reac- tion time. Graphs depicting performance patterns in blocks of three trials were constructed for each group on Simple visual reaction time, simple auditory reaction time, choice reaction time, and the movement times associated with each' of the three measures of reaction time. A repeated measures or treatment-by-subjects design was used to analyze the data contained in the graphs. CHAPTER IV RESULTS AND DISCUSSION This study was designed to compare the simple reaction time, choice reaction time, and arm movement time of normal children enrolled in the Motor Performance Study at Michigan State University with motor-handicapped child- ren attending the Remedial Motor Clinic at Michigan State University. This chapter will begin with a presentation of descriptive statistics involving the performance means and standard deviations of the children on specific reac- tion time and movement time variables. The results of two— way analysis of variance for Significant differences between treatment and age groups will be presented as they relate to each of the hypotheses. These will be followed by graphic representations of the pattern of responses for the groups of children on each of the variables. Finally, a discussion offering some rationale for the observed data will be presented. Results Two groups of male children ranging in age from 6 to 9 years were involved in the study. Each group of 32 Subjects was divided by age into two subgroups consisting of 6 to 7 32 33 year old and 8 and 9 year old boys, respectively. Each sub- ject was given three practice trials to become familiar with the procedure, for obtaining the reaction time and movement time scores. Following the practice trials, each subject completed a total of 45 trials including 15 simple auditory, 15 simple visual and 15 choice visual reaction time trials. These data were analyzed by the appropriate SPSS (Statistical Packaging for Social Science) program for the CDC 6500 computer at Michigan State University. Descriptive Statistics The means and standard deviations for each of the reaction time measures are presented in Table 4.1. These values were computed for each of the four subgroups. The results indicated that the motor-impaired boys enrolled in the Remedial Motor Clinic generally were Slower on all reac- tion time measures than the motorically normal boys in the Motor Performance groups. The mean values for the simple visual, simple auditory, and choice visual reaction time of motorically-impaired children all exceeded those of the normal children. In these cases, the higher values repre- sent slower reaction times. As indicated by the standard deviation figures, the performance of six and seven year old males enrolled in the Remedial Motor Clinic was more variable on Simple visual and choice reaction time, but less variable on auditory reaction time than boys of the same age enrolled in the Motor Perform- ance Study. The performance of 8 and 9 year old boys of the 34 Remedial Motor Clinic was less variable on simple auditory and choice reaction time than the comparison group of boys in the Motor Performance Study. However, both groups showed almost the same variability on simple visual reaction time. Table 4.1 - Means and standard deviations for the reaction time scores of boys enrolled in the Motor Performance Study (MP8) and the Remedial Motor Clinic (RMC) at Michigan State University. SVRT SART CRT Competency in _ Motor Behavior X SD X SD X SD Normal (MPS) 6-7 years 205.254 60.060 193.067 52.501 251.342 49.693 (N=16) 8—9 years 197.433 46.279 170.058 46.278 208.675 66.195 (N=16) Impaired (RMC) 6-7 years 254.429 73.411 196.017 48.216 273.221 50.301 (N=16) 8-9 years 224.992 46.242 199.650 35.098 249.392 50.784 (N=16) SVRT = Simple visual reaction time SART = Simple auditory reaction time CRT = Choice reaction time The boys classified as motorically impaired also showed higher mean scores for the three movement time measures, indi- cating that their movement time was Slower than that of normal boys (See Table 4.2). The standard deviation values for these 35 three variables also revealed that the children in the Re- medial Motor Clinic were more variable on movement times associated with simple visual reaction time and choice reac- tion time and less variable on movement time associated with auditory reaction time than their age peers in the Motor Performance Study. Table 4.2 - Mean and standard deviations for the movement time scores of normal boys enrolled in the Motor Performance Study (MP8) and the Remedial Motor Clinic (RMC) at Michigan State University. SVMT ' ' SAMT CMT Competency in Motor Behavior X SD X SD X SD Normal (MPS) 6-7 years 180.592 55.551 182.142 49.948 182.675 54.998 (N=16) 8-9 years (N=16) 133.679 30.566 125.421 49.285 143.783 44.230 Impaired (RMC) 6-7 years 194.912 66.780 197.858 49.592 218.587 58.148 (N=16) 8-9 years 176.238 57.689 181.063 36.790 175.417 47.317 (N=16) SVMT==Nbvemxu:tflmeassxfiatedvdth:finplexfisualxxactRXI tfimn SMflM=btwamxm;thmaasaxfiauxiwiflnSnmpheaudflxmylxactn31 tflML (lfl'==Bb~emauzthusassxdau31w131chouxeremfiiontime. 