Sequential effects after practice with the dominant and non-dominant hand on the acquisition of a sliding task in schoolchildren

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1 This article was downloaded by: [Tel Aviv University] On: 01 March 2015, At: 02:41 Publisher: Routledge Informa Ltd Registered in England and Wales Registered Number: Registered office: Mortimer House, Mortimer Street, London W1T 3JH, UK Laterality: Asymmetries of Body, Brain and Cognition Publication details, including instructions for authors and subscription information: Sequential effects after practice with the dominant and non-dominant hand on the acquisition of a sliding task in schoolchildren Oliver Senff a & Matthias Weigelt b a University of Jena, Germany b Saarland University, Saarbrücken, Germany Published online: 09 Jun To cite this article: Oliver Senff & Matthias Weigelt (2011) Sequential effects after practice with the dominant and non-dominant hand on the acquisition of a sliding task in schoolchildren, Laterality: Asymmetries of Body, Brain and Cognition, 16:2, , DOI: / To link to this article: PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the Content ) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities

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3 LATERALITY, 2011, 16 (2), Sequential effects after practice with the dominant and non-dominant hand on the acquisition of a sliding task in schoolchildren Oliver Senff University of Jena, Germany Matthias Weigelt Saarland University, Saarbrücken, Germany This study was designed to investigate sequential effects after practice with the dominant and non-dominant hand on the acquisition of a new motor task. A total of 64 middle school children were asked to practise a cent-slide task, which required them to slide coins from one side of a cardboard into a circular target on the opposite side. Four groups practised this task within different practice schedules: (1) participants practised only with their dominant hand (right-only group); (2) participants used only their non-dominant hand (left-only group); (3) participants started to practise the skill with their dominant hand and then switched to their non-dominant hand (right-to-left group); or (4) participants started to practise the skill with their non-dominant hand and then switched to their dominant hand (leftto-right group). The acquisition of the task was facilitated after initial practice with the non-dominant hand. This was reflected in a better retention of the task and a stronger performance under a modified testing situation of the left-to-right group when compared to all other groups. Also, the left-only group showed larger interlimb transfer effects to the untrained hand than the right-only group. It is concluded that the sequence in which the dominant and non-dominant hands are used to practise influences the acquisition of new motor tasks. Keywords: Skill acquisition; Motor learning; Interlimb transfer; Hemispheric specialization. Address correspondence to: Matthias Weigelt, Saarland University, Institute of Sport Science, University Campus B8.1, Saarbrücken, Germany. m.weigelt@mx.uni-saarland.de The present study was conducted by the first author as a partial requirement to receive the Teachers Education degree at the University of Jena, Germany. We would like to express our gratitude to Dr Gerhard Kirchner for supporting the project and to Dr Tino Stöckel for an extended discussion on the topic. Also, we thank Dr Michael Peters and two anonymous reviewers for helpful comments on an earlier version of this manuscript. # 2010 Psychology Press, an imprint of the Taylor & Francis Group, an Informa business DOI: /

