ADAPTED PHYSICAL ACTIVITY QUARTERLY, 1991,8,342-356 Effects of Variability of Practice on the Transfer and Performance of Open and Closed Motor Skiills Thomas A. Eidson University of Akron Robert E. Stadulis Kent State University Schmidt's (1975) schema theory hypothesis of variability of practice on the performance of both a closed and an open motor skill was investigated. Following an acquisition phase for each task, moderately mentally handi- capped (MH) and nonhandicapped (NH) subjects were randomly assigned to either variable or constant practice. For the closed skill, constant practice groups exhibited more absolute error than the variable practice groups during performance of a transfer task. No significant effect of type of practice for the open skill was obtained. For the open skill, MH subjects had significantly greater absolute error and variable error than NH subjects; no performance differences were evidenced for the closed skill. For both MH and NH sub- jects, Schmidt's variability-of-practice hypothesis was supported, but only for closed skills. The study of children's motor skill performance, both handicapped and nonhandicapped, has been investigated in many ways. The purpose of the present study was to examine two major motor learning variables: (a) the type of motor skill being practiced and (b) the method of practice being used, with reference to differences in the learner's cognitive capabilities. If the type of skill and1 or practice interact with the cognitive capabilities of the learner, then different instructional strategies may be needed depending on the capabilities of the learner. The type of motor skill being performed has been suggested as an important variable to consider in the learninglinstruction process. In particular, Gentile (1972) has asserted that skills classified as open or closed should be practiced differently. An open skill, according to Poulton (1957), is one that has an unpre- dictable set of environmental requirements, for example hitting a thrown base- ball. A closed skill, on the other hand, is one that can be performed without a direct response to environmental aspects, for example the shot put. Gentile, Higgins, Miller, and Rosen (1975) extended the openlclosed model and developed a taxonomy of motor skills based upon environmental re- quirements (stablelstationary vs. unstablelmoving) and movement requirements (total body stability, i.e., sitting or standing vs. total body transport, i.e., walking rints from Th~mas~A. Eidson, Memorial Hall, DepaTtment of H ion, The University of Akron, Akron, OH 44325-5103.
Effects of Variability of Practice on the Transfer and Performance of Open and Closed Motor Skiills
Thomas A. Eidson University of Akron
Robert E. Stadulis Kent State University
Schmidt's (1975) schema theory hypothesis of variability of practice on the performance of both a closed and an open motor skill was investigated. Following an acquisition phase for each task, moderately mentally handi- capped (MH) and nonhandicapped (NH) subjects were randomly assigned to either variable or constant practice. For the closed skill, constant practice groups exhibited more absolute error than the variable practice groups during performance of a transfer task. No significant effect of type of practice for the open skill was obtained. For the open skill, MH subjects had significantly greater absolute error and variable error than NH subjects; no performance differences were evidenced for the closed skill. For both MH and NH sub- jects, Schmidt's variability-of-practice hypothesis was supported, but only for closed skills.
The study of children's motor skill performance, both handicapped and nonhandicapped, has been investigated in many ways. The purpose of the present study was to examine two major motor learning variables: (a) the type of motor skill being practiced and (b) the method of practice being used, with reference to differences in the learner's cognitive capabilities. If the type of skill and1 or practice interact with the cognitive capabilities of the learner, then different instructional strategies may be needed depending on the capabilities of the learner.
The type of motor skill being performed has been suggested as an important variable to consider in the learninglinstruction process. In particular, Gentile (1972) has asserted that skills classified as open or closed should be practiced differently. An open skill, according to Poulton (1957), is one that has an unpre- dictable set of environmental requirements, for example hitting a thrown base- ball. A closed skill, on the other hand, is one that can be performed without a direct response to environmental aspects, for example the shot put.
Gentile, Higgins, Miller, and Rosen (1975) extended the openlclosed model and developed a taxonomy of motor skills based upon environmental re- quirements (stablelstationary vs. unstablelmoving) and movement requirements (total body stability, i.e., sitting or standing vs. total body transport, i.e., walking
rints from Th~mas~A. Eidson, Memorial Hall, DepaTtment of H ion, The University of Akron, Akron, OH 44325-5103.
