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The Effect of Mental Practice on Performance in aSequential Reaction Time TaskDavid R. Shanks a & Annabel Cameron aa Department of Psychology, University College LondonPublished online: 01 Apr 2010.

To cite this article: David R. Shanks & Annabel Cameron (2000) The Effect of Mental Practice on Performance in aSequential Reaction Time Task, Journal of Motor Behavior, 32:3, 305-313, DOI: 10.1080/00222890009601381

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Journal of Motor Behavior, 2000, Vol. 32, No. 3, 305-31 3

The Effect of Mental Practice on Performance in a Sequential Reaction Time Task

David R. Shanks Annabel Cameron Department of Psychology Unlivarsity College London

ABSTRACT. The effect of mental practice on performance in a dot-lowtion RT task was investigated. Participants (N = 40) were requirtid either to mentally practice, physically practice, or do no practke on an RT task in which the signals appeared in a repeat- ing scyuence. Correct mental practice, as opposed to incorrect menix1 practice and no practice, was predicted to have a positive (enhancing) effect on performance of the RT task. Despite previ- ous c\ idence that mental rehearsal does enhance performance in many perceptual-motor tasks, neither correct nor incorrect mental rehcar:t>al affected subsequent sequence learning; that is, no men- tal prwice effect was observed. That surprising result is discussed in terrip of motivational, psychoneuromuscular, separate memory systeiqs. and transfer-appropriate processing explanations of men- tal practice.

Key w r d s : mental practice, reaction time, sequence learning

ental practice is defined as a training technique in M which the procedures required to perform a task are mentally rehearsed in the absence of actual physical move- ment ( lor ii review, see Driskell, Copper, & Moran, 1994). Researchers have used the method of mental practice in a varietj of ways: to help performers learn new skills, as a prepcrtormance review of a skill, in combination with phys- ical pi actice, and to review and develop performance strate- gieh. Many investigators have studied the use of mental practiL’e for one or more of those purposes.

In . I typical study within this research domain, partici- panls have initially been required to mentally rehearse a task. ( ‘ommon instructions have included asking the partic- ipant 10 relax, to remain still, and to imagine performing the task wccessfully from start to finish. Usually, a control group and a group receiving physical practice are included for ccrmparison. Following mental or physical practice. or both. performance is assessed. Mental practice has been observcd to have a positive (enhancing) effect if the perfor-

mance of the mental practice group exceeds that of the con- trol group on some measure of speed or accuracy.

Across a large body of research, the tindings on effects of mental practice have been mixed. A number of investigators have shown that mental practice is as effective as real prac- tice in the acquisition of skills. For example, Kelley ( 1965) and Maxwell (1968) observed that mental practice was as effective as physical practice in acquiring the overhand vol- leyball serve, and Vandell, Davis, and Clugston (1943) reached a similar conclusion for foul-shooting and dart- throwing skills. Rawlings, Rawlings, Chen, and Yilk ( 1972) found equally beneficial results of mental and physical practice on the pursuit rotor task, and Smith and Harrison (1962) obtained equivalent results for simple eye-hand coordination tasks.

In contrast, in a number of studies mental practice has been found to improve skill acquisition, but not as effec- tively as real practice. That finding represents a weaker view of the effect of mental practice. Twining (1949) found that mental practice did improve performance on a ring- tossing task, but that it was not as effective as real practice. Halverson (1949) found that mental rehearsal enhanced per- formance of a basketball push, but again i t was not as effec- tive as real practice. Similar results have been reported by Steel (1952) and Kelsey (1961) in studies in which partici- pants mentally rehearsed a muscle endurance task.

In various studies, combinations of mental practice and physical practice have been investigated. Overall, the results of those studies suggest that combinations of real

Correspondence address: David R, Shuiiks, Depurtment cf Psy- chology, (Iniversity College London, Cower St., hiidon WCIE 6 BT England. E-mail address: d.shanks @ uclsic. uk

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D. R. Shanks & A. Cameron

and mental practice are as effective as physical practice alone. For example, Waterland (1956) found that a combi- nation of kinesthetic perception and mental practice facili- tated the acquisition of bowling skills. Oxendine (1969) noted a similar improvement in pursuit rotor tracking, the accuracy of a soccer kick, and a modified jump shot. White, Ashton, and Lewis (1979) concluded that a combination of mental and real practice also improves performance of the competitive swimming start.

Finally, in another group of studies either mental practice was found to be ineffective or else the improvements ob- served have been interpreted as resulting from factors other than practice per se. For example, Corbin (1967) found that mental rehearsal was ineffective in improving performance in a unique wand-tossing task, whereas Shick (1970) observed that mental rehearsal was ineffective in improving volleyball and wall volley tasks, and Smyth (1975) obtained similar results for two perceptual motor tasks, mirror draw- ing and rotor pursuit.