4 228 SENFF AND WEIGELT Interlimb transfer of learning refers to the observation that practising a task with one hand (or foot) can also improve performance with the opposite hand or foot (Magill, 2001). Most research in support of interlimb transfer focused mainly on the acquisition of simple movement tasks, involving finger tapping (Laszlo, Baguley, & Bairstow, 1970), writing and drawing (Parlow & Kinsbourne, 1989; Raibert, 1977), key-pressing (Taylor & Heilman, 1980), pursuit rotor tracking (Byrd, Gibson, & Gleason, 1986; Parker-Taillon & Kerr, 1989), or adaptation of pointing movements to visuo-motor perturbations (Sainburg & Wang, 2002, Wang & Sainburg, 2004a) as well as dynamic perturbations (Bagesteiro & Sainburg, 2002; Wang & Sainburg, 2004b). However, a smaller number of studies have also demonstrated an interlimb transfer effect for more complex tasks. These later studies investigated dribbling and kicking skills in soccer (Haaland & Hoff, 2003; Teixeira, Silva, & Cavalho, 2003), dribbling and shooting in basketball (Stöckel, Hartmann, & Weigelt, 2007; Stöckel, Weigelt, & Krug, in press), and performing particular dance routines (Puretz, 1983). Interestingly, all of these studies have reported an asymmetry in the amount of transfer between the opposite limbs, irrespective of whether they utilised simple or complex tasks. More specifically, the amount of interlimb transfer to the untrained hand (or foot) differed after practice with the dominant vs non-dominant hand (or foot). This suggests sequential effects on the acquisition of motor skills, such as that the initial limb practised (dominant vs non-dominant) influences the amount of learning with the opposite limb. Sequential effects on interlimb transfer can be explained with the specific requirements relative to the perceptual and motor components of a particular task (Carson, 1989; Teixeira, 2000; Wang & Sainburg, 2007). In fact there is much support for the selective processing of different task components in the two brain hemispheres during the control of movements (Birbaumer, 2007; Goodale, 1990; Serrien, Ivry & Swinnen, 2006). The left brain hemisphere is primarily responsible for the temporal and sequential control of movements (i.e., the control of movement trajectories), whereas visual-spatial information (i.e., the control of final position and target precision) is mainly processed in the right brain hemisphere (for an overview see Serrien et al., 2006). Such a lateralisation of brain functions is in line with the dynamic dominance hypothesis of motor control (Sainburg, 2002; Sainburg & Eckhardt, 2005) and with a more general model of brain asymmetries and hemispheric specialisation, which assumes that distributed brain networks cooperate during motor performance (e.g., Birbaumer, 2007; Gazzaniga, Ivry, & Mangun, 1998; Serrien et al., 2006). The latter model suggests that both hemispheres are likely to be involved in the performance of any complex task, but with each contributing in their specialized manner (Gazzaniga et al., 1998, p. 369). Voluntary movements are therefore controlled by two specialised brain hemisphere/limb systems, each stabilising different features

5 BILATERAL PRACTICE AND SKILL ACQUISITION 229 of task performance (Sainburg, 2002; Sainburg & Kalakanis, 2000; Wang & Sainburg, 2007). With regard to the present study, the efficient processing of visual-spatial information in the right brain hemisphere benefits the specialised hemisphere/limb system of the right brain/left hand in motor tasks with high spatial accuracy requirements. Because most interlimb transfer studies only examined the amount of transfer to the untrained hand (or foot) after practice with the dominant vs non-dominant hand (or foot), little is known about the long-term effects of practising motor skills with both hands in a sequential order (i.e., one hand after the other). An example of such a sequential practice schedule would be to start learning with the dominant hand for a certain amount of time before continuing with the non-dominant hand for the same amount of time, or vice versa. If the order in which both hands are involved mattered, then differences in learning should be observable relative to whether the dominant or non-dominant hand was practised first. These learning differences would be an indication of sequential effects. Recent evidence in support of such sequential effects comes from two studies by Stöckel and colleagues, who investigated the acquisition of a shooting skill (Stöckel et al., 2007) and a dribbling task (Stöckel et al., in press) in children s basketball. Both studies used a sequential practice schedule, including the same amount of practice with the dominant and non-dominant hand, but in opposite order for two groups. The results showed a better acquisition of shooting and dribbling (respectively) for those children, who started practising with their nondominant hand. Specifically, in both studies this schedule (i.e., nondominant-to-dominant hand) resulted in persistent learning effects and a better transfer of the particular skill to a new testing situation. The authors explained their results with the general model of hemispheric specialisation alluded to above and concluded that motor tasks that used the processing of visual-spatial information should initially be practised with the nondominant hand, in order to involve the specialised hemisphere/limb system (i.e., right brain/ left hand) early on in the learning process. Afterwards, motor learning will benefit from stronger transfer to the non-specialised hemisphere, when the skill is practised with the dominant hand. The purpose of the present study was to further investigate sequential practice effects on the acquisition of a cent-slide task with high spatial accuracy requirements. To this end, participants were asked to slide coins from one side of a piece of cardboard into a circular target on the opposite side. This aiming task therefore required the efficient processing of visual-spatial information. Four groups were included in the study: Two experimental groups started to practise the task either with their dominant or non-dominant hand, before switching to the contralateral hand (with equal amounts of practice on both sides). These experimental groups are referred to as the right-to-left group and left-to-right group, respectively, and

