M W W \ '_—’ i < _'—— —_ fl ’4’ WW 1 I W \ \l A MEASURE ‘3‘? H}? FREQUENCY ANS HIT DURATWN EN ROTARY PGRS-Ul'!’ WRKWMANCE UNDER ALTfiRNAYE CONDSTIQNE C}? DEfi'i'RiEUTEE} AND MASSED P‘RACTECE Thesis 270:: Mm» Dogma 0'5 M. A MECHEG'. N S‘YATE Ul'ii‘ffiiifl‘f‘f gamma erm’d Xmas {96:23 ABSTRACT A MEASURE OF HIT FREQUENCY AND HIT DURATION IN ROTARY PURSUIT PERFORMANCE UNDER ALTERNATE CONDITIONS OF DISTRIBUTED AND MASSED PRACTICE by Roberta Greenall Koons Seventy-two subjects practiced the rotary pursuit task with simul- taneous visual feedback from a band of light forming a continuous rectangu- lar border around the rotor base. Subjects practiced on a 60 rpm clock- wise rotor for two six-minute periods separated by a five-minute rest under one of four distribution schedules: M-M, M-D, D-D, and D-M. Massed practice was continuous and distributed practice was made up of alternate intervals of 30-seconds work and 30-seconds rest. Two per- formance measures were recorded for each 30-second trial: total time on target and number of hits. The number of hits was recorded by the use of a hit counter which was activated whenever the stylus was in con- tact with the target. From these two measures a derived index of mean hit duration was computed for each 30-second trial. Using the three measures, rotary pursuit phenomena were examined in regard to the on-target aspects of performance and their relationships to the constructs of temporary inhibition, conditioned inhibition and warm- up. In addition, the effect of simultaneous visual feedback on performance was evaluated. It was found that 1. The typical superiority of distributed practice conditions for both pre- and post-rest practice is evident in on—target measures as well as in total time on target. 2. 3. 4. Roberta Greenall Koons Each of the massed groups shows significant reminiscence gain in hit duration, however the massed group does not differ significantly from the distributed group which shows no signifi- cant gain. F or number of hits and percent time on target there is a significant amount of reminiscence for all groups and the gain in the massed condition is significantly greater than'in the spaced. Temporary inhibition clearly is related to the number of hits measure and questionably related to the hit duration measure. Only the unchanged distribution condition groups (DD, and M-M) show significant warm -up in percent total time on target; however, these groups do not differ significantly from the changed distribution groups (D-M and M-D) on any of the three measures: hit frequency, hit duration, or total time on target. All but the D-D group show significant warm—up in hit duration together with a decrease, or no change, in hit frequency. The D-D group did not show warm -up in either hit duration or hit frequency. During post-rest practice the number of hits stabilized and decreased while the duration of hits increased for the D-D group. For the M-D group hit durations increased steadily, while the n umber of hits stabilized in the first three minutes and then fluctuated. The M-M group showed an inverse re- lationship between regularly decreasing hit frequency and generally increasing hit durations until the fourth minute of post-rest practice when durations dropped to a low and Approved: Roberta Greenall Koons stable level. Hit frequencies for the D-M group consistently decreased while hit durations dropped after the first three minutes of post-rest practice. On all three measures there was convergence between groups practicing under like conditions after rest. This adds support to an explanation of the extinction (M-D) and conditioning (D-M) of conditioned inhibition, even though hit durations in the M-D group did not quite overlap the level of the D-D group. Conditioned inhibition, the difference in performance between D and M groups on the first post-rest trial, is clearly related to shorter hit durations in the massed practice groups. The simultaneous visual feedback cue depressed performance during both practice periods, and this depressing effect was greater for distributed practice conditions. age, flaw Professor of Psylyhology fl/Q/ZL 2 7 4C) my / / A MEASURE OF HIT FREQUENCY AND HIT DURATION IN ROTARY PURSUIT PERFORMANCE UNDER ALTERNATE CONDITIONS OF DISTRIBUTED AND MASSED PRACTICE BY Roberta Greenall Koons A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF ARTS Department of Psychology 1962 and three for Iris, and ... CHAPTER I II III IV TABLE OF CONTENTS IntI'OdUCtIODoooooooooooooooooo Measuring "on-target" behavior. . . . . . . . Status of phenomena in pursuit rotor performance Inhibition constructs . . . . Visual feedback '. . . . . . ‘ Statement of the problem . . Method........... Subjects...... Apparatus . . . . . . A. . Experimental design. . . . PIOCCdUIeooooooooo RESUItSoooooooooooooo Initial performance . . . . . . Pre -rest distribution of practice Reminiscence. . . . . . . . . Initial post-rest trial . . . Warm-up. o o o o o o o Post-rest practice period . Convergence . . . . . . Visual feedback . . . . . Discussion Measures of hits Dissipation of temporary inhibition Conditioned inhibition . . . Wrm-up......... Visual feedback . . . . . . Summary.......... References iii PAGE I—d OOCDrhWi—I 12 12 15 l6 l8 18 22 25 28 28 34 38 42 42 43 43 45 48 50 LIST OF FIGURES FIGURE PAGE I Comparison of three response measures . . . . . . . 19 II Comparison between the Frisbey (1952) and Koons data for post-rest distributed conditions . . . . . . . . . 39 III Comparison between the Frisbey (1952) and Koons data for post-rest massed conditions . . . . . . . . . . . 40 iv LIST OF TABLE S TABLE PAGE 1 Distribution of practice schedule . . . . . . . . . . . . 13 2 Means and standard deviations for four groups on three measures of the first 30-second period of practice . . . . 20 3 Analyses of variance between four groups on three measures of the first 30-second period of practice . . . . 21 4 Means and standard deviations for four groups on three measures of the last 30-second period of pre-rest practice. 23 5 Analyses of variance between four groups on three measures of the last 30-second period of pre-rest practice . 24 6 Mean reminiscence scores over the five -minute rest periodforthreemeasures. . . . . . . . . . . . . . . Z6 7 Analyses cfvariance between four groups on three measures of reminiscence gain over the five-minute rest period . . 27 8 Means and standard deviations for four groups on three measures of the first 30-second period of post-rest Praeticeooo00000000000000.0000. 29 9 Analyses of variance between four groups on three measures of the first 30-second period of post-rest practice . . . . 