Effects of Variability of Practice 343
or running). Building upon Gentile et al.'s taxonomy, Hoffman, Imwold, and Koller (1983) varied both the environmental and the movement response require- ments. Subjects performed under four conditions: Type 1-both the body and the environment stable; Type 2-body stable, environment unstable; Type 3-body unstable, environment stable; and Type 4-body unstable, environment unstable. Results were interpreted to suggest that Type 1 and 3 tasks represented closed skills while Type 2 and 4 tasks could be categorized as open skills.
Whether the type of motor skill to be learned influences the procedures undertaken to promote such learning has been a debated issue. In particular, many researchers have examined whether the method of practice influences mo- tor skill acquisition and performance. For example, Schmidt's (1975) schema theory argues for a variable practice schedule, for example changing environ- mental and movement response demands, regardless of the type of task being ~erformed.
Numerous investigators have examined Schmidt's variability-of-practice notion and have demonstrated varying degrees of support for the concept (e.g., Moxley, 1979; Porretta, 1982; Wrisberg, Winter, & Kuhlman, 1987). Tasks used have included throwing bean bags, kicking a ball, and arm movement to a target, respectively. More recent examination of variability of practice in con- junction with contextual interference theory (Turnbull & Dickinson, 1986) some- times evidences support for variable over constant practice (Schmidt, 199 1) , but not always (Wrisberg & Mead, 1981, 1983). Shea and Kohl (1990) have even provided evidence that practicing variations of a criterion task is better for reten- iion than constant of the specific criterion.
Whereas schema theory argues for variability of practice for all tasks, Gentile's (1972) model stipulates that closed skills require consistency andlor fixation of movement, and thus a constant practice schedule. On the other hand, for an open skill the performer needs to emphasize variability andlor diversifica- tion of movement, thus warranting a variable practice schedule.
Although not receiving as much research attention as Schmidt's theory, Gentile's model has some investigation (Cooper & Rothstein, l 9 a ; Del Rey, 197 1; McBride & Rothstein, 1979). However, these studies have varied the type of feedback provided rather than the practice procedure, and any attempt to test Gentile's suggestion that information about the movement execu- tion-knowledge of performance (KP)-would be more appropriate for closed skills whereas information about the movement's outcome-knowledge of results (KR)-should receive greater emphasis within open skills.
In addition to the type of motor skill and type of practice variables, the learner's level of functioning in performing the skill affects our understanding of motor skill learning and performance. Researchers have examined the effects of the mentally handicapped individual's limited cognitive capabilities on various motor abilities, for example reaction time and movement time (Hoover, Wade, & Newell, 198 I), timing performance (Nettlebeck & Brewer, 198 I), pursuit tracking (Kerr & Blais, 1985, 1987), and coincidence anticipation performance (Durnrner, 197811979; Edwards, Elliott, & Lee, 1986; Wade, Newell, & Hoo- ver, 1982; Wrisberg, Martin, &Wren, 1983). Much of this research has focused on those with mild levels of mental retardation.
Timing tasks may provide an opportunity to manipulate the openlclosed nature of the motor task studied. The basic issue of practice variability versus
344 Eidson and Stadulis
practice constancy and the hypothetical relationship to the type of task can be examined. Most especially, there appears to be a need to investigate the type of practiceltype of task relationship within the context of the learner's cognitive capabilities.
Recommending variable and diversified practice, as done by Gentile for open skills and Schmidt for all motor skills, seems in opposition to the often recommended practice procedure of redundancy (fixation) when pedagogical guidelines are given to the teacher of the mentally retarded individual (Arnheim & Sinclair, 1985).
One particular aspect of research with respect to the type of skill variable needs to be noted. Some investigations (Del Rey & Stewart, 1989; Wrisberg & Mead, 1981,1983) have claimed that they tested subjects on an open motor skill when using a coincident timing task in which the speed of the stimulus display remains the same from trial to trial during the transfer phase. However, such an unchanging display would seem to better fit Poulton's (1957) "closed skill with predictable requirements." At best, such a task could be classified as "open with advanced information" (Poulton, 1957, p. 474).