6 230 SENFF AND WEIGELT they allow for the evaluation of the two different bilateral practice schedules and their selective influences on motor learning. In addition we included two control groups who practised the task either only with their dominant hand (right-only group) or only with their non-dominant hand (left-only group) throughout the whole study. These control groups allow for a comparison of single-hand practice with the two sequential practice schedules, as well as for an evaluation of interlimb transfer to the untrained hand after the acquisition phase. In line with previous studies, examining tasks that required the efficient processing of visual-spatial information (Stöckel et al., 2007, in press), we expected to observe greater learning effects for those groups that started the acquisition phase with their non-dominant hand. More specifically, the left-to-right group should outperform the rightto-left group, and greater learning effects were expected to show for both hands; the dominant and the non-dominant hand respectively. This should be reflected in a better retention (as a measure of persistent changes) of the task and a stronger performance under a modified testing situation. Also, the left-only group should show larger interlimb transfer to the untrained hand than the right-only group. Participants METHOD Participants were 64 schoolchildren (29 girls and 35 boys) from the fifth and sixth grade (ranging from 10 to 12 years, mean age10.9 years) of a German middle school. Parents of all children gave their informed consent for their child s participation prior to the experiment. We tested young children because this sample of learners is most often confronted with the acquisition of novel skills (e.g., in physical education classes). The findings of the present study should therefore be of great practical relevance for the organisation and optimisation of bilateral practice schedules. All children were classified as right-handed by their habit of eating with a spoon, using a pen, and throwing a ball. None of the children had prior experience with the task. Apparatus and task The perceptual-motor task used in this study was originally developed by West and Stanovich (1997), and in the following we refer to it as the sliding task. The sliding task required participants to slide 10-cent coins over a wooden table surface from one end into a horizontal round target at the opposite end (Figure 1). The dimension of the table was 95 cm by 210 cm. The target s

7 BILATERAL PRACTICE AND SKILL ACQUISITION 231 Figure 1. The experimental set-up, with the primary sliding task on the left-hand side (A) and the modified sliding task on the right-hand side (B). Both tasks required participants to slide cent coins across a table into a target circle on the opposite side. radius was 35 cm, and its outer limits were 17 cm away from the left and right side, as well as 13 cm away from the end of the board. The target consisted of a total of seven concentric circles (radii5 cm; 10 cm; 15 cm; 20 cm; 25 cm; 30 cm; 35 cm, respectively), where the middle circle was the bull s eye. Participants also performed in a modified sliding task. This task was included to examine possible transfer effects to a condition in which the target was occluded from the participant s sight. To this end a wooden occluder was placed at a distance half way to the target on the table. The occluder was vertically supported by two stands 3 cm above the table surface and its dimension were 75 cm by 40 cm. The set-up allowed participants to slide the coin underneath the occluder, but not to see the target circle. This prevented participants from receiving any visual feedback about their performance. The task itself, however, was similar in all respects to the sliding task, except for the occlusion of the target. Design and procedure The 64 participants were randomly assigned to one of the four treatment conditions (n16/condition): (1) participants practised the skill only with their right hand (right-only group); (2) participants used only their left hand (left-only group); (3) participants started to practise the skill with their right hand for 40 trials and then switched to their left hand for another 40 trials (right-to-left group); or (4) participants started to practise the skill with their

8 232 SENFF AND WEIGELT left hand for 40 trials and then switched to their right hand for another 40 trials (left-to-right group). The initial test protocol lasted 1 day and included a pretest, the learning phase, the first test repetition (posttest), and the second test repetition (short-term retention test). Seven days later this was followed by a third test repetition (long-term retention test). Each participant practised individually. They received knowledge of results (KR) through visual feedback after each trial. On the first day each participant completed the initial test protocol (pretest), in which each hand was separately tested for 10 trials. The starting hand was counterbalanced over all participants and remained constant over the series of test repetitions to follow (a total of three pretestposttest test repetitions). Then the learning phase followed for 80 trials in which each participant practised the skill according to her/his treatment condition. The initial test protocol was repeated for the first time (posttest) immediately after the learning phase was finished. The second test repetition followed 10 minutes after the first test repetition. Seven days later participants returned for the long-term retention test (third test repetition). On this occasion, participants were additionally tested in the modified sliding task (i.e., without visual feedback) for 10 trails on each hand separately. Dependent variables and data analysis Spatial accuracy was assessed as a function of radial error (RE), corresponding to the distance of the final resting position of the cent coin from the bull s eye. Participant s performance was then analysed in a 4 (group: right-only vs left-only vs right-to-left vs left-to-right)4 (test: pretest vs posttest vs short retention vs long retention)2 (hand: left vs right) analyses of variance (ANOVA) with repeated measures on test and hand was performed. The factor group was tested between participants and the factors test and hand within participants. To analyse participants performance in the modified sliding task, a 4 (group: right-only vs left-only vs right-to-left vs left-to-right)2 (hand: left vs right) ANOVA was calculated. Both the right-only and the left-only group are of further interest, because their performance on the untrained hand in the posttest can be taken as a direct measure for transfer of learning from the trained to the untrained hand (i.e., interlimb transfer). To analyse such interlimb transfer effects, the posttest data of the untrained hand were analysed in an independent samples t-test for the left-only and right-only groups.

