JOURNAL OFSPORT PSYCHOLOGY, 1982,4,41-51

Efficacy of Mental Imagery in Enhancing Mental Rehearsal of Motor Skills

E. Dean Ryan and Jeff Simons University of California

To investigate the mental imagery aspect of mental rehearsal, 80 male traffic of- ficers from the California Highway Patrol learned a novel balancing task during a single session. Based on a pretest questionnaire, subjects were categorized as imagers, nonimagers, or occasional imagers and assigned to one of six groups accordingly: imagers asked to use imagery in mental rehearsal, imagers asked to try not to use imagery, nonimagers asked not to use imagery, nonimagers asked to try to use imagery, physical practice, or no practice. It was hypothesized that a person's preferred cognitive style would prove most effective for use in mental rehearsal and that using another style would cause a decrement in learning. Im- provement scores indicated no differences between subjects who initially reported typically using imagery and those reported typically not using it, but groups asked to use imagery in mental rehearsal were superior to those asked not to (pc.001). Overall, physical practice was better than the grouped mental rehear- sal conditions, and both were better than no practice. Subjects reporting strong visual imagery were superior to those with weak visual images @<.03), and those reporting strong kinesthetic imagery were superior to those with weak kinesthetic images (pc.03). Regardless of one's typical cognitive style, the use of vivid im- agery appears quite important for enhancement of motor performance through mental rehearsal.

There has been considerable anecdotal evidence that mental imagery is effective in improving performance of athletic skills. Possibly the earliest published reports were by Morrison (1932, 1940), who proposed a rather elaborate system of mental rehear- sal for golfers to improve their game during the winter. More recently, Jack Nicklaus, in a syndicated column (1976) stated, "I go to the movies in my head .... First I 'see' the ball where I want it to finish ... next I see the ball going there ... finally I see myself making the kind of swing that will turn the first two im- ages into reality." The mental approach has not been limited to golf. Bill Russell and Branch in basketball (1979), Dick Fosbury in track (1974), Tim Gallwey in tennis (1974) and skiing (1977), and many others have attested to the efficacy of imagery in enhancing athletic performance. Although there have been many con- trolled studies of the influence of mental rehearsal on motor skills, very few have specifically studied the imagery aspect that seems to be so important in anecdotal reports by athletes. Results from those studies that have been completed are equivocal. Clark (1960) emphasized the use of imagery in a study that found mental practice "almost as effective as physical practice" in improving basketball free

Requests for reprints should be sent t o E. Dean Ryan, Department of Physical Education, University of California, Davis, CA 95616.

42 RYAN AND SIMONS

throwing. Marks (1977) reported a study examining the efficacy of mental imagery in learning a modified pursuit rotor. Vivid imagers, as measured by a questionnaire (Marks, 1973), showed greater reminiscence effects than poor imagers. Marks con- cluded, "The study confirms the role of individual differences in imagery vividness in the mental practice of physically demanding psychomotor skills" (p. 287). On the other hand, Start and Richardson (1964) found no relation between either vividness or controllability of imagery in learning and performing a gymnastic skill, although there was a suggestion that vivid imagers who had high control of the imagery per- formed better than all other imagery combinations. A recent study by Epstein (1980) found no differences in dart throwing between persons using imagery and a relaxa- tion control group.,

It may well be that even in studies showing enhancement of physical performance through mental rehearsal, mental imagery itself is unnecessary. Mental rehearsal without imagery may be just as effective in improving motor skills as with vivid im- agery. Because people differ in the amount and quality of their imagery, it seems reasonable that mental rehearsal using one's natural cognitive mode may be most beneficial. Thus, those who rarely or never use mental imagery may mentally rehearse best without it, whereas those who often use imagery may attain best results by using it in mental rehearsal.

It is predicted that an individual's preferred cognitive style should be the most ef- fective for their mental rehearsal and that forced use of another style will impair learning. In addition, those individuals whose usual mode utilizes mental imagery will not differ in learning by mental rehearsal from those whose usual cognitive mode is devoid of imagery.

Method

Subjects

Male traffic officers (n = 80) from the California Highway Patrol (CHP) volunteered to participate as part of a series of fitness and skill tests conducted by the CHP. Ages ranged from 23 to 57, with a mean age of 36.