36 Inferential Statistics The data were analyzed by two-way analysis of var- iance to permit comparisons between children who are normal in their motor behavior and those who are motorically impaired or delayed as well as comparisons between age groups. Separate analyses were run for simple visual reac- tion time, simple auditory reaction time, and complex visual reaction time. In addition, movement time scores associated with each of the reaction time measures were also analyzed. The first hypothesis was that Simple reaction time and movement time performance scores of motor-handicapped children do not differ from those of motorically normal children. This hypothesis was tested through use of two— way analysis of variance based on 15 trials for each sub- ject under each stimulus condition. An alpha level of .05 was chosen to determine Significance. The critical region for rejection was reached when the value for F _>__ 4.00. Analysis of simple visual reaction time scores re- vealed that there was a statistically significant difference between the motor-handicapped boys and the normal boys (F = 7.096, see Table 4.3). The visual reaction time of the nor- mal boys was faster than that of the motor-handicapped boys. There was no significant age difference (F = 1.673) or interaction effects (F = 0.563) in visual reaction time. A significant difference also was found for the move- ment time responses associated with simple visual reaction time (F = 4.384, see Table 4.4). The movement times of the 37 males in the normal motor group were faster than those of the males with motor impairments. Significant age differ- ences in movement time also occurred (F = 5.829) with the older age groups moving faster than the younger age groups. When the interaction between age and program was considered, no significant difference was detected (F = 1.08). Table 4.3 - Two way analysis of variance results for simple visual reaction time. Source of Variation SS DF MS F P Motor Competency 23552.018 1 23552.018 7.096 1(05 Age 5552.734 1 5552.734 1.673 NS Interaction 1869.121 1 1869.121 .563 NS Error 199147.396 60 3319.123 Total 230121.269 63 Table 4.4 — Two way analysis of variance results for movement time associated with simple visual reaction time. Source of Variation SS DF MS F P Motor Competency 12940.958 1 12940.958 4.384 ($05 Age 17206.881 1 17206.881 5.829 (205 Interaction 3189.426 1 3189.426 1.080 NS Error 177115.643 60 2951.927 Total 210452.907 63 3340.522 38 Analysis of simple auditory reaction time scores (Table 4.5) failed to reveal any significant differences between the two motor competency groups (F = 2.00). Nor were there any Significant age group differences (F = 0.710) or interaction effects between age and motor competency (F = 1.34). Table 4-5 - Two way analysis of variance results for simple auditory reaction time. Source of Variation SS DF MS F P Motor competency 4235.840 1 4235.840 2.004 NS Age 1501.562 1 1501.562 .710 NS Interaction 2839.114 1 2839.114 1.343 NS Error 126819.670 60 2113.661 Total 135396.186 63 2149.146 The movement time scores obtained in conjunction with the Simple auditory reaction time measures were differ- ent for the motor-impaired males and the normal males (Table 4.6). The males with normal motor behavior performed signifi- cantly faster than the motor-impaired males (F = 9.325). Sig- nificant differences were also found between age groups (F = 9.898) with the 8 and 9 year old boys moving faster than the 6 and 7 year old boys. The interaction between age and com- petency was not significant (F = 2.92). 