Only within the last two decades or so have investigators attempted to integrate the research literature to establish a clear consensus as to whether-and if so, when-mental practice has a positive effect on skill performance. A meta- analytic integration was conducted by Feltz and Landers (1983). They analyzed 60 studies and found that mental practice showed a benefit in task performance of about half a standard deviation (SD). The analysis was criticized by Driskell et al. (1994), however, who emphasized the impor- tance of using stringent selection criteria in a meta-analysis. In the studies included in Feltz and Landers’ meta-analysis, a broad range of different modes of intervention were rep- resented. including combined mental practice and physical treatment conditions, combined mental practice and model- ing interventions, and broadly defined “psyching-up” strategies. Those interventions are not usually considered pure cases of mental practice (Driskell et al., 1994).

Driskcll and his colleagues therefore conducted their own meta-analysis on the studies in the literature. The selection criteria for the analysis specified that there had to be a clear cxainination of mental practice, that is, cognitive rehearsal of a task prior to performance. Furthermore, in the experi- ments examined, the performance of participants engaging in mental practice had to be compared with the performance of participants in a control group who did not engage in practice. The results of the analysis were consistent with those of Feltz and Landers (1983) and indicated that mental practice does have an enhancing and positive effect on per- formance, again of about half a standard deviation. In stud- ies that also included a real practice group, the enhancing effect of physical practice was about .8 SD.

To take the findings a step further, Driskell et al. (1994) invcstigated factors that might mediate the mental practice effect. The following factors were found to be reliably relat- ed to the magnitude of the mental practice effect: the type of task, the expertise level of the participants, the retention interval between practice and performance of the skill, and

the duration of the mental practice session. In terms of the type of task, they found that mental practice is more effec- tive the more the task incorporates cognitive components. For retention interval, the strongest effect is obtained with the shortest interval, or when performance is tested imme- diately after practice. In terms of timing, there is an optimal duration of the mental practice intervention of approxi- mately 20 min. Most interesting, an interaction was found between the type of task and the experience level. For novices, the results indicated a stronger effect of mcntal practice for tasks involving a high cognitive component; whereas for experienced participants, there was no such effect. Presumably, the diversity of results in the literature derives from complex interactions between the factoi s mediating the effectiveness of mental practice.

In the present experiment, we looked to see whether a mental practice effect can be obtained in a new situation that is particularly suitable for addressing the issue of men- tal versus physical practice. The skill to be acquired was perceptual-motor sequence learning in the context of an RT task involving dot location. The sequence-learning proce- dure was developed by Nissen and Bullemer (1 987) and has been used in numerous subsequent implicit learning studies (see Goschke, 1998, for a review), but never with respect lo mental practice. Participants are asked to respond to a targct dot appearing in one of four locations on a computer dis- play. The dot appears in a repeating sequence so that partic - ipants can learn to anticipate the next appearance of the dot. In the present study, participants were briefly trained on the RT task and then either physically practiced the sequcnce. mentally practiced the correct sequence, mentally practiced an incorrect sequence, or received no practice. Following practice, participants performed the target location task on the computer, and finally an assessment was made of thc amount of sequence knowledge participants in each group had acquired.

After many cycles of the sequence, participants can bc shown chronometrically to have learned something aboul the repeating nature of the stimuli (e.g., Nissen & Bullemer, 1987). One can establish that learning has occurred by unexpectedly transfemng the performers to a random, non- repeating sequence. If participants have indeed learncd about the sequence, then their expectation on each trial regarding where the next stimulus will appear should he correct, and therefore they will be able to anticipate thd location. In the transfer stage, those expectations will he violated, and participants will instead have to check then- selves to avoid making incorrect responses, and RTs will thus be increased. A mental practice effect is observed i f the difference in the participants’ RT scores following mentul rehearsal (for the repeating and random sequence) signiti- cantly exceeds that of the control group.

A study reported by Pascual-Leone et al. (1993) encour- aged us to expect a mental practice effect in the prescnt experiment. Those authors explicitly taught participants the repeating sequence before requiring them to perform the

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Mental Practice and Sequence Learning

sequcritial reaction time (SRT) task. Although participants were 7,pecifically told “not to mentally practice by imagin- ing the series of finger movements to do” (p. 595) during the initial sequence-learning phase, the explicit knowledge they acquired was sufficient to allow them to respond very rapidly and to demonstrate accelerated learning in the sub- sequclit SRT test. Because participants in our study (see the folloN ing) acquired explicit sequence knowledge during the mental practice phase, we predicted that they would also show rapid SRT responding.