In the present study, unlike previous efforts, the transfer phase employed a task in which the display speed from trial to trial was not predictable or antici- pated through advanced information. Thus the present study tried to examine a motor skill with task requirements more toward the open end of the skill continuum.
Therefore the present investigation sought to examine the effects of vari- ability of practice on the performance of open and closed motor skills. Perfor- mance of novel instances of the previously practiced motor tasks was measured for both moderate mentally handicapped and nonhandicapped individuals. Of particular interest was Schmidt's (1975) variability-of-practice hypothesis and its impact on the moderately mentally handicapped individuals' performance; that is, would limited cognitive processing ability adversely affect performance under variable practice versus constant practice conditions?
Most previous studies have used only mildly retarded subjects (IQ = 50-70). Schmidt (1991) proposes that variable practice aids the formation of the schema, or a set of rules, which the learner acquires that generalizes to all in- stances of a class of actions. Variable practice involves practicing several tasks of a class of tasks, which should result in greater generalization. Porretta (1982) and Kanode and Payne (1989) report findings that suggest that persons with more limited cognitive processing capabilities (mild mental retardation) are at least not hindered by variable practice. Would more moderately retarded individuals be more adversely affected by variable practice? Further, both earlier studies used closed skills.
Perhaps examining open skill learning and performance might be more sensitive, either positively or negatively, to variable practice. Therefore a second focus of the study was to examine motor task performance in terms of environ- mental demands. Specifically, the hypothesis tested was that performance differ- ences between moderate mentally handicapped and nonhandicapped subjects would be greater in the open task situation (greater environmental demands) than in the closed task situation (less environmental demands).
Effects of Variability of Practice 345
Method
In order to test the hypothesis, the present study consisted of two experiments focusing on tasks that represented different environmental demands in per- forming the same movement. Experiment 1 evaluated subjects' performance on a closed motor task while Experiment 2 evaluated performance on an open motor task. The same subjects participated in both experiments.
Subjects
The subjects were 24 moderately mentally handicapped (MH) individuals (M chronological age = 19.0 yrs, range = 15.8 to 22.6 yrs; M mental age = 6.4 yrs, range = 5.1 to 7.1 yrs) enrolled in a County Board of Mental Retardation program, and 24 nonhandicapped (NH) individuals (M chronological age = 10.9 yrs, range = 9.7 to 12.9 yrs) enrolled in a local public school. The classification of MH subjects as moderate was made by the county board.
Subjects were not matched for chronological age because of the possible greater disparity in performance of the two groups; that is, the NH experiential background would be far superior to that of the MH subjects. Matching subjects for mental age was considered as well. However, for the open task, previous results using a similar (Stadulis, 1971) or the same (Stadulis, 1985) display with a less complex movement response would predict that the NH subjects would have been too young to adequately perform the task; that is, many trials would result in either nonresponse or delayed responses so late as to suggest no attempt to time the response to the display. Therefore the NH group consisted of subjects who were young, yet able to perform the task, while the MH group consisted of subjects who were able to comprehend and perform the task. Pilot study con- firmed both potential samples as able to comprehend the task.
Experiment 1, Closed Skill
Apparatus
The apparatus used in Experiment 1 was a linear slide apparatus. It consisted of two 1.27-cm stainless steel rods (91.44 cm long) mounted horizontally, and parallel to each other, on a wooden base. Two microswitches were mounted to an aluminum track and located 24 cm from each other. The task for each subject throughout Experiment 1 was to move the slide from the first through the second microswitch at a specified movement time (MT). The subject's actual MT was recorded in milliseconds (ms) displayed on a clock (Lafayette Model 50575).
Procedure
Experiment 1 consisted of three phases: an acquisition phase, a practice phase, and a transfer phase. The purpose of the acquisition phase was for the subject to get the idea of the movement (Gentile, 1972) before beginning the practice phase. Subjects were instructed to move the slide from the first microswitch "through" the second microswitch so that the MT equaled 300 ms. The choice of this criterion (300 ms) was based on pilot study; that is, the MH subjects' mean MT
346 Eidson and Stadulis
was approximately 300 ms when asked to perform the task without any time constraints imposed. (See Eidson, 1985, for additional information concerning pilot study procedures and results.)