39 Table 4.6 - Two way analysis of variance results for move- ment time associated with simple auditory reaction time. Source of variation SS DF MS F p Motor competency 20368.047 1 20368.047 9.325 (.05 Age 21618.801 1 21618.801 9.898 ‘QOS Interaction 6376.022 1 6376.022 2.919 NS Error 131049.582 6O 2184.160 Total 179412.452 63 2847.817 In summary, the first hypothesis was that Simple reaction‘time and movement time performance scores of motor- handicapped boys do not differ from those of motorically normal boys. This hypothesis was supported by the results obtained for simple auditory reaction time. However, the hypothesis was not supported by the results obtained from simple visual reaction time and from the movement times associated with simple visual reaction time and with simple auditory reaction time. The interactions between age and motor competency in all cases were not significant. The second hypothesis that motorically normal males have faster choice reaction time and movement time than motor- handicapped males was tested by two-way analysis of variance. Alpha was set at .05 and an F value 2:4.00 was necessary to denote a significant difference. Analysis of choice visual reaction time scores re- vealed a significant difference between the normal males and 40 motor-handicapped males (F = 5.242, Table 4.7). The choice visual reaction time of the motor-handicapped boys was slower than that of the normal boys. Significant age dif— ferences were also found (F = 5.915) in favor of the older boys, but interaction effects were not significant (F = .475). Table 4.7 - Two way analysis of variance results for choice reaction time. Source of Variation SS DF MS F P Motor Competency 15672.953 1 15672.953 5.242 (105 Age 17686.783 1 17686.783 5.915 ‘QOS Interaction 1419.406 1 1419.406 .475 NS Error 179406.305 60 2990.105 Total 214185.448 63 3399.769 Movement time performances associated with choice visual reaction time were also significantly different for the normal boys and the motorically impaired boys (F = 6.886). The results were also in favor of the normal males (Table 4.8). Significant age differences also were obtained (F = 10.164), but there were no interaction effects (F = .028). The second hypothesis was supported by the results obtained in this study. The boys in Motor Performance Study performed faster on both choice reaction time and movement time than did the boys enrolled in the Remedial Motor Clinic. The third hypothesis was that the pattern of responses of normal children across trials for simple and choice reaction 41 Table 4.8 - Two way analysis of variance results for move- ment time associated with choice reaction time. Source of Variation SS DF MS F P Motor competency 18249.758 1 18249.758 6.886 (.05 Age 26937.016 1 26937.016 10.164 (205 Interaction 78.245 1 78.245 .028 NS Error 159017.094 60 2650.285 Total 204277.113 63 3242.494 time differs from the pattern of responses of motor- handicapped children. To test this hypothesis, the 15 trials for each subject were condensed into 5 blocks of 3 trials each. A mean for each block was then computed for each of the four subgroups. The results for each of the performance variables are presented in Figures 4.1 to 4.6,respective1y. A repeated measures or treatment by subjects design was used to analyze those graphs where the blocks means for a subgroup appeared to deviate from a straight line in order to determine whether or not the means of the 5 blocks were the same. An alpha level of .05 was chosen with an F valuegz 3.01 necessary for detecting a Significant difference. Figure 4.1 contains the block means for simple visual reaction time. The group with the most irregular pattern of means was that of the 6 and 7 year old boys in the Remedial Motor Clinic. The treatment-by-subjects analysis failed to Show a significant difference among the block trial means for 42 x-——I 6 and 7 yoor old motor-lmpolrod ooyo o—-—o 8 and 9 your old motor-impolrod boyo rum-x 6 and 7 yoor old normal boyo o----o 8 and 9 yoor old normal boys .50 — ’8 ‘1” 5 .40- _°/o\o/_’o cf ‘é’. a. h ‘~“ 2 \o- ____________ —o——-----4 9 30.. + .— 0 a m a: .20} T. j l I l l l 2 3 4 5 BLOCKS Figure 4.l - Mean Performance for Blocks on Simple Visual Reaction Time of Normal Boys and Motor-Impaired Boys. .40 - '6 I .30 "' ’* —————— * ...... 3 ‘- ------ a—-'"" I P o\ l- g . z —+ + g 2° .. ‘\\‘ 4 ° \ \ ‘o—-___ --+ ------ +-—- .