Apparatus

The motor task used was learning to balance on a free-swinging platform called a stabilometer. The stabilometer, described in a previous publication (Ryan & Simons, 1981), consisted of a freely swinging platform 48 in. (121.9 cm) x 20 in. (50.8 cm), mounted on ball bearings. The subject stood on the platform and attempted to balance it with a minimum of movement. Each score is equal to 4 degrees of plat- form tilting.

Procedures

A pretest questionnaire was administered outside of the experimental setting. Sub- jects were informed that there was an interest in people's use of mental imagery. They were told that the experimenters wished to sample the general population as to their everyday use of imagery. It was emphasized that it was unknown what propor-

MENTAL IMAGERY 43

tion of the population would fall into which categories of imagery. Verbal examples of two cognitive styles were presented, one illustrating the frequent use of imagery, the other illustrating cognition without imagery awareness. Questions about mean- ing and use of mental imagery were answered. An effort was made to avoid bias toward either style. Subjects were asked to indicate on a checklist which of four categories most closely described their usual behavior: (a) I frequently use imagery in everyday life, (b) On occasions I am aware of images and use them, (c) On occasions I am aware of images but seldom use them, (d) I am seldom or never aware of images in everyday life. Subjects who indicated they frequently used imagery were classified as imagers, whereas those who said they were never aware of images were classified as nonimagers. It had been expected that imagers and nonimagers would be evenly distributed in the experimental population. This was not the case. Only 16 subjects indicated they were nonimagers. Subjects choosing category two or three (occasional use of imagery) were randomly assigned to either a physical practice control group (n = 16) or a no-practice control group (n = 16). Imagers were randomly assigned to one of the two mental practice conditions: imagers asked to use imagery in learning the stabilometer (n = 16) or imagers asked to try not to use mental imagery in learn- ing (n = 16). Nonimagers were also randomly assigned to one of two groups: nonimagers asked to try not to use imagery (n = 8) or nonimagers asked to attempt to use imagery in learning (n = 8).

Subjects were tested individually and privately. The experimenter described and demonstrated how to perform on the stabilometer and any questions were answered. All subjects were encouraged to do their best on all trials. In the physical practice condition, subjects performed a series of 14 trials, each consisting of 30-sec actual balance time, with 30-sec rest intervals between trials. To prevent mental rehearsal between trials, subjects identified pictures tachistoscopically projected at .O1 of a sec.

The performance protocol for the four mental rehearsal groups consisted of two physical trials, 10 mental rehearsal trials, followed by two physical trials. All trials, including the mental rehearsal trials, were 30-sec long, separated by 30-sec tachistoscopic picture identification.

For the two groups asked to use imagery in learning, both the imagers and the nonimagers were instructed to attempt to form visual and kinesthetic images of the task during the initial two trials that they could use during the mental rehearsal series. It was emphasized to the nonimagers in that condition that they had been chosen because they did not use imagery, but that now they were encouraged to at- tempt imagery in learning. On each mental trial subjects were encouraged to "see" and "feel" themselves as vividly as possible balancing on the stabilometer.

For the two groups asked not to use imagery in learning, both the imagers and the nonimagers were asked not to use imagery that might spontaneously occur. They were to use any cognitive means they could utilize (e.g., describe in words) without using imagery. It was emphasized to the mental imagers in this condition that they had been selected because they typically used imagery, but that now the experimenter wanted them to avoid the use of imagery in learning.

In the no-practice condition, subjects were told the experiment was examining reminiscence or spontaneous improvement in performance after rest. They were given two physical trials, followed by a 10-min rest, then two final physical trials. During the 10-min rest, mental rehearsal was prevented by involving subjects in con- versation.

44 RYAN AND SIMONS

To summarize, the four mental rehearsal groups and the no-practice control group all received two trials, a 10-min period of no physical practice, then two additional physical trials, whereas the physical practice groups received 14 trials. Thus, if only physical practice was important, the four mental rehearsal groups and the no- practice control group should not differ from each other, but would all be poorer than the physical practice group. During the 10-min rest, the four mental rehearsal groups had 10 mental trials, giving them the same number of practice sessions as the physical practice group. Thus, if mental rehearsal was as effective as physical prac- tice, the four mental rehearsal groups and the physical practice group should not dif- fer, and all would be better than the no-practice control.