The acquisition phase consisted of a minimum of 12 trials. To continue to the next phase, subjects had to perform three out of four consecutive trials within L- 100 ms of the 300 ms. All subjects achieved this criterion.
Feedback was given during the acquisition phase and was in the form of verbal qualitative information such as "too slow" or "too fast." Augmented visual feedback was provided as well. Constructed for the MH subjects espe- cially, the visual feedback consisted of a number line with the criterion speed (300 ms) located in the middle and the end points represented as "too slow" and "too fast." A movable cursor was used to indicate how and where each subject responded in relation to the criterion speed.
During the practice phase, subjects from both groups were randomly as- signed to one of two treatment conditions: variable MT practice or constant MT practice. The variable MT practice group attempted to move at MTs of 250, 300, and 350 ms. Again, pilot investigation suggested that these were within the subjects' capabilities, with 200 ms appearing to be the lower limit to perfor- mance. Over the 18 trials in the practice phase, each MT was presented six times in random order; no MT could occur more than twice in succession. The constant MT practice group attempted to move so that their MT equaled 300 ms on all 18 trials. Feedback was continually being provided in the practice phase.
Following the practice phase, subjects from both practice groups began the transfer phase, which consisted of 12 trials at two novel MTs (275 or 325 ms). The choice of these novel MTs was again determined by pilot study, that is, within the subject's capabilities, perceived differently (different mean MTs re- sulting), equidistant from the practice phase speeds, and within the practice MTs range. The two MTs were randomly presented and six trials of each were admin- istered. No KR was provided.
Data Analysis Three error scores were determined. Absolute error (AE) was the difference between the MT produced by the subject and the criterion MT. Variable error (VE) was the standard deviation of the signed error scores within a block of six trials at any of the three phases. Constant error (CE) was the difference between the subject's MT and the criterion MT, where a faster than criterion MT was signed negative and a slower MT signed positive. For presentation purposes, only descriptive CE findings will be shared.'
Mixed-design ANOVAs were computed at each phase, with the specific factors changing being somewhat dependent upon the phase examined. The ac- quisition phase employed a 2 x 2 x 2 (MH or NH X Gender x Trial Blocks) design, with repeated measures on the last factor. For the practice phase, the 2 X 2 X 3 mixed ANOVA represented subjects (MH or NH), type of practice (variable or constant), and blocks, respectively.
In the transfer phase, a four-factor design was employed; in addition to subjects, type of practice, and blocks, the data from the last two blocks of the acquisition phase were included as a second repeated-measures factor, to assess change from baseline. Simple main-effect analyses were used to interpret signifi- cant interactions, p< .05.
Effects of Variability of Practice
Table 1
Mean and Standard Deviation AE, VE, and CE for Handicapping Condition Over Blocks During the Acquisition Phase of the Closed Skill
Block 1 Block 2
Handicap condition n M SD M SD
AE MH NH Overall
VE MH NH Overall
CE MH NH Overall
Results
During the acquisition phase, the AE and VE ANOVAs revealed no main effects for handicapping condition: AE, F(1,44) = 3.70, p = .06; VE, F(1,44) = 2.69, p = . l l ; orforgender: AE, F(1,44) = .95,p=.34; VE, F(1,44) = 1.52,p=.22. However, main effects were evidenced for both absolute and variable error for blocks: AE, F(1,44) = 4.77, p = .03; VE, F(1,44) = 4.41, p= .04. Subjects exhibited greater AE and VE during Block 1 than in Block 2, that is, their performance improved during the acquisition phase (see Table 1). All interaction effects for both error scores were not significant (p>.05). CE scores indicated that on the average both MH and NH subjects moved somewhat slower than the criterion MT.
Practice phase analysis indicated that the MH subjects performed with significantly greater AE than did the NH subjects, F(1,44) = 4.05, p = .05. Differences in VE due to handicapping condition were nonsignificant. In addi- tion, practice condition (variable vs. constant) results indicated no significant differences in performance during the practice phase. Table 2 summarizes the descriptive statistics for the practice phase.