“--O .Io‘t- t I I I I I I 2 3 4 5 BLOCKS Figure 4.2 - Mean Performance for Blocks on Movement Time Associated with Simple Visual Reaction Time of Normal Boys and Motor- Impaired Boys. 43 this group (F = .69, Table 4.9). It was concluded that the. pattern of responses of 6 and 7 year old motor-handicapped boys on simple visual reaction time did not differ from the pattern of responses of their normal peers. The movement time associated with simple visual reaction time for normal 8 and 9 year old boys was analyzed for differences among block means (See Figure 4.2). The treatment-by-subjects analysis Showed a significant differ- ence (F = 3.59, Table 4.9) between the means of the five blocks. Inspection of Figure 4.2 Shows that the first block of trials is different from the remaining four. Since the pattern of responses for the 8 and 9 year old normal boys was not linear, the responses of the motor- impaired boys in the same age group were investigated (Figure 4.2). There was no significant difference among the trial blocks for this group as indicated by the F value of .561 (Table 4.9). Therefore, it was concluded that the pattern of responses for movement time among normal and motor- handicapped 8 and 9 year old boys was not similar with the differences occurring during the first block of three trials. The performance of 6 and 7 year old motor-impaired boys on choice visual reaction time was analyzed (Figure 4.5) since the block means appeared to be dissimilar. How- ever, a non-significant F value of 2.11 was obtained (Table 4.9). Thus, it was concluded that the pattern of responses among the four groups depicted in Figure 4.5 was Similar 44 Table 4.9 - Repeated measures analysis (AOV) of the pattern of responses across trials. Reaction Time Movement Time Gm“? F P F 9 Simple Visual Normal 6-7 years * 8-9 years 3.59 ‘605 Motor Impaired 6-7 years .69 NS 8-9 years .561 NS Simple Auditory Normal 6-7 years 8-9 years Motor Impaired 6-7 years 8-9 years Choice Visual Normal 6-7 years .828 NS 8-9 years Motor Impaired 6-7 years 2.11 NS 3.88 (.05 8-9 years *The block means for those subgroups were not analyzed. 45 x—x 6 and 7 yoor old motor-impaired boys 0—0 8 and 9 year old motor-impaired boys x—---x 6 and 7 year old normal boys o—---o 8 and 9 year old normal boys .50 - ’5 8 v .40 - 11.1 E .— Z 2 '5 .30- 4 w I! .20; t l I I I T 1 2 3 4 5 BLOCKS Figure 4.3- Mean Performance for Blocks on Simple Auditory Reaction Time of Normal Boys and Motor- Impaired Boys. .40!- '3 C U V .30- Ill E |- 1- ‘ .N ‘4, E + ----- ‘7‘” ----- + ———— '2 u .20- N ______ 4 .— —————— -." ------ + ------ -." .IOJr ‘L I I I I I l 2 3 4 5 BLOCKS Figure 4.4 - Mean Performance for Blocks on Movement Time Associated with Simple Auditory Reaction Time of Normal Boys and Motor-Impaired Boys. .70- .60 '- .SOb REACTION TIME (sec) .401:- ‘L 46 x-—--x o----o 6 and 7 year old motor-impaired boys 8 and 9 year old motor-impairod boys 6 and 7 year old normal boys 8 and 9 year old normal bays k‘\ l”*““ ““ ”’ “* """" 4 ‘0’ I I I I I I 2 3 4 5 BLOCKS Figure 4.5 - Mean Performance for Blocks on Choice Reaction Time of Normal Boys and Motor - Impaired Boys. .50- .40 P .30- MOVEMENT TIME (sec) BLOCKS Figure 4.6- Mean Performance for Blocks on Movement Time Associated with Choice Reaction Time of Normal Boys and Motor - Impaired Boys. 47 and essentially linear in nature. Analysis of movement time associated with choice reaction time (Figure 4.6) indicated that the pattern block means for the 6 and 7 year old motor-handicapped boys was the most irregular. Analysis of the performance of this group revealed a Significant difference (F = 3.88, Table 4.9) between the means of 5 blocks. The responses of the normal 6 and 7 year old boys were then analyzed to see whether or not their performance scores on movement time associated with choice reaction time were linear. However, no difference was detected among the block means (F = .828, Table 4.9). The pattern of responses for the two groups of 6 and 7 year old boys thus differed. In- spection of Figure 4.6 indicates that the difference most likely occurred during the second block of trials. The third hypothesis that the patterns of responses of normal children for Simple and choice reaction time and movement time differ from the pattern of responses of motor-handicapped children was rejected in most instances. However, there were two exceptions. The response patterns were linear in nature except for the performance of the group of normal 8 and 9 year old boys on movement time associated with simple visual reaction time and for the performance of the group of 6 and 7 year old motor- handicapped children on movement time associated with choice reaction time. In these instances only one of the block trial means appeared to be dissimilar from the 48 remaining blocks. Of interest is the fact that these differences involved movement time. No differences in response patterns were evident among the groups for reac— tion time performance. Discussion The purpose of the study was to compare the simple reaction time, choice reaction time, and arm movement time of normal males enrolled in the Motor Performance Study with motor-handicapped males