30 10 Mean warm -up scores derived from the first two trials of post-rest practice for three measures . . . . . . . . 32 ll Analyses of variance between four groups on three measures of warm -up taken as the difference between the first two trials of post-rest practice . . . . . . . . . . . . . . 33 12 Means and standard deviations for four groups on three measures of the last 30-second period of post-rest practice. 36 13 Analyses of variance between four groups on three measures of the last 30-second period of post-rest practice . . . .‘ 37 LIST OF APPENDICES APPENDIX PAGE I Individualdatasheet................52 H Statistical design of the analyses of variance . . . . . 54 vi CHAPTER I INTRODUCTION For several reasons pursuit rotor learning has been recognized as a useful focus for systematic investigation into the processes involved in human motor behavior. It offers a miniature behavior system that is not impossibly complex, which allows for the isolation of a number of variables and the checking of a variety of hypotheses. At the same time the situation is novel to the learner and relatively constant from subject to subject. 1. Measuring "on-target" behavior. Recent research has been directed toward analysis of the skills demanded by the tracking task and toward explanation of the fluctuations in performance during practice periods. Measuring rotary pursuit per- formance in terms of the number and temporal patterning of hits provides information about the nature of the skills involved that is not available from the customary single measure of total time on target per trial (Ammons, 1951; Archer, Kent, and Mote, 1956; Bourne and Archer, 1956). In such analyses of motor performance two procedures have been used for measuring the frequency and duration of hits on each trial -- kymographic and electronic recording. Ammons (1951) found the method of kymographic recording inefficient, since it required a time -consuming operation of data translation from indi- vidual records, up to twelve to fifteen hours per subject. In addition to total time on target, measures of .frequency and mean duration of hits as well as mean duration of misses for each trial were obtained. In his study massed and distributed groups each received twelve minutes of practice. 1 2 It was found that: (a) number 3f l_}_i_t_s is greater during distributed practice; (1)) number of hits rises quickly to a rather stable maxi- mum level during distributed practice but increases slowly through- out continuous practice; (c) mean duration of hit_s_ is greater during distributed practice; ((1) mean duration of his—shows a negatively accelerated increase during practice for—bo—th- groups . . .(Ammons , 1951, p. 22). Ammons (1951) suggests, on the basis of his data, that learning may involve three types of behaviors: (1) increasing skill in making circular, sweeping movements of both eye and hand; (2) increasing skill in making more efficient corrective movements; and (3) increased sensitivity to a greater number of error cues. As Ammons noted, there is a ceiling for themaximum number of hits possible, since the increase in duration of hits, as practice continues, limits the frequency of hits. Ammons predicted that a reduction in number of hits would be found for a distributed condition for a practice period longer than the 12 minute period he employed. Refine- ment of tracking accuracy, then, would be indicated by hits decreasing in number while increasing in duration. Bourne and Archer (1956), using an electronic measurement pro- cedure, recorded directly the frequency distribution of,hits among several duration intervals. They found that the frequency of hits increased during early stages of learning. They considered that their negatively accelerated curves for hit frequency partially substantiated their hypothesis that hits would decrease during later practice periods. However, the 10.5 minutes of practice they employed was not sufficiently long to show the actual de- crease that Ammons (1951) had predicted. Bourne and Archer (1956) found that the hit durations increased, generally, and hits of very long duration (over one second or one revolution) began to appear as practice proceded. They felt that these data indicated two separate learning phases, similar to those described by Ammons (1951), 3 are involved in the tracking task: first, getting on target (number of hits) and later, staying on target (duration of hits). The total time on target measure simply does not permit the inde- pendent identification of these two components of the tracking response. However, Ammons' indices (1951) appear to reflect these components as well as Bourne and Archer's classification of hit patterns (1956), though the modal duration and proportion of extremely long hits are obscured. It should also be possible to compute an index roughly comparable to Ammons" derivative measure of mean-duration-of- hits -per-tria1 simply by dividing time on target per trial by the number of hits per trial. It is possible that an index of mga_n hit durations so computed might be less sensitive to change than Ammons' index (1951), though possibly less accurate than a group median as an estimate of the distribution of hit durations per trial. 2. Status of phenomena in pursuit rotor performance. The characteristic phenomena in pursuit rotor performance are re- lated to the factor of distribution of practice. (a) Performance is better under a spaced practice schedule than a massed practice condition. This applies to number and duration of hits as well as to total time on target. (b) An improvement in performance without additional practice (reminiscence) appears after a rest period. Moreover, a pre -rest massed practice condition customarily produces significantly more reminiscence than a pre -rest distributed condition (Denny, Frisbey and Weaver, 1955, which reports data from Frisbey, 1952). This reminiscence effect appeared as an increase in both number of hits and duration of hits in the Bourne and Archer (1956) study. (c) After an interpolated rest interval a significant post-rest 4 difference in initial performance between massed and spaced conditions has been found inmanystudies (eg.: Bourne and Archer, 1956; Denny, et a1, 1955). On the other hand, some studies (Adams and Reynolds, 1954; Archer, 1954) have not found that massed practice groups remain significantly poorer than distributed practice groups. (d) There is a warm -up effect, or marked increase in performance scores for the first few post-rest trials. Although Bourne and Archer (1956) reported finding no significant warm-up, all distributed groups were given massed practice following rest. Unfortunately they presented no quali- tative analysis of the changes in number of hits or mean duration of hits during the first few trials after rest. MoreOver, the measures of number of hits were combined for the first three post-rest trials, which precludes any inference from their data regarding warm-up. Ammons and Willig (1956) suggest that warm -up may interact with distribution conditions, while Adams’ data (1955) indicate that rest interval activities may affect warm-up. (e) After a shift in conditions convergence has been found for groups practicing under like conditions following a single rest period (Frisbey, 1952), suggesting that the effects of massing and spacing are not permanent. For a shift from D to M conditions, Bourne and Archer (1956) found that there was a return to shorter hit durations and a decrease in number of hits to- ward the level of the post-rest M-M condition. 