Analysis of the transfer phase resulted in a significant main effect for type of practice, F(1,40) = 4.82, p= .03, for AE scores, with the constant practice groups exhibiting more AE than the variable practice groups. As illustrated in Figure 1, variable practice resulted in better performance (less error) for both the MH and NH groups, F(1,40) = 3.54, p= .07. In addition, the MH variable practice group exhibited (descriptive only) less AE and VE than the NH constant
Table 2
Mean and Standard Deviation AE, VE, and CE for Handicapping Condition, Type of Practice, and Blocks During the Practice Phase for the Closed Motor Skill
Block 1 Block 2 Block 3 Block 4
Handicap condition Type of practice n M SD M SD M SD M SD
Figure 1 - Mean group absolute and variable error over phases for the closed skill. Mentally handicapped U; Nonhandicapped 0; Constant practice - ; Variable practice - - - .
practice group during the transfer phase for the closed skill. A likely reason for the presence of nonsignificance here, or within other analyses, comes from the large standard deviations evidenced by the MH subject^.^
Discussion
The closed skill results did not support previous research (e.g., Wrisberg et al., 1983), in that the nonhandicapped subjects did not perform better than the men- tally handicapped subjects. When presented with a timing task of relative simple environmental complexity, a temporal constraint only, the moderately mentally handicapped subjects were able to perform as well, and in some cases better, than the nonhandicapped individuals (see Figure 1). Schmidt's (1975) variability- of-practice hypothesis thus received strong support when the performance of a closed skill transfer task was examined.
Variable practice was better than constant practice when transferring to novel movement times. Not only was it better for both subject groups, but the mentally handicapped variable practice group performed (descriptive only) with less absolute and variable error at transfer than did the nonhandicapped constant practice group. These fmdings support previous research on variability of prac- tice and the mentally handicapped (Edwards et al., 1986; Porretta, 1982).
The second experiment, using a more open skill as the task, was undertaken to determine whether the presence of greater environmental demands affected
350 Eidson and Stadulis
findings obtained for the closed skill. In particular, since both Schmidt (1975) and Gentile (1972) offer support for variableldiversified practice, it was hypothe- sized that variable practice would be superior. The key question here was whether the moderately MH subjects would benefit from variable practice as they had in Experiment 1 with the closed skill. Or would the increased task complexity and environmental demands render variable practice too demanding and confusing to be useful to them?
Experiment 2, Open Skill Apparatus The apparatus used in Experiment 2 was the linear slide apparatus, as described in Experiment 1, interfaced with a Bassin Anticipation Timer (Lafayette Model 50575). The subject was seated perpendicular to the linear slide apparatus and the Bassin runway with the second microswitch and the last light of the runway positioned at the subject's midline (spatially simulating a basebaWsoftball batting task). The task was to move the linear slide handle from the first to the second microswitch, con- tacting the second microswitch as, or coincident with, the illumination of the last light on the Bassin runway. The runway consisted of start and finish modules with two intermediate runway models (total distance of LED display = 286.4 cm).
Procedure Experiment 2 consisted of three phases, as described in Experiment 1. During the acquisition phase, subjects practiced at 134 cmls, with the criterion for subse- quently beginning the practice phase being three out of four consecutive trials in which absolute error was <I00 ms. Again, qualitative feedback (too early or late) and visual information feedback, as described in Experiment 1, was given in the acquisition and practice phases only.
During the practice phase, half of the subjects in the NH and MH groups were randomly assigned to one of two treatment conditions: a variable-stimulus- display speed practice group (44, 134, 224 cmls) or a constant-stimulus-display speed practice group (134 cmls). As in Experiment 1, selection of display speeds was based on a number of factors such as performance capabilities demonstrated during pilot study, equidistant speed differences, and so forth. The viewing time for each speed, from initial LED illumination to the last light, was 6.5 (44 c d s ) , 2.1 (134 cmls), and 1.3 (224 c d s ) seconds. Over the 18 trials in the practice phase, the variable practice group experienced six trials of each stimulus display speed in random order; no stimulus display speed could occur more than twice in succession.