attending the Remedial Motor Clinic at Michigan State University. Reaction Time The results of this study support the generalization that motor-handicapped children are slower than normal children on both simple and choice reaction time. How- ever, in this study the performance of the motor- handicapped boys was equal to that of normal males in simple auditory reaction time. A search of the liter- ature failed to uncover any previous studies that assessed the reaction time of motor-impaired children, therefore the validity of the results of this study must await further investigation. Several studies that assessed the reaction time of mentally impaired subjects were located. Since motor- impaired children and mentally impaired children both represent special populations, some comparison will be made between these groups. 49 The results of this study partially support the findings of investigators who have studied the simple reaction time of mentally impaired children. Studies conducted by Berkson and Baumeister (1967); Jones and Benton (1968); Bonsell, Ross and Kelly (1969); Kellas (1969); and by Baumeister and Kellas (1972) all indicate that mentally impaired subjects are slower and more var- iable than normal subjects on measures of reaction time. In the current study, the motorically impaired subjects were slower than their normal counterparts on visual reaction time, but equal to them on auditory reaction time. In addition, variability as measured by the pattern of responses was the same for both the motor-handicapped boys and the normal boys. Thus, the performance of the motorically impaired subjects was similar to that of mentally impaired subjects, when compared to normal sub- jects, only on measures of simple visual reaction time. The Slower performance of motor handicapped subjects on visual choice reaction time is also found when the per- formance of mentally impaired subjects is compared to that of normal subjects. The results obtained by Jones and Benton (1968) and Gafrey, Jones and Hinkle (1971) in sepa- rate investigations showed mentally impaired subjects to be significantly inferior to normal subjects on tasks in— volving visual choice reaction time. The literature generally supports the notion that reaction time improves with increasing age until maturity 50 is reached and subsequently deteriorates with old age (Bellis, 1933; Pierson, 1957; Mendryk, 1960; Hodgkins, 1962). The current investigation showed age differences for choice reaction time, but not for the simple reaction time measures. A plausible explanation for the failure to obtain age differences on the simple reaction time mea- sures is the restricted age range (four years) used in this study. A comparison of subjects who are six or seven years of age to those who are eight or nine years old on measures of simple reaction time may not provide a sufficient time span for developmental changes to manifest themselves on tasks of low difficulty. In contrast, a two year interval may be of sufficient duration to detect developmental changes associated with performing tasks that place greater demands upon the decision making processes in the central nervous system. Compared to the age range of the subjects included in this study, Bellis (1933) used subjects rang- ing in age from 4 to 60 years; Mendryk (1960) tested groups of males who were 12, 22 and 48 years of age, respectively; Hodgkins' (1962) subjects were females 6 to 84 years of age; and Pierson (1957) studied males between the age of 8 and 83 years. Movement Time The results of the present study clearly indicated that motorically normal boys have faster movement time than motor-handicapped boys. These results pertain to movement time associated with simple reaction time and to movement 51 time associated with choice reaction time. Thus the motor- handicapped child not only reacts more slowly in some stim- ulus settings but also moves slower than his normal counter- part. This may contribute to the syndrome of clumsiness associated with the motorically impaired youngster. No studies were found in the literature that compared the move- ment time of normal subjects with handicapped subjects. Significant age differences in movement time were obtained on all three measures taken. In each instance the older boys moved faster than the younger boys. These results are in agreement with the findings of Bellis (1933) and Pierson (1957). The pattern of responses across trials for movement time was Similar for normal and motor-impaired boys in four of six comparisons (see Figures 4.2, 