3. Inhibition constructs. From Hullian theory two inhibition constructs have been posited by Kimble (1949a, 1949b) to account for performance depression. One con- cept is reactive inhibition, IR , which is considered to be a temporary nega- tive drive state that is response produced and dissipates spontaneously during rest. Conditioned inhibition or SIR, which is the second concept, 5 is a learned resting habit conditioned to stimuli associated with resting. 'I'he resting response reduces IR and therefore is reinforced by dissipa— tion of IR. As a habit SIR seems to be consistent with the learning prin- ciples of acquisition and extinction; it does not dissipate spontaneously, but may undergo extinction gradually (Denny, et a1, 1955). The two con- cepts are considered to be intimately interrelated and have been related specifically to number of hits and miss duration by Ammons (1951). Ammons proposes that the shorter durations of hits during continuous practice reflects the accumulation of reactive inhibition, commenting that Once a critical level of reactive inhibition (need to rest) is built up, resting will occur until the amount of reactive inhibition drops below the critical level (Ammons , 1951, p. 21). A critical level of reactive inhibition should, therefore, be reflected by shorter duration of hits, longer time off target, and hence fewer hits. Bourne and Archer's data (1956) for both pre- and post-rest are compatible with this . Ammons' theory of pursuit rotor learning (1947) posits two variables— temporary, and permanent work decrement -- essentially identical with the constructs of temporary inhibition (IR) and conditioned inhibition (SIR) noted above. In addition Ammons proposes a third decremental construct to explain the initial abrupt rise in post-rest performance. This "warm— up' decrement is attributed to the need to regain set after rest whether or not the change in performance level over rest represents an actual decrement. On the basis of finding little or no evidence of permanent work decre- ment after 90 minutes of work by a massed practice group Ammons and Willig (1956) now espouse a stimulus maturation theory of pursuit rotor learning, also proposed by Bell (1942) and Hilgard and Smith (1942) , and state that the ...theoretical formulations dealing with inhibition phenomena quite possibly stand in need of extension or revision. It may be that conditioned inhibition. ..is an unnecessary construct 6 and that the phenomena referred to can be accounted for in other ways (Ammons and Willig, 1956, p. 125). To account for the markedly greater decremental trend in the per- formance of a group shifted from spaced to massed practice in comparison to a group continuing to work in blocks of massed practice, Ammons and Willig (1956) propose three possibilities: (a) Ss with relatively distributed practice have had less opportunity to develop habits for responding efficiently when large amounts of reactive inhibition are generated; (b) Ss with distributed practiCe rapidly lose motivation when they are given a long period of continuous practice; (c) the stimulus becomes increasingly different from that present during acquisition of the most adequate responses, and consequently fewer and fewer of these are elicited (Ammons and Willig, 1956, p. 124). Independently, Bourne and Archer (1956) have also reached the con- clusion that there may be only one kind of inhibition. From their view- point, temporary inhibition is considered to interfere with learning as well as performance although they comment that their data might be interpreted also as evidence for the existence of conditioned inhibition. They suggest that what has been termed permanent work inhibition is simply a poorer level of learning .of smooth, circular tracking that results from the inter- ference effect of temporary inhibition. This opinion is based on their analysis of on-target behavior. At the outset of practice, nearly all the hits made by 53 are of short durations, indicating an inability to remain on target. As practice continues, the groups differentiate in ability to make longer hits , i.e. , to make coordinated circular movements. The initial post-rest difference is due primarily to the difference in level of skill which varies in accordance with the length of inter- trial interval and the amount of inhibition sustained. Under con- ditions of massed practice, this difference is eliminated and there is a shift back to less coordinated pursuit with an accom- panying increase in short-duration hits. An hypothesis of this 7 general nature would eliminate the need for a construct of per- manent work decrement or conditioned inhibition (Bourne and Archer, 1956 , p. 32. Italics mine). Since the Bourne and Archer (1956) study was not designed to con- trol for the interaction between decremental effects and distribution of practice conditions (all groups received massed practice following rest), their interpretation of inequalities in learning would require further ex- perimental test. Moreover, Ammons and Willig's (1956) M and D con- ditions show approximately equal terminal proficiency after approximately equal practice. This finding, as well as their postulations of stimulus maturation and stimulus change, argues against a poorer learning expla- nation. In addition, Denny et a1 (1955) point out that a "poorer learning" hypothesis would have to assume differential increments to learning in order to account for convergence following a shift to distributed conditions following rest. The Denny et a1 (1955) data support both IR and SIR constructs. The absence of a differential warm-up between massed and distributed conditions on the initial post-rest 30-second trial in their data helped make possible an analysis which indicated that the difference between D-D and M-D during post-rest practice consisted wholly of conditioned inhibition. In their theory the unconditioned stimulus for establishing conditioned inhi- bition is the massed practice condition, and the removal of massing by shifting to distributed conditions means the removal of the unconditioned stimulus. Accordingly, the converging of D-D and M-D was interpreted as representing extinction of SIR. With such a wide divergence of opinion an examination of on-target hitting behavior of post-rest distributed groups seems desirable and should add to the findings of Bourne and Archer (1956) and our understanding of inhibitim phenomena . 