Following performance on the stabilometer, subjects in the four mental rehearsal groups completed a questionnaire in which they rated the perceived effectiveness of their mental rehearsal and indicated the amount and quality of any visual or kinesthetic imagery they had experienced. All subjects were then debriefed as to the true purpose of the experiment.

Results

Performance

A one-way ANOVA of differences in performance between groups in the first and second trials was not significant, F(5, 74) = .75, p 4 9 . Mean change in performance from the last pretest trial (Trial 2) to the first posttest trial (actual Trial 13 for physical practice and actual Trial 3 for all other groups) were greatest for physical practice and least for no practice, as expected. The change for mental rehearsal groups was not predicted, however. Both groups asked to use imagery in the experi- ment had greater mean change than either group asked not to use imagery, regardless of initial proclivity for imagery. An ANCOVA of change scores, using Trial 1 as the covariate, was significant, F(5, 73) = 12.57, p<.001. Adjusted mean change scores are plotted in Figure 1. Also plotted is the actual change made by the physical prac- tice group for Trial 2 to Trial 3 (labeled PPC). This is the point at which the physical practice group had experienced the same number of actual trials as the experimental groups. Both repeated t-tests and Tukey's HSD test for adjusted group means in- dicated no difference between the physical practice group and the mental imagery group that used imagery, t(73) = 1.92, p >.05; no difference between the latter group and the nonimagers who used imagery, t(73) = 1.56, p>.05; and no difference be- tween the nonimagers who used imagery and the remaining groups. When only data from the four experimental groups were analyzed by ANCOVA, with Trial 1 as the covariate, there were significant differences, F(3, 59) = 8.11, pe.001, with both t-tests and Tukey HSD showing no significant differences between the two groups using imagery, t(59), = 1.72, p <.09, and no significant differences between the two nonimagery groups, t(59), = .58, p<.56. The nonimagers who used imagery did not differ significantly from either the nonimagers who did not use imagery, t(59) =

1.75, p<.08, or the mental imagers who did not use imagery, t(59) = 1.22, p<.23. When the change scores for those who initially said they used imagery were com-

bined and compared to the combined scores of those who initially said they did not, there were no significant differences, F(1 , 45) = .lo, p<.75, although actual mean change for the imagery group was numerically greater than the nonimagers. When

Mean Performance Scores for All Conditions

Adjusted Trial 1 ~ Trial 2 Trial 13 Trial 14 Change

Condition M SD M SD M SD M S D M SD

Physical practice

Mental imagery - lmagery

Mental imagery - No imagery 329.75 50.33 261.88 44.02 246.13 39.08 212.13 46.60 15.75 42.54

Nonimager - Imagery 263.50 36.48 245.38 52.55 216.50 79.94 161.38 46.56 28.88 43.77

Nonimager - No imagery 341.00 47.42 277.13 67.68 254.13 52.42 212.75 50.90 23.00 42.68

No practice 308.31 57.67 236.94 52.95 239.44 43.73 194.69 39.28 - 2.50 42.24

RYAN AND SIMONS

NIN PPC

R PP = Physical Practice MI1 = Mental Imagery - lmagery MIN = Mental Imagery- No lmagery N I I = No lmagery - Imagery NIN = No lmagery - No lmagery R = No Practice PPC = Physical Practice - Control

Figure 1-Adjusted mean change from last premental rehearsal trial (Trial 2) to first post- mental rehearsal trial (Trial 3) for all groups. (PP is the change from Trial 2 to Trial 13.) PPC - - -- - - - is the change for the same group from Trial 2 to Trial 3. Each performance score is equal to 4 deg of platform tilting.

initial imagery proclivity was ignored and performance of subjects who were asked to use imagery was combined and compared to those asked not to use imagery, however, ANCOVA indicated significant differences between groups, F(1, 45) = 14.25, p<.001, with the groups asked to use imagery performing significantly better than those asked not to use imagery (Figure 2). Again, the change from actual Trial 2 to actual Trial 3 for the physical practice group is graphed for comparison. Note that the change for physical practice-control and the group that did not use imagery is essentially the same.