4.4, 4.6). In two in— stances, the response patterns of the boys deviated from a linear model. This occurred with the 8 and 9 year old nor- mal boys on movement time following simple visual reaction time and with the 6 and 7 year old motor-handicapped boys on the movement time associated with choice reaction time. Thus there was no particular trend favoring either the normal or the motorically impaired subjects in the pattern of responses across the fifteen trials when grouped by blocks of three trials. CHAPTER V SUMMARY, CONCLUSION, AND RECOMMENDATIONS Summary The purpose of the present investigation was to compare the simple reaction time, choice reaction time and arm movement time of normal children enrolled in the Motor Performance Study at Michigan State University with motor- handicapped children attending the Remedial Motor Clinic at Michigan State University. Two groups of male children ranging in age from 6 to 9 years were involved in the study. Each group of 32 subjects was divided by age into two sub- groups consisting of 6 to 7 year and 8 to 9 year old boys, respectively. Each subject was given three trials to become familiar with the procedures for obtaining the reaction time and movement time scores. Following the practice trials each subject completed a total of 45 trials including 15 Simple auditory, 15 simple visual, and 15 choice visual reaction time trials. Data were analyzed by two-way analysis of variance to detect any significant difference in the performance of normal boys and motor-handicapped boys on simple visual re- action time, simple auditory reaction time and choice reac- tion time tasks. Analysis of data indicated that normal boys 52 53 were significantly faster than motor-impaired boys on the measures of simple visual reaction time and choice reaction time, but the two groups of boys performed equally on simple auditory reaction time task. Age differences in performance were not Significant on simple visual reaction time and audi- tory reaction time.but were significant on choice visual reaction time. Interaction effects were not significant for any of the three measures of reaction time. When movement time performances were analyzed by two- way analysis of variance, significant differences between the normal boys and motorically impaired boys were obtained in favor of normal boys. These differences occurred for movement time associated with simple visual reaction time, with simple auditory reaction time, and with choice visual reaction time. Significant age differences in performance were also obtained for each measure of movement time, but interaction effects were not significant for any of the three movement time measures. Graphs depicting performance patterns in blocks of three trials were constructed for each group on simple visual reaction time, simple auditory reaction time,choice visual reaction time, and the movement times associated with each of the three measures of reaction time. A repeated measures or treatment-by-subjects design was used to analyze the graphs. Analysis of the graphs showed that the patterns of performance were consistent between the normal boys and motor-handicapped boys on Simple reaction time and choice reaction time, but were 54 inconsistent on movement time associated with simple visual reaction time and movement time associated with choice reac- tion time. Conclusions The following conclusions are drawn from the data within the limitations of this study: 1. The simple visual reaction time and the choice visual reaction time of the normal boys was significantly faster than that of the motor- handicapped boys. The Simple auditory reaction time scores of motor-impaired boys was not significantly different from that of the normal boys. The performance of the motorically normal males was superior than that of the motor- impaired males for movement time following simple visual reaction time, simple auditory reaction time and choice visual reaction time. Age was not a factor in performance for simple visual and simple auditory reaction time, but it was a significant factor on choice reaction time performance. Age was a significant factor in performance for all movement time responses. No interaction effects between age and motor competency occurred for any of the six depen- dent measures. The pattern of responses of the normal boys across trials for simple reaction time and choice reaction time did not differ from that of the motor-handicapped children. The pattern of responses across trials of the normal boys for movement time generally was not different from the pattern of responses for the motor-impaired males, except in two instances. The group of 8 and 9 year old normal males was more variable on movement time following Simple visual reaction time than the group of 8 and 9 year old motor-handicapped children; and the The research on 1. 