Following the practice phase, subjects entered the transfer phase and per- formed 12 trials in which the task was to coincide the movement of the linear slide to novel stimulus display speeds of 89 and 179 cmls. Viewing time was 3.2 and 1.6 seconds, respectively; the presentation of speeds was randomized.
Data Analysis Three error scores, AE, VE, and CE, were again computed. The difference in ms from when the subject contacted the second linear slide switch to the time the last light on the runway illuminated constituted AE. For CE, early responses were signed negative while late responses were signed positive. AU inferential analyses conducted for the closed skill were applied to the open skill error scores.
Effects of Variability of Practice 351
Results
For the open task, the MH subjects had greater difficulty in reaching the criterion level of performance during the acquisition phase than they had for the closed task. Elevenof the 24 MH subjects did not reach criterion, and those MH subjects who did reach criterion took significantly more trials, F(1,44) = 23.56, p<.01, than the NH subjects (M, = 19.1 ; M, = 13.5). Main effects for handicapping condition were found for both absolute and variable error, with the MH exhib- iting significantly greater AE, F(1,44) = 17.26, p<.01; and VE, F(1,44) = 26.67, p<.01, respectively.
Practice phase results indicated significant effects for both handicapping condition and practice for absolute as well as variable error. The constant practice group exhibited less AE, F(1,33) = 5.14, p=.03; and VE, F(1,33) = 12.88, p<.01, than did the variable practice group. Regardless of practice condition, the NI-I subjects evidenced significantly less AE, F(1,33) = 14.41, p<.01, than did the MH subjects. A summary of descriptive statistics for the practice phase is provided in Table 3. For CE, both MH and NH subjects tended to be early with their responses. This also suggests that the fastest display speed (224 crnls) was not too fast for responsive performance by subjects.
Analysis of transfer phases AE and VE indicated that the NH performed with less error than did the MH subjects: for AE, F(1,29) = 63.21, p<.01; for VE, F(1,29) = 41.48, p<.01. All interactions were nonsignificant except for type of subject and blocks (for both AE and VE). Simple effect and Tukey HSD analyses indicated that, for both AE and VE at Block 2, NH subjects had less error than MH subjects. At Block 1 the NH subjects evidenced less AE (M = 92.3 ms) than their MH counterparts (M = 272.9 ms). For MH subjects only, significantly less VE occurred at Block 2 (199.7 ms) than at Block 1 (390.3 ms).
The effect of constant versus variable practice was not strong: AE, F(1,29) <0.01, p = .95; VE, F(1,29) = 0.04, p= .85. While not significant, as Figure 2 illustrates, variable practice resulted in better performance, that is, less AE and VE error, for the NH subjects while constant practice was best for the MH subjects
Discussion
The open skill results concur with previous research (e.g., Wade et al., 1982) relative to handicapping condition. The mentally handicapped had difficulty when presented with a highly complex coincident timing task that was both tem- porally and spatially constrained. Almost half (46%) of the MH subjects did not reach the criterion level of performance during acquisition. These results would seem to support the often suggested notion of a simple to complex principle of teaching the mentally handicapped (e.g., Wiseman, 1982). The open skill task was apparently too complex; the identical motor task that the MH subjects were able to do quite well in a closed setting (Experiment 1) was much more difficult to accomplish when the moving display was added.
Unlike the closed skill, support for variable practice occurred only for the NH subjects. For the moderately mentally handicapped subjects, constant prac- tice seemed superior. However, these differences concerning the variable versus constant practice comparison were only descriptive; inferential analysis did not yield significance for the differences observed.
Table 3
Mean and Standard Deviation AE, VE, and CE for Handicapping Condition, Type of Practice, and Blocks During the Practice Phase for the Open Motor Skill
Block 1 Block 2 Block 3 Block 4
Handicap condition Type of practice n M SD M SD M SD M SD
s 71.3 o, Constant 12 -28.4 39.1 -23.8 24.0 0.6 49.3 -17.2 37.1 S Overall 24 -35.8 61.2 -32.3 48.3 -1.1 48.3 -23.0 61.1 $
Effects of Variability of Practice
I , I t I I I #
Acq. Pract ice Trans Acq. Pract ice Trans.