I n ontrast to previous experiments, an incorrect mental practice group was included in the design of the present experrinent. Participants in that group rehearsed a similar but incorrect version of the sequence. To the best of our knokledge. there have not previously been experiments in which the content of the mental practice task has been maniftulated in that way. The manipulation has clear irnpor- tancr for the motivational account of mental practice (accobints of mental practice effects are examined more fully in the Discussion). According to the motivational account, mental rehearsal increases task motivation and therehy enhances performance. By incorporating the incor- rect ilkental practice group, one can test that idea: If incor- rect arid correct mental practice groups significantly differ from m e another, then a motivational account of mental reheaixal can be ruled out, because effects on motivation should be equivalent.

Wc anticipated that the performance of participants engapitng in correct mental practice would significantly dif- fer froin the performance of participants engaging in incor- rect iiiental practice or in no practice of the dot-location RT task. We also expected that because of interference there would be no effect or even a negative effect of mental prac- tice tor the incorrect rehearsal group.

Method Parti lipants

Fony participants (I9 men, 21 women), all of whom were University College London undergraduates, carried out the expeninent. All reported normal eyesight. The experiment wah cwrried out in a sound-proofed testing room.

Rewtron Erne Task We used a standard IBM-compatible PC and keyboard to

run thc RT task. The task required the participant to respond as quickly and accurately as possible to a target dot appear- ing i n one of four boxes aligned along the bottom of the screeii There were four response keys, v, b, n, and m, cor- responding to the four target location boxes, from left to right. The target location boxes were presented on a blue background. The boxes (3 cm x 2 cm) were aligned along the bottom of the screen 3 cm apart; we refer to them as 1-4, from left to right. The target was a white dot, approximate- ly 3, nrm in diameter, that appeared in the center of the box.

Thti dot appeared in a 12-trial second-order conditional (SOC I sequence that repeated throughout the block. Two

sequences were used, SOC 1 (1 21 3423 14324) and SOC2 (123413214243). Inspection of SOCl and SOC2 shows that they are identical in terms of the frequency of both each stimulus and each transition (see Reed & Johnson, 1994). The two SOC sequences do, however, differ in terms of the third location within each triplet structure. To illustrate this point, note that the first triplet in the SOCl sequence is 121; the target dot will always appear in Box I after it has appeared in Box 1 and then in Box 2. In contrast, the first triplet in the SOC2 sequence is 123; the target dot will always appear in Box 3 after it has appeared in Box 1 and then in Box 2. Participants were therefore able to anticipate the next appearance of the target stimulus. In the random sequence, the target dot appeared in a random order (except that repetitions were not allowed) and there was no repeat- ing higher order triplet structure. The sequence was matched to the SOC sequences in terms of the frequency of each stimulus and the first-order transitions. Participants were unable to anticipate the location of the next target dot.

Within each block, there were 100 trials. The 12-element sequence was repeated eight times with the addition of 4 extra trials of the sequence. Each block started at a random point in the sequence, and the first 4 trials were practice tri- als. Each individual target location trial within the sequence ended once the correct response had been made, and the next target in the sequence appeared 200 ms later. The RT for each trial was measured from the initial appearance of the target at its location to its disappearance, and the com- puter stored that data for further analysis.

Procedure

Each participant was seated in front of the computer and given verbal instructions as to how to carry out the RT task. The participant was informed that there would be four boxes displayed along the bottom of the screen and that a dot would appear in one of them. The participant was asked to respond to the dot as quickly and as accurately as possi- ble with the appropriate response keys: v and b (with the left middle and index fingers) and n and m (with the right index and middle fingers). The response keys corresponded to the target location boxes, from left to right. We initially gave each participant 20 random trials of the dot-location task in order to familiarize them with the task, and then we carried out a training block of 100 trials. Before comnienc- ing the training phase, the participant was informed that there was a sequence in which the dot appeared in the tar- get location boxes. Half the participants in each group were trained on the SOCl sequence and the other half on the SOC2 sequence.

After being trained on Block 1 on either the SOCl or SOC2 sequence, the participant was then assigned to one of four practice groups: real practice (RP), no practice (NP), correct mental practice (MP-C), or incorrect mental practice (MP-I). There were 10 participants in each group and, where relevant, each participant practiced for a duration of approximately 7 min. That was the amount of time partici-

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pants in the RP group required on average to complete their six training blocks (we measured that time in pilot work).

After the initial sequence block, participants in the RP group carried out a further six blocks (600 trials) of the RT Lask. The target dot appeared according to the same sequence that was used in the initial block. Participants were allowed to pause between blocks. Participants in the N P group were presented with a list of 40 anagrams and asked to solve as many as possible within 7 min. The ana- gram were presented on a piece of white A4 paper and were listed down the left-hand side. Participants were asked LO write the solutions in the space provided on the right- hand side.

Participants in the MP-C group were guided by the experimenter through a mental practice phase. They men- tally practiced the same sequence (either SOCl or SOC2) they had seen in Block 1. An approximate transcript of the mental rehearsal guidance to a participant is. given next as an illustration of the procedure. In the exemplar case, the correct sequence was SOCl.