55 performance of the 6 and 7 year old motor- impaired boys on movement time associated with choice reaction time was more variable than that of the 6 and 7 year old normal boys. Recommendations following suggestions are offered for future the problem investigated in this study: Since both groups performed the same on the Simple auditory reaction time task, but not on the Simple visual reaction time, task, this study should be repeated using larger sample sizes to determine if these results have ex- ternal validity or if they were unique to the subjects in this study. In this study the data was collected from male subjects only, therefore replication of the study Should occur using both male and female subjects. , The subjects in the present study were chosen from a small number of subjects and a re- stricted age range (6 - 9 years). It is recom- mended that a larger number of subjects at each chronological age and across a wider age range be studied to determine where the differences in reaction time occurs. On the choice reaction time task, the subjects had to react to one of the three different colored lights. The presence of color blind subjects at any of the groups was not deter- mined. In future studies, if colored lights are used, the color vision of the subjects Should be determined prior to testing to assure equal stimulus settings for all sub— jects. The effect of the length of the pre-stimulus interval and the nature of the pre-stimulus warning signal on the reaction time and move- ment time of motorically impaired children should be studied. 6. 56 A more complete analysis of the pattern of responses for reaction time should be made. Analysis Should include individual trial performances rather than blocks of trials and should extend across all subgroups. BIBLIOGRAPHY 10. BIBLIOGRAPHY Alken, L. R. and Lichtensten, M. Reaction Times to Recurring Visual Stimuli. Perceptual and Motor Skills, 1964, Vol. 18, pp. 713-720. Baumeister, A. and Kellas, G. Distribution of Reaction Time of Retardates and Normals. Am. J. of Psychology, 1968, Vol. 72, pp. 715-718. Bellis, C. J. Reaction Time and Chronological Age. Proceedings of the Society for Experimental Biology and Medicine, 1933, Vol. 36, pp. 801-803. Berkson, G. and Baumeister, A. Reaction Time Varia- bility of Mental Defectives and Normals. Am. 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Perceptual and Motor Skills, 1974, Vol. 38, pp. 417-418. APPENDIX APPENDIX Table A.1 - Repeated measures for analyzing the pattern of responses of 6-7 year old males in the Remedial Motor Clinic on simple visual reaction time. Source of Variation SS DF MS F P Total 18246.56 79 Subjects 10293.20 15 Treatments 350.85 4 87.71 .69 NS Error 7602.54 60 126.71 Table A.2 - Repeated measures for analyzing the pattern of responses of 8-9 year old males in the Motor Performance Study on movement time associated with Simple visual reaction time. Source of Variation SS DF MS F P Total 19993.68 79 Subjects 1010.24 15 Treatments 234.13 4 58.53 3.59 (05 Error 976.60 60 16.30 61 62 'Table A.3 — Repeated measures for analyzing the pattern of responses of 8-9 year old males in the Remedial Motor Clinic on movement time associated with simple visual reaction time. Source of Variation SS DF MS F P Total 9568.90 79 Subjects 7775.46 15 Treatments 62.41 4 15.60 .56 NS Error 1731.03 60 28.85 Table A.4 - Repeated measures for analyzing the pattern of responses of 6-7 year old males in the Remedial Motor Clinic on choice reaction time. Source of Variation SS DF MS F P Total 16434.00 79 Subjects 10031.92 15 Treatments 789.40 4 197.35 2.11 NS Error 5612.68 60 93.55 63 Table A.5 - Repeated measures for analyzing the pattern of responses of 6-7 year old males in the Remedial Motor Clinic on movement time associated with choice reaction time. Source of Variation SS DF MS F P Total 13775.32 79 Subjects 8376.49 15 Treatments 111.37 4 277.84 3.88 (.05 Error 4287.45 60 71.46 Table A.6 - Repeated measures for analyzing the pattern of responses of 6-7 year old males in the Motor Performance Study on movement time associated with choice reaction time. Source of Variation SS DF MS F P Total 12527.50 79 Subjects 7102.83 15 Treatments 284.05 4 71.01 .83 NS Error 5140.64 60 85.68 111111111111111“