4. Visual feedback. The effect of introducing visual feedback of information to a subject during practice has not been studied. It might serve as an incentive, or as additional reinforcement or an an aid to discrimination. On the other hand, visual inhibition has been found to be a major component of work decrement in the pursuit rotor response (Adams, 1953). Therefore, it is also possible that visual stimulation might serve as a distractor enhancing the develop- ment of inhibition and not facilitating learning. An exploration of visual feedback might suggest the nature of its influence on rotary pursuit per- formance . 5. Statement of the problem. The present study is concerned with: (1) three constructs which have been postulated to account for rotary pursuit phenomena -- temporary inhibition, conditioned inhibition, and warm-up; and (2) two measures of on-target aspects of rotary pursuit performance - number of hits and esti- mated mean hit duration. Consideration of the foregoing discussion suggests that certain exploratory questions may be raised in an attempt to clarify the issues stated above. 3|: t It * It 1: It A continuing critical level of reactive inhibition in massed practice conditions should be reflected in fewer hits and shorter hit durations than in distributed conditions (Ammons , 1951). Therefore, for 1. Pre-rest distribution of practice: Will the typical superiority in pre ~rest performance of groups working under distributed conditions in contrast to groups working under massed conditions be found for on-target measures as well as for total time on target? 9 3|: * 3|: t * * II: Dissipation of temporary inhibition should be reflected by an in- crease in both number and duration of hits (Bourne and Archer, 1956). Therefore, for 2. Reminiscence: Will on-target measures, as well as the measure of total time on target, show more reminiscence present in the massed groups, than in the distributed groups after an equal amount of rest, when measured over a 30-second period of practice? For the 3. Initial post-rest trial: Will the difference between massed and spaced con- ditions on the first post-rest trial be significant in the present data for on-target measures as well as for time on target? A finding of shorter hit durations in the massed practice groups could be interpreted as reflecting either SIR (Denny, et a1, 1955) or poorer learning (Bourne and Archer, 1956). t * 1k t t t * Un changed practice conditions (D-D and M-M) might be inferred to be more conducive to reinstating set than might conditions where there is a different practice schedule following rest (D-M and M-D) (Ammons and Willig, 1956). Also for the D-M group the decremental operation of undissi- pated inhibition, built up during the initial 30-seconds of post-rest practice, is introduced into the second 30-second work period and should interfere with the regaining of set (Denny, et al, 1955) . Therefore, for 10 4. Warm-up: Will both on-target measures as well as total time on target show a performance increment from the first to the second post-rest trials in groups practicing under unchanged conditions greater than that of groups working under a different temporal schedule following rest? A at t I t t at * Later learning should involve improvement in the smooth tracking response component of rotary pursuit skill; i.e., staying on target (Ammons , 1951; Bourne and Archer, 1956). Therefore, for the 5. Post-rest practice period: Will the number of hits stabilize or decrease while duration of hits increases, during the post-rest practice period, at least for the distributed practice condition? For both D-M and M-M groups the operation of IR may preclude or con- ceal this inverse relationship. Moreover, the overall length of the practice sessions may be too short for this phase of learning to be seen clearly. * t t l! t I: II: On the basis of the Frisbey (1952) study it is expected that the effects of massing and spacing of practice are not permanent. Therefore, for 6. ’Convergence: Will groups practicing under like conditions, after the variable of distribution of practice has had a chance to operate in post-rest performance, converge and remain together so that at the end of the post-rest period dis- tributed groups (D-D, M-D) will be superior to massed groups (M-M, D-M) on the total time on target measure? tsetsss 11 If convergence of groups practicing under like conditions after rest is due to: (1) the development of inhibitory potential in the distributed- massed (D-M) group, and (2) the extinction of conditioned inhibition in the massed-distributed (M-D) group, then for 7. Convergence in on-target measures: Will both duration of hits and number 'of hits measures converge by the end of the post-rest practice session for groups practicing under like conditions? A comparison of the final post-rest on-target measures for the M-D and D-D groups may provide some information regarding the issue of whether the lower level of performance during massed practice is a function ’of poorer learning (Bourne and Archer, 1956), or of conditioned inhibition (Denny, et a1, 1955). it t it it II t * As the earlier discussion indicated, the effect of introducing an additional visual cue into the rotary pursuit learning situation is impossible to predict. However, for 8. Visual feedback: Will a visual feedback cue occuring simultaneously with each stylus -target contact have a facilitating or decremental effect on rotary pursuit performance? In order to evaluate this issue, data obtained under the visual feedback cue condition will be examined graphically in comparison with data from Frisbey (1952). CHAPTER II METHOD 1. Subjects. A sample of 72 college students served as subjects. 