This experiment is examining whether mental practice will enhance your performance on a task. I am therefore going to get you to shut your eyes and mentally rehearse the experi- ment you have just carried out. I am going to break the experiment down into 4 sections and get you to rehearse each section separately and then, eventually, get you to do the whole thing. Please refrain from making any physical actions to help you in rehearsing the task such as tapping your fin- gers, and i f at any point you feel that you need more time to rehearse or you are having any problems please let me know. [Participant now has eyes closed.]

Imagine that you are seated in front of the computer and that your fingers are resting on the appropriate response keys. Examine the four boxes on the screen and now exam- ine your fingers. Your left middle finger should correspond to box 1 (the one on the far left of the screen), your left index should correspond to box 2, your right index finger should correspond to box 3 and your right middle should correspond to box 4 on the far right of the screen.

We’ll now go on to the first section that I want you to rehearsc. Look at the screen. A dot has appeared in box 1 on the far left of the screen, it then appears in box 2, and final- ly in box 1 again. Imagine yourself responding to the dot, think about the action of pressing down on the appropriate response button. Keep on rehearsing this pattern of the dot appearing in box I , box 2, and then box 1.

Okay, we’ll now go onto the second section. A dot has now appeared in box 3 on the far right of the screen and now it’s gone hack to hox 4 and now it’s in box 2. Follow the dot with your eyes as it goes into the different boxes and imag- ine yourself responding. Once again concentrate on the action of pressing down on the response keys and keep on rehearsing this in your head.

We are now going to combine what we have done so far. Look at the screen and concentrate on the boxes and imagine yourself responding when I say the box numbers: 1,2,1,3,4, and 2 . . . 1,2,1,3,4, and 2. Now try and imagine the task so far without any help.

In the third section the dot has now appeared in 3, 1, and then 4. Keep on concentrating on the action of pressing down on the keys and watching the dot as it goes from box to box. We’re now in the fourth and final section. The dot now goes

from 3 to 2 and finally 4. Keep on rehearsing responding with the appropriate fingers as the dot appears in each box. Once again we are going to combine sections 3 and 4 so I am going to say each box number in turn and get you to imagine responding. 3,1,4,3,2,4 . . . 3,1,4,3,2,4. Try and rehearse this without any help.

Finally we’re going to rehearse the whole task from the beginning. I will say the box numbers until such time as you think you can mentally imagine the task unaided. 1,2,1,3,4,2,3,1,4,3,2,4 . . . 1,2,1,3,4,2,3,1,4,3,2,4.

Once the participant could mentally rehearse the dot- location task unaided, he or she was required to verbally state the box numbers out loud. Correct recall of the box numbers indicated that the participant had sequence knowl- edge. Note that participants did not merely learn the num- ber sequence, as opposed to the finger movement sequence. In debriefing, all participants reported mentally rehearsing the finger sequence, and they all knew the assignment of numbers to screen positions.

Participants in the MP-I group were guided by the exper- imenter to mentally rehearse the task that they had just car- ried out. In contrast to the MP-C group, those participants mentally rehearsed an incorrect sequence. If, for example, a participant had been trained on SOCl in Block 1, then he or she mentally practiced SOC2. The transcript for the mental rehearsal guidance was identical to that used for the MP-C group. Participants were led to believe that they were rehearsing the initial training sequence that they had seen in Block 1. Once participants could mentally rehearse the task without guidance and could state the box locations in the correct order (indicating sequence knowledge), they pro- ceeded to the test phase of the experiment.

Each participant was then asked to perform three further blocks of target-location trials. In the first block (Pre), the same sequence (SOC 1 or SOC2) was used as had been used in the initial training phase (Block 1) of the experiment. The second block (Random) was similar, except the dot appeared in the boxes according to a random sequence. In the third block (Post), the initial training sequence was pre- sented again. We presented the random sequence in the sec- ond of those blocks in order to assess skill acquisition: A difference between RTs for the repeating and random sequences indicated sequence knowledge. Participants were allowed to pause between blocks. Both mental practice groups were asked to “look out” for the sequences they had rehearsed so that their performance might be speeded up. The experiment lasted approximately 15 minutes.

Results The mean RTs for each participant for the initial training

block (Block 1) and the three test blocks (Pre, Random, and Post) were calculated for the analysis. For the RP group, we also computed mean RTs on the additional six training blocks they received (Blocks 2-7). In calculating mean RTn. we excluded the first four trials, which were regarded as warm-up trials. RTs over 1,OOO ms were also dropped; those RTs accounted for < 1% of the data across all blocks.

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On the initial training block (see left-hand side of Figure l), there was no significant difference between groups, F(3, 36) = 1.03, MSE = 4,632, indicating that each group was carrying out the RT task at a similar level of performance. For the RP group, after the initial block RTs fell steadily acrosb training Blocks 2-7.