Phases
Figure 2 - Mean group absolute and variable error over phases for the open skill. Mentally handicapped 0; Nonhandicapped 0; Constant practice - ; Variable practice --- .
General Discussion
In three of four of the experimental combinations-NH closed skill, NH open skill, and MH closed skill-variability of practice was superior to constant prac- tice, although not always significantly so, when novel parameters were intro- duced during the transfer phase. Unlike Doody and Zelaznik (1988), who questioned the validity of schema theory when using a linear slide timing task similar to that used in the present study, schema theory and the benefit of variable practice were supported in this investigation.
One reason for disparity in findings between studies may stem from the subjects studied. The present investigation found variable practice effective for children and moderately mentally handicapped individuals. Doody and Zelaznik, using typical college-age students, found variable practice to be less effective than constant practice. Perhaps the greater motor task experiences of these sub- jects of college age mediated the novelty of the transfer task, making it more reflective of performance rather than learning factors. Doody and Zelaznik in fact question whether schema theory is a learning theory at all; rather, they suggest it might be better characterized as a performance theory.
Based on our results as well as those of others (Edwards et al., 1986; Porretta, 1982), schema theory seems quite useful as a learning theory when the
354 Eidson and Stadulis
task is a closed motor skill and the learners are children andor moderately to mildly mentally handicapped persons.
Previous studies using mildly mentally retarded children (Del Rey & Stew- art, 1989) and first-graders (Wrisberg & Mead, 1981,1983) did not find a varied- random practice procedure better than constant practice in the performance of a coincidence/anticipation transfer task. This matches the present study's findings with respect to the moderately MH subjects. It appears that variable practice, in a randomized fashion, may be limited by cognitive level of function (mildly and moderately retarded persons) or developmental level. For instance, Wrisberg and Mead's first-graders were not aided by variable-random practice whereas the present study's older children, fifth-graders, were. However, variable prac- tice seems recommended for open skills for learners who have reached an appar- ent threshold level of development.
From a pedagogical perspective, the results of the present investigation warrant further consideration. In dealing with the relative short attention span of MH individuals, textbooks in adapted physical education (Auxter & Pyfer, 1985) have suggested an emphasis on variety when teaching motor activities. However, specific suggestions as to how to practice these tasks usually are not included. Some who do address the practice schedule variable have suggested that "many retarded children learn best by drill and repetition" (Arnheim & Sinclair, 1985, p. 209).
The findings of the present investigation suggest that such a generalized practice recommendation may be incorrect. Teachers of mentally handicapped students need to consider the type of skill to be learned together with the type of practice to be followed. For a task with relatively simple environmental demands, for example a closed skill, the mentally handicapped may in fact benefit from variable practice within the range of task parameters rather than from drill and repetition. On the other hand, for a task with more complex environmental de- mands such as an open skill, the findings of this study suggest that constant or repetitive practice may be best for moderately mentally handicapped individuals. However, more real-life tasks and activities need to be examined with variable practice before such guidelines would be generalizable.
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' As noted by Schutz and Roy (1973), when AE, CE, and VE are computed, data analyses should be restricted to only two of the scores. While VE and CE are preferred, the especially large standard deviations for CE render inferential analysis inappropriate. In any case, any one of the three error scores can be predicted from the other two.
An anonymous reviewer wondered if the MH could differentiate MTs within a range of only 100 ms. The editor suggested that more accurate performance during the transfer phase, especially for the MH subjects, might have been the result of continuing to produce the 300-ms acquisition MT despite being asked to produce 275 or 325 ms movements. However, calculations of mean MTs and 275 and 325 ms did indicate differ- ential responses by the MH subjects.
Author Mote
Research reported in this manuscript was conducted as part of the doctoral disserta- tion submitted by Thomas A. Eidson to Kent State University under the direction of Phillip L. Safford and Robert E. Stadulis.