70 Ss were drawn from courses in introductory psychology and methods of effective study, while 2 88 were graduate students. All were volunteers with no previous pursuit rotor experience. Half of the 83 were male, half were female, and they ranged in age from 17 to 26 years. The mean age was 20.4 years. The records of four additional Ss were rejected; two were invalidated by power failure during the experiment; one showed no im- provement in performance at any stage of practice; and the initial per- formance of the fourth S was markedly superior to the initial scores in all other records. The first forty subjects were assigned randomly to one of four ex- perimental conditions. No qualifications then were placed on the allo- cation of succeeding Ss , namely: (1) the proportion of men and women was kept equivalent among the four groups, and (Z) the initial 30 seconds of performance served as a basis for assignment of each S to a given ex- perimental condition in order to equate the groUps to each other and to the sample used by Frisbey (1952). Allocation was accomplished without interrupting the practice session. The description of Ss is included in Table 10 2. Apparatus. The apparatus consisted of a Koerth-type pursuit rotor, calibrated to 60 rpm, which turned in a clockwise direction; a hinged stylus, a double- throw four pole toggle switch, two Standard Electric timers which measured 12 Table I Distribution of practice schedule 6 min 5 min 6 min Number of subjects Mean age Group practice rest practice male female totEI in years D-D D - D 9 9 18 20.2 D-M D - M 9 9 18 20.5 M-M M - M 9 9 18 20.9 M-D M - D 9 9 18 20.0 Total 36 36 72 20.4 Frisbey (1952) 28 36 64 20.6 13 14 to the nearest 0.01 second the time on target, a cumulative counter for re- cording the number of hits, and a stopwatch. The rotor disc, of .25 inch black bakelite was 28.5 cm in diameter with a circular brass target 1.9 cm in diameter set flush with the larger disc, and 8.5 cm from its center. The rotor disc was set flush with its housing. The rotor was surrounded by a box frame 42.9 cm square by 14.2 cm high, with an open top level with the pursuit rotor disc. Two 8-unit sets of green 7.5 watt Christmas tree lights were mounted inside the frame. The open top was then covered by translucent green paper. This gave a diffuse halo of green light surrounding the pursuit rotor whenever the stylus was in contact with the target. The lights and counter were on one circuit and the clocks were on a second circuit to minimize the drain on the line and thus avoid voltage drops. Both circuits were activated simultaneously by a 120 v. G. E. relay, which was in turn activated by a stylus -target completion. [The noise level was increased for stylus -target contacts as a result of the added relay and counter. In addition, therrelay emitted a continuous hum audible through- out the experimental session. The equipment was mounted on a wooden table 30 inches high; the surface of the rotor disc, therefore, was 36 inches above the floor. The edge of the frame surrounding the rotor was about two inches from the edge of the table, thus placing the housing of the rotor about 5 inches from the table edge. Room illumination was reduced to enhance the effect of the "halo- light" . The only light in the room was provided by a 25 watt bulb mounted in a flexible cable lamp (student-type desk lamp) placed on a table in the corner of the room about four feet in front of, and to the right of, the sub- ject. The lamp illuminated the lower half of the walls and the table surface, 15 providing only indirect lighting for the surface of the rotor. 3. Experimental design. The total practice time was divided into two sessions of six minutes each, separated by a rest period of five minutes. Massed practice (M) consisted of continuous practice during a six-minute session, while distribu- ted or spaced (D) practice consisted of 12 alternating intervals each of 30 seconds of work and 30 seconds of rest. The conditions under which one of each of the four sub-groups practiced during the two work periods were: D-D, D-M, M-M, or M-D. The lengths of the initial practice session, the rest period and the work and rest intervals were selected to permit graphic comparison wizh Frisbey"s data (1952). Table 1 presents the design for each of the four groups. For every 30-second period of practice two measures were re- corded for each S —- the total number of hits, and the total time on target. The reading on the cumulative counter at the end of every 30—second work interval was recorded and the number of hits for that trial obtained by sub— traction. A synchronous recording of total time on target was provided by manual operation of the toggle switch every 30 seconds, which simultane- ously stopped one timer and started the other. The time on target to the nearest 0.01 second for the preceding trial was recorded, and the timer was reset to zero while the other timer was being used in the circuit. All data for an S was recorded on an individual data sheet (see Appendix I). The stopwatch was used to measure the 30-second trials and 30- second rest intervals, and the over-all time for the practice and rest sessions. The target surface was cleaned with a fine abrasive paper be- fore each S began the experiment. It was also cleaned, when necessary, during the rest interval to ensure maximal opportunity for circuit completion l6 whenever the stylus was in contact with the target. The calibration of the rotor was checked before each S was tested. The rotor ran continuously throughout each entire experimental session. 4. Procedure. At the beginning of a session S was given the following written in- structions to read. PURSUIT ROTOR EXPERIMENT INSTRUCTIONS The object of this experiment is to see how well you can follow a moving target with a hand stylus. Stand in front of the pursuit rotor with the stylus grasped firmly but in a relaxed manner in your preferred hand. Keep the stylus horizontal and move it around the turning disc with lazy, rotary movements. All the time that the green light is on, you are on the target. I repeat, all the time that the green light is on, you are on the target. Do not begin until I tell you to start, and stop only when I say "stop". Note: Be careful in laying the stylus down, not to hit the green cellophane border around the rotor. The experimenter then repeated the instructions while demonstrating that following was to be done with an easy, relaxed swinging movement, and no extra pressure was to be put on the stylus tip in any way. The stylus handle was to be held lightly with a tennis -type grip; the manner of holding was demonstrated to S. S was given a verbal "ready" signal two seconds before each starting signal, at which point he was told to pick up the stylus l7 and prepare to begin tracking. After the first work period in the distributed