In both the mental practice groups (MP-C and MP-I), all particrpants were able to learn the dot-location sequence withiir the 7 min. Mental practice proceeded without any difficulty. At the end of the mental practice stage, all partic- ipants could verbally report the sequence perfectly.

Mean RTs for the critical test blocks are shown on the right c d Figure 1. It is clear that RTs increased dramatically on thib random block in the RP group, which is consistent with earlier research (e.g., Nissen & Bullemer, 1987) and which demonstrates that sequence learning had taken place after the presentation of many cycles of the sequence in the RT tabk. On the Post block, RTs returned to their earlier level RTs also increased on the Random block in the other three groups, but the increases were considerably smaller. Most interesting was the finding that the increases were almost identical in those groups; hence, mental practice, whether of the correct or an incorrect sequence, seems to have had no impact on skill acquisition.

We calculated the differences between the Random block and the average of the Pre and Post blocks for each partici-

520 540 I 500 c

400 420 1

pant to obtain D (difference) scores; those scores provide an index of sequence knowledge. The mean D score and the 95% confidence interval (CI) for each group arc illustrated in Figure 2. All the D scores were greater than zero, indi- cating that learning of the sequence had occurred in all groups (those scores were all significant, because zero was outside the 95% CIS in each case). Most critical, the RP group had a higher D score than the other groups; the scores of the other groups did not differ from one another. That finding indicates that greater learning of the sequence occurred in the Rp group than in the others.

A one-way analysis of variance was carried out on the D scores across the four groups, yielding F(3, 36) = 5.07, MSE = 1,331, p c .05. In three planned orthogonal con- trasts, with a set at .05/3 = .017, we compared the mean D scores for the RP versus the NP group to evaluate the effects of real practice (Cl), the mean D scores for the NP group versus the MP-C group to evaluate the effects of mental practice (C2), and the mean D scores for the two mental practice groups (C3). C1 was significant, t(36) = 3.41, p < .005, indicating that real practice enhanced sequence knowledge; C2 was nonsignificant ( t c l), indicating that the D scores for the correct mental practice and control groups did not differ significantly; and C3 was also non- significant ( t e l), indicating that the D scores for the two mental practice groups did not differ. The results of the con-

+- Group RP -E+ Group NP + Group MP-C 74-- Group MP-I n

1 2 3 4 5 6 7 Pre Random Post

Block FIGURE 1. Mean reaction time (RT) across blocks for participants in the real practice (W), no practice (NP), correct mental practice (MP-C), and incorrect mental practice (Mp-I) groups. All groups first carried out one block of trials (Block 1 ) with the RT task. The RP group then performed six further blocks (Blocks 2-7) of the RT task, whereas the other groups engaged in mental practice (MP-C and MP-I groups) or in a distractor task (NP group). All groups then performed three further blocks of the RT task with the original training sequence (Pre and Post) or with a block of random trials (Random). The increase in RTs on the random block was a measure of sequence learning.

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RP NP MP-C MP-I

Group FIGURE 2. Mean D Scores (RT on the random block minus the average of RTs on the Pre and Post blocks) for each group. RP = real practice, NP = no practice, MP-C = correct mental practice, and MP-I = incorrect mental practice. Error bars indicate 95% confidence intervals.

trasts supported the conclusion that mental practice had no effect on the acquisition of perceptual-motor sequence knowledge.

One might think that those conclusions are at variance with the mean RTs of the different groups on the Pre block. One might assume that the degree of sequence knowledge across the different groups would be directly manifested in their overall RTs. Instead, the pattern of RTs on the Pre block did not corroborate the pattern of D scores. For exam- ple, the RP group responded no more quickly on average than the NP group. In our view, however, mean RTs can be a very insensitive index of sequence knowledge and are vastly inferior to the interference measures used in this and most other studies. Indeed, just as was found here, there are many examples in previous work where interference scores revealed group differences that were not evident in mean RTs (e.g., Frensch, Wenke, & Riinger, 1999; Schmidtke & Hcucr, 1997).

Discussion Real physical practice of a sequential RT task led to reli-

able increases in sequence knowledge, which is consistent with much previous research (see Goschke, 1998): The mean D score of the RP group was about 100 ms; that rep- resented a sizable interference effect on the random block. Mental practice of the dot-location task was completely ineffective, however, although it endowed participants with complete and accurate knowledge of the sequence. The per- formance of participants engaging in correct mental prac- tice did not exceed the performance of participants engag-

ing in no practice or that of participants in the incorrect mental practice group. Both of those result were unexpect ed. Only physical practice of the task significantly enhanced performance.

The results are surprising because positive mental prac- tice effects have often been reported in the literature (see Driskell et al., 1994). Furthermore, mental practice eftect\ have been reported for simple eye-hand coordination task\ (e.g., Smith & Harrison, 1962). We will discuss possiblc theoretical accounts of mental practice in an attempt to explain the surprising absence of an effect observed here. Motivational, psychoneuromuscular, separate memory sys- tems, and transfer-appropriate processing accounts of men- tal practice are briefly discussed.