The traditional question that has been asked about mental rehearsal has ignored individual differences in imagery and has simply asked, "Will mental rehearsal

MENTAL IMAGERY

U I = Used Imagery NU1 = Not Used Imagery PPC = Physical Practice-

Control

Figure 2-Combined adjusted mean change scores for all subjects asked to use imagery (MII, NII) compared to those asked not to use imagery (MIN, NIN). (PPC is the change in perfor- mance for the physical practice group from Trial 2 to Trial 3.) Each performance score is equal to 4 deg of platform tilting.

enhance performance or learning of motor skill?" When the data of four mental rehearsal groups were combined to form a single "mental rehearsal" group and then compared to the traditional physical practice and no practice, an ANCOVA using Trial 1 as the covariate and change as the dependent variable was significant, F(2,76) = 5.11, pc.03,with both Tukey HSD and repeated t-tests indicating significant dif- ferences between each of the three conditions (Figure 3).

Responses to Posttest Questionnaires

In the four imagery conditions subjects were asked (a) if they used visual or

48 RYAN AND SIMONS

R PP = Physical Practice MP = Mental Practice R = No Practice

Figure 3-Adjusted mean change scores when all mental imagery groups were combined. Each performance score is equal to 4 deg of platform tilting.

kinesthetic imagery in the experiment, (b) how strong the visual or kinesthetic im- agery was, and (c) how helpful each had been. Because the variances between groups were not homogeneous, a nonparametric Kruskal-Wallis (KW) one-way ANOVA was used to assess significance of differences between groups.

For every question, subjects who indicated prior to the experiment they used im- agery responded to the questionnaire in the same way; that is, they reported greater use and strength of imagery than the two groups who initially said they did not use imagery. In only one question, however, ("Did you use kinesthetic imagery"), were the responses significantly different (KW = 8.04, p<.05). This was not related to per- formance since the combined mental imagery group did not perform better than the combined no-imagery group.

It was apparent from inspection of the responses, and in conversation with the

MENTAL IMAGERY 49

subjects during the experiment, that all individuals in the various conditions did not necessarily follow instructions. For example, when imagers were asked not to image, many still reported using imagery. Even some of the nonimagers who were asked not to image reported using imagery. Therefore, all subjects in the four experimental conditions were combined into one group (n = 48), ranked from high to low (or yes - no) on their response to each of the four questions. Performance of subjects scoring high on each question was then compared to performance of subjects scoring low. For each question, approximately 25% of the subjects indicated they did not use imagery or if they did it was weak and of little help. Those subjects were approx- imately evenly distributed among the four experimental conditions.

There were no significant differences in performance between subjects reporting high and low scores on whether they used visual or kinesthetic imagery, or in how helpful visual imagery was. Strength of both visual and kinesthetic imagery seemed to be beneficial. Subjects who reported strong visual imagery had significantly greater changes in performance than those who reported weak visual imagery t(35) = 2.29, p<.03, and strong kinesthetic imagers had significantly greater changes in performance than weak kinesthetic imagers, t(46) = 2.26, p<.03. Finally, subjects who reported more help from kinesthetic imagery had greater changes than those who reported no help, t(46) = 2.80, p<.01.

Discussion

Originally, it was hypothesized that an individual's unique or typical cognitive style was the critical factor in improvement of performance after mental rehearsal rather than use or vividness of mental imagery. Those individuals who typically did not use imagery would be as effective in mental rehearsal as those who did use men- tal imagery. It was specifically hypothesized that the mental imagers who used imagery and the nonimagers who did not use imagery would not differ, and both would be better than the groups who were being asked to perform in a way not usual to them. The data did not substantiate that position, however. There was clear sup- port for the position that vivid imagery enhanced performance after mental rehear- sal. The group that typically used imagery and used imagery in the experiment had the greatest mean improvement in performance of all groups. Of special interest, however, was the group that initially reported no use of imagery in their everyday lives, but was asked to use imagery in this experiment (NII). Although this group had been expected to perform most poorly, their mean improvement in performance was second only to the subjects who previously used imagery and were asked to use im- agery in this experiment (MII). When the two groups asked to use imagery were com- bined and compared to the two groups asked not to use imagery, it was clear that the use of imagery had enhanced performance after mental rehearsal.