practice groups S was informed that he would alternately work and rest. When an S who had for— merly worked under distributed conditions was changed to massed practice following the rest period, he was told that now there would be a period of continuous work. After the first work period in the massed practice groups S was informed that there would be a period of continuous work. When an S was changed from massed to distributed conditions following rest he was told after the first post-rest work period that he would now alternately work and rest. S was instructed to stand quietly in front of the rotor during each 30—second rest interval of the distributed practice condition. During the five-minute rest period S was allowed to sit and converse or read. Any necessary corrections of an S's performance were made with- out interrupting his practice. The principal error noted was in the manner of holding the stylus. An occasional S would tend to slide a finger down the length of the stylus in an attempt to make it rigid; other 88 tended to bend the stylus at the hinge, in order to exert more pressure on the disc, and thus, hopefully, make longer hits. When the stylus was held in this manner S would then be practicing with his wrist bent at a right angle. S was re- minded of the proper method of holding the stylus whenever this error was noted. CHAPTER III RESULTS The foregoing procedure yielded, directly, two measures of rotary pursuit performance per 30-second trial - total time on target and number of hits. Total time on target was converted to a percent-time-on-target score. The number-of-hits score was analyzed directly and was also used in the derivation of the mean hit-duration measure. The latter was computed for each 30-second trial for each S by dividing the total time on target per trial by the number of hits per trial. Three measures were used in the analysis -- percent time on target, number of hits, and mean hit duration. Analysis of variance was used for all statistical comparisons be- tween groups. Comparisons between trials within a group were tested with the 't' test for repeated measures on the same subject (McNemar, 1951). In both types of tests the .05 level of significance was employed. ******* Initial performance: In order to be able to attribute differences in performance to factors of distribution of practice and visual feedback, it is necessary that the groups be comparable initially. Inspection of Figure I shows clearly that, on all three measures of performance, the four groups began at almost identical points. Table 2 presents the means and standard deviations for all four groups for the three measures while Table 3 presents the analyses of variance of the three measures. Since no significant differences between the groups were found on any measure, the conclusion may be drawn that the four groups were performing at an equivalent level initially. ******1‘ 18 L141 J 52: ,6 ms: 5:. 2258 E 32 E: as mmesz I. ll M. I. POST-REST TRIA LS COMPARISON OF THREE RESPONSE MEASURES REST TRIALS PRE- FIGURE I. 19 Table 2 Means and standard deviations for four groups on three measures of the first 30-second period of practice GROUPS. D-D D—M _M_-_1\L M-D PERCENT TIME ON TARGET _ Mean 2.80 V 2.93 2.78 2.70 Standard Deviation 2.51 3.26 2.37 2.39 NUMBER OF HITS Mean 13.50 14.14 15.44 15.28 Standard Deviation 10.51 14.84 13.11 12.72 MEAN HIT DURATION IN SECONDS (x10z ) Mean 5.75 5.96 5.69 4.86 Standard Deviation 3.78 2.21 3.52 2.08 20 Table 3 Analyses of variance between four groups on three measures of the first 30-second period of practice SOURCE OF VARIATION d.f. PERCENT TIME ON TARGET Between groups 3 Within groups 68 NUMBER OF HITS Between groups 3 Within groups 68 MEAN HIT DURATION (x103) Between groups 3 Within groups 68 MEAN SQUARE 2.04 7.08 14.33 166 .07 0.42 0.90 0.228 0.086 0.467 N.S. N.S. N.S. * See Appendix H 21 22 1. Pre -rest distribution of practice. Will the typical superiority in pre ~rest performance of groups working under distributed conditions in contrast to groups working under massed conditions be found for on- target measures as well as for total time on target? In Figure I each performance measure is plotted as a function of practice for the four groups. As inspection of the three families of curves shows, the performance level of groups practicing under distributed con- ditions was markedly higher and increasingly divergent from the level of groups practicing under massed conditions. This difference is noted for two measures - percent time on target and number of hits. For the D groups the greatest increase occurs on the second trial. The hit durations curves are less clearly divergent until the fifth minute of pre -rest practice. The number of hits curve for the distributed groups appears negatively ac- celerated while the percent time on target and hit duration curves do not appear to be levelling off by the end of the six minute work session. All three performance curves for the massed practice groups are flatter though still negatively accelerated. Inspection'of the group means for the last 30-second period of pre- rest practice (Table 4) and the analyses of variance (Table 5) indicates that the groups working under distributed conditions had significantly more time on target and a larger number of hits (p <.05). The on-target measures were clearly sensitive in detecting changes in pre -rest performance due to distribution conditions on the rotary pursuit task. *¢***** Table 4 Means and standard deviations for four groups on three measures of the last 30-second period of pre -rest practice GROUPS D-D D-M __M_—_l\_/I_ M-D PERCENT TIME ON TARGET Mean 15.99 13.58 8.48 5.11 Standard Deviation 8.13 9.31 7.37 4.39 NUMBER OF HITS Mean 43.94 43.33 26.22 21.89 Standard Deviation 17.44 21.41 13.96 12.06 MEAN HIT DURATION IN SECONDS (x103 ) Mean 11.04 8.56 7.98 6.48 Standard Deviation 3.98 5.09 4.72 2.32 23 Table 5 Analyses of variance between four groups on three measures of the last 30-second period of pre-rest practice H MEAN _SOURCE OF VARIATION 3:1: SQUARE _§‘___ p“ ERCENT TIME ON TARGET D groups vs M groups 1 1148.24 20.291 <.01 Pooled residual between” 2 77.44 1.368 N.S. Within groups 68 56.59 NUMBER OF HITS D groups vs M groups 1 6903.13 25.070 <.01 Pooled residual between 2 86. 18 0.313 N.S. Within groups 68 275.35 MEAN HIT DURATION (x103) D groups vs M groups 1 11.88 6.834 <.05 Pooled residual between 2 3.81 2. 