9 BILATERAL PRACTICE AND SKILL ACQUISITION 233 Sliding task RESULTS Performance improvements in sliding accuracy for the four groups after the pretest are shown in Figure 2. Here, lower RE scores indicate an improvement of performance over the course of the study. The ANOVA revealed a significant main effect for test, F(3, 180)16.553; pb.001. Pairwise comparisons between pretest performance (RE9.72) and all other test repetitions indicated that participants improved significantly in the posttest (RE8.73 cm) and the short retention test (RE8.50 cm) (both psb.001), but not in the long retention test (RE9.50 cm). The main effect for hand was also significant, F(1, 60)8.778; pb.01. Accordingly, participants performed better with their right hand (RE8.87 cm) than with their left hand (RE9.35). Importantly, there was a significant grouptest interaction, F(6, 120)2.284; pb.05, indicating differences in performance between groups relative to the test repetitions. There was no significant main effect of group, and there were no other significant interactions. A first inspection of Figure 2 suggests a difference between the groups for the long retention test. To further explore the two-way interaction of grouptest for these differences, a one-way ANOVA was performed on the long-term retention test data. 1 The ANOVA confirmed the differences between groups to be significant, F(3, 63)8.639; pb.001, and post hoc comparisons provided statistical support for lower RE scores in the left-toright group (RE8.18 cm), as compared to the right-only group (RE cm), the left-only group (RE9.50 cm), and the right-to-left group (RE10.13 cm) in the long-term retention test (all psb.05; two-tailed t-tests; Bonferroni adjustments for multiple comparisons applied). Modified sliding task Figure 3 shows the mean REs of the four groups and their left- and righthand performance in the modified sliding task. The ANOVA revealed a significant main effect for hand, F(1, 60)11.057; pb.01, which showed that participants were better with their right hand (mean RE8.87 cm) than with their left hand (mean RE9.83 cm). The main effect for group was also significant, F(1, 60)8.810; pb.001. Post hoc pairwise comparisons 1 There was a main effect of hand, but no significant interaction of hand with any other factor. Thus the data are collapsed across hands, because hand did not have a selective effect on the twoway interaction of group test. Any differences between the groups to be observed in post hoc comparisons therefore affected both hands equally.

10 234 SENFF AND WEIGELT Figure 2. The mean radial error scores for the different tests, collapsed across both hands. The dotted line marks the average pretest performance of all groups (RE9.7 cm) and allows for the evaluation of each group s performance after the learning phase. Error bars indicate the between-participant standard errors. Figure 3. The mean REs of the four groups for left-hand and right-hand performance in the modified sliding task. Error bars indicate the between-participant standard errors. indicated that the mean RE of the left-to-right group (mean RE8.09) was lower than those of all other groups (all psb.05; Bonferroni adjustments for multiple comparisons applied). There was no difference between the other groups. Also, there was no significant handgroup interaction. Interlimb transfer The mean RE scores for the untrained hand in the posttest were 8.22 cm for the left-only group (untrained handright hand) and 9.76 cm for the