One explanation of mental practice effects has been pro- posed in terms of nonspecific factors, of which motivation is perhaps the most obvious example. According to thc motivational account, mental rehearsal increases task moti vation and thereby enhances performance (Richardson, 1967), and in the present experiment we included an incor rect mental practice group to test that idea. We thought that there would be a significant difference in performance between the correct and incorrect mental practice groups, which would rule out a nonspecific account. No mental practice effect was obtained for either group; therefore, the experiment presented an inadequate test of the account Further studies in which incorrect mental practice group\ are included and in which positive mental practice effects are obtained would allow additional tests of the theory.

A second account of mental practice effects is the psy

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chonouromuscular theory, which dates back to Jacobson (1932) That theory holds that mental practice causes miniiie subthreshold activations of the muscles that are actually being used in the physical performance of the skill being learned. According to the theory, those activations are suftic tent to generate minimal kmesthetic feedback through which some learning is mediated. One would have difficul- ty inrerpreting the present results in accordance with the psychoneuromuscular account, however. On the basis of the theorxi. low-level muscular activation during mental practice wouhl be expected to enhance performance in the MP-C group and to retard performance in the MP-I group; but that did not occur in the present experiment.

TL\ o conclusions can be drawn: Either the duration of the menu1 practice session was too short to allow sufficient kine\rhetic feedback. or the muscle activations during men- tal priictice were somehow different from those that occur in the physiLal performance of the dot-location skill. Further testing could be carried out to evaluate those suggestions. In the f i r 4t case, for example, the duration of the mental prac- ticc qcssion could be extended. It seems likely, however, that participants did have sufticient subthreshold kinesthet- ic tedback for learning to occur. After all, the mental prac- tice participants were able to declaratively recall the seyut’nce, which implies that some learning had taken placc Thus, we would argue that, on the basis of this theo- ry. the absence of a mental practice effect is problematic. Explmations in terms of motor output may not be sufficient to acc ount for the present results. In the next part of the dis- cussion, we therefore turn to more cognitive explanations.

Ovcr the last few years, there has been considerable inter- est i i i whether there are dissociable memory systems (e.g., Schauter, 1987; Shanks & St. John, 1994). Researchers have argutd that experimental results and current understanding of brim functioning strongly imply that there are separate memvry systems for declarative (explicit) and procedural (nondeclarative, implicit) knowledge (e.g., Squire, Knowl- ton, Cur Musen, 1993). According to such a view, one can conjtrcture that in the present experiment there was a disso- ciation between two sorts of knowledge. Knowledge gained in t h t perceptual-motor RT task can be seen as essentially procc.dural, whereas knowledge gained through mental rehearsal can be seen as essentially declarative. Because the proclbdural and declarative memory systems are indepen- dent. mental practice was unable to enhance performance on thc prceptual-motor RT task. Using the theory, therefore, one t an account for the data of the present experiment.

Thct theory also provides an explanation for some recent data reported by Reber and Squire (1998), who, like us, used the sequential RT task. Those authors trained one group of participants for many blocks with a repeating seyutme and measured their RTs on a subsequent block of trials on which the sequence was changed. Another group of partit.ipants was shown five cycles of the dot moving accon ding to the repeating sequence and was explicitly inhtrucled to try to learn the sequence. In that phase, partic-

ipants did not react to the dot. Then, the same group per- formed the SRT task. Reber and Squire found that whereas real practice led to a significant increase in response laten- cies on the transfer block, participants who had declarative- ly learned the sequence showed no such increase. Thus, the results were very similar to ours, except that Reher and Squire’s Participants did not mentally practice the RT task. Willingham (1999) has reported similar negative results on transfer between observational sequence learning, which provided participants with declarative sequence knowledge, and subsequent SRT performance.

In contrast, as mentioned in the introductory comments, Pascual-Leone et al. ( 1 993) reported an effect of declarative sequence learning on subsequent SRT performance. What is the basis of the discrepancy between our findings and those of Reber and Squire (1998) and Willingham (19991, on the one hand, and the findings of Pascual-Leone et al., on the other? In our view, the likeliest explanation is that Pascual- Leone and colleagues used a sequence that is much easier to learn than the sort of second-order conditional sequence used here, by Reber and Squire, and by Willingham. For example, the sequence that was used by Pascual-Leone et al. contained a run of four successive locations (4321) which, as many authors have noted, is very salient. Under those conditions, declarative sequence knowledge may be able to affect the speed of procedural sequence learning. An intriguing possibility, therefore, is that the complexity of the sequence determines whether mental practice can be effec- tive or not.