Additional support for the facilitating effects of imagery came from the response to posttest questions. Those reporting stronger visual and kinesthetic imagery per- formed better than those reporting weaker images. Although feelings of how helpful visual imagery was did not relate to performance, ratings of the helpfulness of kinesthetic images were related to better performance.

Two assumptions had been made when designing this study; first, imagers and nonimagers would be approximately evenly distributed in the population, and se- cond, the use of a cognitive style different from a person's usual one would result in

50 RYAN AND SIMONS

interference or impaired performance. Both assumptions were at least partially false. It was difficult to find subjects who did not use imagery. As far as the second assumption was concerned, when the imagers were asked to refrain from using im- agery, all expressed difficulty in complying. It is quite reasonable to assume this disrupted their concentration on the task and impaired performance. On the other hand, while some of the imagers reported they were never able to develop images, none expressed distraction from the task of mentally rehearsing, and there was a clear enhancement of the group due to imagery instructions.

There is at least one other possible explanation for the differences in performance between the mental rehearsal groups. It was obvious to all experimental groups that the experiment involved the use of imagery. With the many public and popular reports of enhanced performance due to imagery, it may be that an experimental de- mand or "self-fulfilling prophecy" (Rosenthal & Jacobson, 1968) that imagery would improve performance was created that was sufficiently strong in itself to create the performance difference.

One other point should be made. Although the two nonimagery groups did not perform as well as the imagery groups, it was clear that mental rehearsal even without imagery had been more successful than no rehearsal. Performance of the combined nonimagery groups was virtually the same as the physical practice group after the same number of actual trials (the condition labeled PPC in Figures 1 and 2), in spite of the fact that approximately 10 minutes had elapsed between the second and third trials for the experimental groups. The 10-min rest without mental rehear- sal had resulted in an actual decrease in performance for the so-called reminiscence group.

Thus, in this experiment mental rehearsal did improve performance on the stabilometer relative to a no-practice control group. Although the individuals' reported usual cognitive mode did not affect learning, the use of visual and kinesthetic imagery in mental rehearsal appears significantly better than cognitive styles without imagery.

References

Clark, L.V. Effect of mental practice on the development of a certain motor skill. Research Quarterly, 1960, 31, 560-569.

Epstein, M.L. The relationship of mental imagery and mental rehearsal to performance of a motor task. Journal of Sport Psychology, 1980, 2. 211-220.

Fosbury, D. Fosbury on flopping. Track technique, 1974, 55, 1749-1750. Gallwey, W.T. The inner game of tennis. New York: Random House, 1974. Gallwey, W.T., & Kriegel, B. Inner skiing. New York: Random House, 1977. Marks, D.F. Visual imagery differences on the recall of pictures. British Journal of Psycho-

logy, 1973, 64, 17-24. Marks, D.F. Imagery and consciousness: A theoretical review from an individual differences

perspective. Journal of Mental Imagery, 1977, 2, 275-290. Morrison, A.J. A new way to better golf. New York: Simon & Schuster, 1932. Morrison, A.J. Better golf without practice. New York: Simon & Schuster, 1940. Nicklaus, J. Playing better golf. King Features Syndicate, 1976. Rosenthal, R., &Jacobson, L. Pygmalion in theclassroom. New York: Holt, Rinehart & Win-

ston, 1968.

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Russell, B., & Branch, L. Second wind: The memoirs of an opinionated man. New York: Ran- dom House, 1979.

Ryan, E.D., & Simons, J. Cognitive demand, imagery, and frequency of mental rehearsal as factors influencing acquisition of motor skills. Journal of Sport Psychology, 1981,2, 35-45.

Start, K.B., & Richardson, A. Imagery and mental practice. British Journal of Educational Psychology, 1964, 34, 280-284.

Manuscript submitted: April 7 , 1981 Revision received: July 7, 1981