119 N.S. Within groups 68 1.74 "‘ See Appendix II 24 25 2. Reminiscence. Will on-target measures as well as the measure of total time on target show more reminiscence present in the massed groups than in the distributed groups after an equal amount of rest, when measured over a 30-second period of practice? Inspection of Figure I shows that two of the three measures, indeed, reflect a gain in performance after rest. The groups practicing under massed conditions before rest clearly made proportionately more hits, and were on target proportionally longer than groups practicing under distributed con- ditions before rest. Reminiscence gain after rest was not conspicuous in the measure of mean hit duration, however. Statistical support for the graphic evidence is presented in Table 6. This table presents the mean reminiscence scores computed separately for each group. Reminiscence was measured as the difference in performance between the first post-rest trial and the last pre -rest trial. Scores for the time on target measure are reported in 0.01 second units, i.e. , scaled by 1x102 , as are scores on the measure of mean duration of hits. Reminis- cence scores for number of hits are reported in unsealed form. From Table 6 it can be seen that, for both time on target and number of hits, mean reminiscence gain is significant at the .01 level for three of the four groups, i.e., D-D, M-M, and D-M, and at the .02 level for the fourth grou -- M-D. On the other hand, only the pre -rest massed groups reach significance on the mean hit duration‘measure. Table 7 presents the analyses of variance of these differences be- tween groups in reminiscence gain. For both time on target and number of hits the differences between massed and distributed groups is highly sig- nificant (p <.01 ) , whereas for mean hit duration the differences between Table 6 Mean reminiscence scores over the five- minute rest period for three measures GROUPS D-D D-M _M;_1\_/L M-D PERCENT TIME ON TARGET Mean 155.39 135.95 238.22 238.34 Standard error 44.18 50.24 38.12 37.35 t 3.52 2.71 6.25 6.38 p <.01 <.02 <.01 <.01 NUMBER OF HITS Mean 7.39 9.94 21.61 24.00 Standard error 1.65 3.53 2.91 2.63 t 4.47 2.82 7.43 9.14 p <.01 <.OZ <.01 <.01 MEAN HIT DURATION Mean 1.54 1.17 2.00 1.41 Standard error 0.79 1.13 0.60 0.64 t 2.01 1.03 3.34 2.21 p N.S. N.S. <.01 <.05 26 Table 7 Analyses of variance between four groups on three measures of reminiscence gain over the five - minute period of rest MEAN SOURCE OF VARIATION d.f. SQUARE F p“ PERCENT TIME-ON TARGET D groups vs M groups 1 154382.72 4.634 <.05 Pooled residual between 2 1701.44 0.052 N.S. Within groups 68 32957.71 NUMBER OF HITS D groups vs M groups 1 3598.35 26.190 <.01 Pooled residual between 2 55.07 0.400 N.S. Within groups 68 137.38 MEAN HIT DURATION (x104) D groups vs M groups 1 2.24 0.186 N.S. Pooled residual between 2 2. 18 0. 181 N.S. Within groups 68 12.03 * See Appendix II 27 28 M and D groups fails to reach significance. The measure of number of hits does reflect changes in performance following rest and does differentiate between massed and distributed groups . Mean hit duration showed reminiscence effects to a much lesser degree. This may be due to the relative insensitivity of this derived index or to the unreliability of gains over rest in average hit durations. It! i t It It: ‘ II: It 3. Initial post-rest trial. Will the difference between spaced and massed con— ditions on the first post-rest trial be significant in the present data for on-target measures as well as for time on target? Table 8 presents the means and standard deviations for the three measures for all groups; the analyses of variance are given in Table 9. For both the time on target and hit duration measures the groups practicing under pre -rest distributed conditions performed at a significantly higher level (p <.05) than did groups practicing under pre -rest massed con- ditions. Since (the groups do not differ significantly in number of hits, the total time on target difference, SIR: can be attributed only to the pre- rest D groups making hits of longer duration. 0! It i It It 3|: t 4. Warm -up. Will both on-target measures as well as total time on target Show a performance increment from the first to the second post-rest trials in groups practicing under unchanged conditions greater than that of graips working under a different temporal schedule following rest? Table Means and standard deviations for four groups on three measures of the first 30-second period of post-rest practice PERCENT TIME ON TARGET M e a n Standard Deviation NUMBER OF HITS Mean Standard Deviation MEAN HIT DURATIONS (x10?- ) M e a n Standard Deviation GROUPS D-D D-M M-M M-D 21.17 18.12 16.42 13.05 9.75 11.41 10.24 7.74 51.33 53.28 47.83 46.44 17.66 22.03 20.74 16.75 12.58 9.72 9.96 7.89 4.94 5.15 4.91 2.98 29 Analyses of Table variance between four groups on three measures of the first 30-second period of post-rest practice SOURCE OF VARIATION PERCENT TIME ON TARGET D groups vs M groups Pooled residual between Within groups NUMBER OF HITS D groups vs M groups Pooled residual between Within groups MEAN HIT DURATION (x102 ) D groups vs M groups Pooled residual between Within groups 68 68 68 d.f. MEAN SQUARE 434.09 92.82 97.47 480.50 25.69 377.04 0.89 0.56 0.21 4.454 0.952 1.274 0.145 4.262 2.679 <.05 N.S. N.S. N.S. <.05 N.S. "' See Appendix II 30 31 Table 10 presents the mean warm -up scores for all three measures. As in the computation of reminiscence the scores for time on target and mean hit duration are reported in 0.01 second units. On the time on target measure the two groups practicing under unchanged post-rest conditions (D-D and M-M) show a significant (p <.01) increment in performance be- tween the first two post-rest trials. For the two groups practicing under changed post-rest conditions (D-M and M-D), the increment between the first two post-rest trials fails to reach significance. The D-D groups showed an increase in both number of hits and mean hit duration measures of warm-up. This finding, while not statistically sig- nificant, suggests that the Significant warm -up increment in percent time on target may be accounted for by Ss making a somewhat greater number of hits of only slightly longer duration. On the other hand, the three remaining groups made _f_6_W§;r hits on the second post-rest trial than on the first, and stayed on target lgilggr. For the D-M group this finding reaches statistical significance (p <.05) on both measures, suggesting that the significant reduction in the frequency of hits was the major factor related to the non-significance of warm -up for the measure of total time on target. Although the duration of hits also increased significantly (p <.01) for both the M-M and M-D groups, the reduction in number of hits was not significant. Moreover, these groups did not differ significantly from