One problem with the procedural-declarative theory is that it makes it difficult to explain the positive mental prac- tice effects previously reported for many eye-hand coordi- nation tasks. Moreover, it is difficult to derive predictions from the theory because there is no obvious way to ascer- tain in advance the degree to which a given task is proce- dural or declarative and would therefore benefit from men- tal practice (Ryan & Simons, 1981). Finally, we have argued that if the hallmark of declarative knowledge is that it is consciously accessible, then essentially all of the knowledge participants acquire in the SRT task is declara- tive. Sequence knowledge appears always to be accessible on the sorts of direct tests that are supposed to assess declar- ative knowledge (Shanks & Johnstone, 1999).

The transfer-appropriate processing view (Kolers & Roediger, 1984) can be contrasted with the separate memo- ry systems account. In the former theory, i t is proposed that all knowledge can be placed within a framework of skills and procedures. Most critical, the theory states that the expression of knowledge is dependent upon the means by which the information is acquired. Thus, if the acquisition and performance of a task involve similar operations, the expression of knowledge should be good as a result of pos- itive transfer of procedures. In contrast, if the acquisition and performance of a task involve dissimilar operations, the expression of knowledge should be poor because no trans- fer of procedures has occurred.

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The transfer-appropriate processing theory provides a plausible interpretation of the present results. In this exper- iment, the physical practice group acquired knowledge of a perceptual-motor skill in the practice phase of the experi- ment. In the test phase, knowledge of the skill was cxprcsscd effectively because the task required the same operations as those acquired in the practice phase. In the mental practice groups, the participants acquired knowl- edge of a mental imagery skill. Although mental imagery is known to share many underlying neurophysiological processes with actual movement (e.g., Decety, 1996), one can plausibly argue that the underlying operations involved i n mentally imagining the SRT task are dissimilar in certain fine details to the operations involved in actually doing the task. For example, the precise timing operations required to perform the SRT task were not likely to be rehearsed during mcntal practice. In the test phase, knowledge acquired dur- ing mental practice was therefore not expressed because the perceptual-motor task required different operations.

The procedural view appears to be a plausible account of thc fact that mental practice did not affect performance in the present study. Tho predictions can be derived from the theory for further testing. The first is that if the test phase is inorc geared lo the expression of knowledge of operations acquired during mental rehearsal, then a mental practice effect would be observed. One way of determining the cor- rectness of the prediction would be to require participants in B lest phase to predict where the dot will appear on the screen on each trial (e.g., Willingham, Nissen, & Bullemer, 1989). A practice cffect would be expected on such a pre- diction task for participants who mentally rehearse the task, hut no practice effect would be expected for participants who physically rehearse the task.

The second prediction is that if the mental practice phase involves a closer overlap with the operations used in physi- cal practice, then a mental practice effect would be expect- ed. One could test that prediction by asking participants to tap their fingers while mentally rehearsing the sequence, hence incorporating a motor component into mental prac- tice. Similarly, another group of participants could mental- ly imagine carrying out the RT task while watching the dots appear in the correct sequence on the computer screen, hence incorporating a perceptual component into mental practice.

I n conclusion, the results failed to demonstrate any men- tal practice effect in the performance of a sequence-learning task. The experiment highlights the need for a clear theoret- ical framework. An understanding of the underlying princi- ples mediating mental practice, and how those principles rclate to each other, is an important area for continuing investigation.

ACKNOWLEDGMENT We thank Celia Heyes for her help in designing the experiment.

'The research described here was supported by a grant from the United Kingdom Economic and Social Research Council (ESRC).

The work is part of the program of the ESRC Centre for Econom- ic Learning and Social Evolution, University College London.

REFERENCES Corbin, C. B. (1967). The effects of covert rehearsal on the devel-

opment of a complex motor skill. Journal of General Psycholo-

Decety, J . (1996). The neurophysiological basis of motor imagery. Behaviourul Bruin Research, 77, 45-52.

Driskell, J. E., Copper, C., & Moran, A. (1994). Does mental prac-. tice enhance performance? Journal of Applied Psychology, 79. 48 1-492.

Feltz, D. L., & Landers, D. M. (1983). The effects of mental prac tice on motor skill learning and performance: A meta-analysis. Journal of Sport Psychology, 5, 25-57.

Goschke, T. (1998). lmplicit learning of perceptual and motor sequences: Evidence for independent learning systems. In M. A. Stadler & P. A. Frensch (Eds.), Handbook of implicit learninx (pp. 401444). Thousand Oaks, CA: Sage.

Halverson, L. E. (1949). A comparison of three methods of teuch- ing motor skills. Unpublished master's thesis, University 01' Wisconsin.

Jacobson, E. (1932). Electrophysiology of mental activities. Amer- ican Journal of Psychology, 44, 677-694.

Kelley, D. A. (1965). The relative effectiveness ojselected mental practice techniques in high school girls ' acquisition of a gross motor skill. Unpublished master's thesis, University of Wash- ington, Seattle.

Kelsey, I. B. (1961). Effects of mental practice and physical prac- tice upon muscular endurance. Research Quarterly, 32, 47-54.

Kolers, P. A., & Roediger, H. L. (1984). Procedures of mind. Jour nal of Verbal Learning and Verbal Behavior, 23, 425-449.

Maxwell, S. M. (1968). The e$ects of mental practice on 1116,

learning of the overhand volley-ball serve. Unpublished mas- ter's thesis, Central Missouri State College, Warrensburg, MO.

Nissen, M. J., & Bullemer, P. (1987). Attentional requirements 01'

learning: Evidence from performance measures. Cognitive P sy-

Oxendine, J. B. (1969). Effects of mental and physical practice on the learning of three motor skills. Research Quarterly, 40,

Pascual-Leone, A., Grafman, J., Clark, K., Stewart, M., Mas- saquoi. s., Lou, J.-s., & Hallett, M. (1993). Procedural learning in Parkinson's disease and cerebellar degeneration. Annu/s r ! / Neurology, 34, 594-602.

Rawlings, E. I., Rawlings, I. L., Chen, S. S., &Yilk, M. D. (1972). The facilitating effects of mental rehearsal in the acquisition oU rotary pursuit tracking. Psychonomic Science, 26, 71-73.

Reber, P. J., & Squire, L. R. (1998). Encapsulation of implicit and explicit memory in sequence learning. Journal of Cognitive Neuroscience, 10, 248-263.

Reed, J., & Johnson, P. (1994). Assessing implicit learning with indirect tests: Determining what is learned about sequencc structure. Journal of Experimental Psychology: Learning, Mem ory, and Cognition, 20, 585-594.

Richardson, A. (1967). Mental practice: A review and discussion, R. 2. Research Quarterly, 38, 264-273.

Ryan, E. D., & Simons, J. (1981). Cognitive demand, imagery, and frequency of mental rehearsal as factors influencing acquisitioii of motor skills. Journal of Sport Psychology, 3, 35-45.

Schacter, D. L. (1987). Implicit memory: History and current sta.. tus. Journal of Experimental Psychology: Learning, Memory, and Cognition, 13, 501-518.

Schmidtke, V., & Heuer, H. (1997). Task integration as a factor iii secondary-task effects on sequence learning. Psycho/ogica/ Research, 60, 53-71.

gy, 76, 143-150.

chology, 19, 1-32.

755-763.

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Mental Practice and Sequence Learning

Shank, D. R.. B Johnstone, T. (1999). Evaluating the relationship bctwtcn explicit and implicit knowledge in a sequential reaction tirric iask. Journal of E.uperimerito1 Psvchalogy: Leirrning, M V I I I O ~ ~ . urrd Cognition, 2.5, 1435-1451.

Shank\. 0. R.. XC St. John, M. F. (1994). Characteristics ofdisso- ciithh. human learning systems. Behaviorul und Bruin Sciences, 17, .u11-437.

Shich. I . (1970). Effects of mental practice on selected volleyball skill?; liir cdlege women. Research Quur/erlv, 41, 88-94.

Snulh. 1 . . E.. B Harrison, J . E. (1962). Comparisons of the effects ol v i w ~ l . motor, mental and guided practice upon speed and the acciii :icy id performing a simple eye-hand coordination task. Rrw Irrrh Qutrrterly, 33, 299-307.

Smyth. M. M. (1975). The role of mental practice in skill acquisi- tion .lournu1 (!/'Motor Behavio,: 7, 199-206.

Squirc. L R . , Knowlton, B.. & Musen, G . (1993). The structure and 1 Irpanization of memory. Anrzuul Review of Psychology, 44, 453 '405.

Steel, \Y L. I 1952). The effect of mental practice in the acquisition 01 it inotor skill. Journal ofphysical Education, 44, 101-108.

Twining, W. E. (1949). Mental practice and physical practice in learning a motor skill. Research Quurferly, 20, 432-435.

Vandell, R. A,, Davis, R. A,, & Clugston, H. A. (1943). The func- tion of menpal practice in the acquisition of motor skills. Jour- rial of'Cenerul Psychologyn 29, 243-250.

Waterland, J. G. (1956). Effects ofmenrul prirctice combined with kinesthetic perception when the pracrice precedes overt perjor- munce ? f a mofcrr skill. Unpublished master's thesis, University of Wisconsin.

White, K. D.. Ashton, R., & Lewis, S. (1979). Learning a complex skill: Effects of mental practice, physical practice, and imagery ability. International Journal of Sport Psychology, 10, 7 1-78.

Willingham, D. B., Nissen, M. J. , & Bullemer, P. (1989). On the development of procedural knowledge. Journal of Experimen- tal Psychology: Learning, Memory, and Cognition. 15, 1047-1060.

Submitted December 24, I998 Revised August 3, 1999

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