the pre-rest distributed groups on hit duration (Table 11). Analyses of variance (Table 11) were used to evaluate whether or not the mean warm-up increments in the unchanged groups are significantly greater than the increments in the changed groups. Since this is a prediction of an interaction effect, the residual mean square consists of the pooled pre- and post-rest conditions effects. This interaction was found to be non- Table 10 Mean warm -up scores derived from the first two trials of post-rest practice for three measures PERCENT TIME ON TARGET (x103 ) Adean Standard error I: P 1WfiMBERp>.05) that there is a general trend toward a relative depression of performance as a function of a change in the stimulus situation. ' It: at: It: at: It: at: at: 5. Post-rest practice period. Will the number of hits stabilize or decrease while dura- tion of hits increases, during the post-rest practice period, at least for the distributed practice condition? While the total time on target scores (Figure I) for the D-D group after the first post-rest trial showed only very slight improvement in per- formance until the last trial of post-rest practice, the anticipated changes in the performance of the D-D group occurred throughout the post-rest practice session. The mean number of hits at first stabilized and then, after trial 6, decreased to a slightly lower level and stabilized again. At the same time there was an increase in the duration of hits. The M-D group showed a relatively stable number of hits until the seventh trial, accompanied by steadily increasing hit durations. Then hit durations continued a step-wise rise, while hit frequency scores followed a trough-like pattern. The number of hits for the D-M group declined steadily throughout the post-rest session while hit durations improved slightly until trial 6. During the last half of post-rest practice, however, hit durations were much shorter. The M-M group showed the proposed relationship of increasing durations, and decreasing,stabilizing hit frequency scores, until trial 8. 35 Thereafter hits declined slightly, while durations dropped to a lower stable level. * * t * * t O 6. Convergence. Will groups practicing under like conditions, after the variable of distribution of practice has had a chance to operate in post-rest performance, converge and remain together so that at the end of the post-rest period distribu- ted groups (D-D, M-D) will be superior to massed groups (M-M, D—M) on the total time on target measure? and 7. Convergence in on-target measures. Will both duration of hits and number of hits measures converge by the end of the post-rest practice session for groups practicing under like conditions? As can be seen from Figure I convergence between post-rest D groups and between post-rest M groups clearly occurred for both the time on target measure and the number of hits measure. The convergence was complete and overlapping for the number of hits measure in both con- ditions by trial 9. The D-M group performance was regularly lower than the M-M group for percent time on target after the first 30 seconds of work. Convergence may also be seen for the duration of hits measure. The M-D group scores steadily approached, but did not overlap, the level of the D-D group. Hit durations for the D-M group were markedly less than for the M-M group at every point after the first post-rest trial. Table 12 sets forth the means and standard deviations for the four groups on all three measures of the last post-rest trial performance; Table 12 Means and standard deviations for four groups on three measures of the last 30-second period of post-rest practice GROUPS D-D D-M _l\£-_l\_/l_ M-D PE RCENT TIME ON TARGET Mean 26.29 13.72 15.35 25.26 Standard Deviation 10.53 8.78 9.00 13.83 NUMBER OF HITS Mean 51.17 37.56 38.94 48.72 Standard Deviation 16.47 13.19 17.09 12.37 MEAN HIT DURATION IN SECONDS (x102 ) Mean 16.96 9.78 11.82 14.06 Standard Deviation 8.89 4.50 5.49 6.33 36 Table 13 Analyses of variance between four groups on three measures of the last 30-second period of post-rest practice MEAN SOURCE OF VARIATION fl SQUARE F p“ PERCENT TIME ON TARGET D groups vs M groups 1 2273.51 19.761 <.01 Pooled residual between 2 16.86 0. 147 N.S. Within groups 68 115.05 NUMBER OF HITS D groups vs M groups 1 2461.68 11.061 <.01 Pooled residual between 2 31.07 0. 140 N.S. Within groups 68 222.55 MEAN HIT DURATION (x103) D groups vs M groups 1 39.90 9.409 <.01 Pooled residual between 2 5.66 1.333 N.S. Within groups 68 4.24 * See Appendix II 37 38 analyses of variance of the differences between the means are presented in Table 13. The spread between post-rest D and M conditions is sig- nificant (p <.01) for all three measures. The residual (groups treated alike) which includes the variance associated with the comparison of: (1) pre-rest groups treated alike, and (2) interaction, is clearly non-sig— nificant. On the basis of this statistical analysis the conclusions safely may be drawn that convergence has occurred at the last post-rest trial on all three measures, and that the divergence between D and M groups is a function of post-rest conditions. an: an: a: s I: a: s 8. Visual feedback. Will a visual feedback cue occuring simultaneously with each stylus -target contact have a facilitating or decremental effect on rotary pursuit performance? Figures 11 and III present a comparison between the data of the present study and a graphic presentation of the Frisbey (1952) data. For each study the graphs Show the average of the group means for each con- dition before rest (i.e., D = (D-D + D-M)/2; M = (M-M + M-D)/2). For the post-rest period Figure 11 presents a comparison of the four pre-rest distributed groups, while Figure III presents a comparison of the four pre-rest massed groups. The groups in the two studies were similar and overlapping at the beginning of practice. But, after two minutes of practice in the pre -rest period performance of the groups in the present study was consistently poorer than that in the Frisbey study. The average increments in total time on target were almost twice as great for the Frisbey groups. The difference between the massed groups was much less marked. ,o , n“ ,‘ _ 3 .3 i‘ 2 "4 n o 0 _" i 'E 0 0 K n. x a: .40 o o ‘ ‘\ a '2 2“: e E? e} \ , , ~~ \ I . l . I I t t \ A I "" ‘ \ ) «a I k -A \ A fit \ \ .1 \ \ .74 \\ ‘0 --- \ «0" 1 l 1 1 1 1 L a .2 a .2. 2 2 M ° PERCENT TIME ON TARGET F I G U R E II COMPARISON BETWEEN THE FRISBEY (1952)/UNI) K(_)(")NS DATA FOR POST - REST DISTRIBUTED CONDITIONS 39 REST TRIALS POST REST TRIALS PRE 3‘: Vs w a a 3 E —" C C o o ‘ Usur Kiri g ‘E E ii 0 Q its: re 52 a} .. A 1 '1‘” —l~l —