11 BILATERAL PRACTICE AND SKILL ACQUISITION 235 right-only group (untrained handleft hand). The independent samples t-test confirmed this difference between both groups to be significant, t(30) 2.219; pb.05. This significant difference indicates asymmetrical effects of transfer between the trained and untrained hand, with a larger amount of interlimb transfer from the trained left to the untrained right hand. DISCUSSION The aim of the present study was to test the selective effects of two sequential practice schedules (right-to-left hand vs left-to-right hand) on the acquisition of a new motor task (i.e., cent-slide task) and to compare them to the learning effects of single-hand practice (left hand vs right hand only). In line with a general model of brain asymmetries and hemispheric lateralisation (e.g., Gazzaniga et al., 1998; Serrien et al., 2006) it was hypothesised that an early training of the brain hemisphere/limb system specialised for the processing of visual-spatial information (i.e., right brain/left hand) would benefit motor learning, because successful performance in the cent-slide task required the integration of visual-spatial information and a high degree of spatial accuracy. The present results support this hypothesis, showing greater learning effects for the experimental group with initial practice of the nondominant hand. This was reflected by the significant improvement of the left-to-right group, with better performance in the retention test (signifying greater persistence of the task) and a greater proficiency under a modified testing condition in which the participant s vision of the target was occluded, as compared to the right-to-left group and the two control groups. Most importantly, these learning benefits were observed when testing performance with the dominant and the non-dominant hand. This pattern of results is in line with previous studies exploiting the sequential practice paradigm (Stöckel et al., 2007, in press) and it suggests that the order in which a particular motor task is practised with the two hands influences the acquisition of the task. The advantage of using sequential practice schedules for the acquisition of new motor tasks with high spatial accuracy demands can be further appreciated when comparing the results of the left-to-right group to singlehand practice. Here, it is important to note that the left-to-right group practised the task only half as much with the dominant and the nondominant hand, as compared to the left-only group and the right-only group, respectively. However, the left-to-right group outperformed the rightonly group with the dominant hand and the left-only group with the nondominant hand in the sliding task (with and without vision of the target). The two control groups only showed some short-term learning effects after the acquisition phase, but returned to their level of pretest performance in

12 236 SENFF AND WEIGELT the retention test, and thus did not show any persistence of the task. This surprising outcome indicates that sequential practice schedules can be even more efficient for motor learning than practising a new task only with one hand. This observation extends the findings of previous studies that used the sequential practice paradigm (Stöckel et al., 2007, in press), but did not include control groups with single-hand practice. The comparison of the two control groups provides further insight into the direction of interlimb transfer for the sliding task. To this end, sliding performance in terms of target accuracy with the untrained hand was tested after the acquisition of the motor task with the dominant hand (right-only group) or non-dominant hand (left-only group). Because both groups practised the task for exactly the same amount of time, any advantage of one group for the performance of the untrained hand can be directly attributed to differences in interlimb transfer. The left-only group demonstrated greater target accuracy with the untrained hand, signifying larger interlimb transfer effects from the non-dominant to the dominant hand. This direction of interlimb transfer is at odds with a series of studies on aiming movements by Sainburg and colleagues, which reported better transfer of final position accuracy in the opposite direction (Sainburg & Wang 2002; Wang & Sainburg 2003; Wang & Sainburg 2004a, 2004b). There are three important differences between the tasks used in Sainburg s laboratory and the present study, which might have contributed to the contradicting results. First, the present task was ballistic in nature, as it required propelling an object into a target circle, rather than only moving one s hand to a steady-state final position. Second, their tasks often involved an adaptation of manual performance to either visually rotated target locations (e.g., Sainburg & Wang, 2002; Wang & Sainburg, 2004a) or novel inertial dynamics (Wang & Sainburg, 2003, 2004b). No such adaptation was necessary in the present task. Third, Sainburg and colleagues used centre-out movements, requiring participants to move from one fixed start location to different target locations (aligned on a circle). This was also different in the present task, where cent coins had to be slid to one fixed target location on the other end of the table. Although the hand s movement across the table when sliding the coin was not recorded, it is most reasonable to assume that there was some variability in the position each time the coin left the index finger. If this assumption were true, then participants propelled the coin from different positions on the table into the fixed target location on the other end. Together, the differences in these specific task features may have affected the pattern of intermanual transfer in the present study. The impact of fixed vs variable start and target locations on intermanual transfer was recently investigated by Wang and Sainburg (2007). Two groups of participants performed aiming movements with the dominant vs nondominant hand, moving either from one fixed start location to three

13 BILATERAL PRACTICE AND SKILL ACQUISITION 237 different target positions or from three different start locations to one fixed target position, respectively. With the dominant hand, target accuracy was best when reaching from one fixed start location to multiple targets, whereas with the non-dominant hand, target accuracy was best when moving to a single target from multiple start locations. To the best of our knowledge, the direction of transfer between the two hands for conditions in which participants move from different start locations to a single target location has not been investigated. However, if we assume that the coins were propelled from different positions on the table to the fixed target location, then the present results suggest intermanual transfer from the non-dominant to the dominant hand. A systematic investigation of intermanual transfer effects under these conditions should therefore be a topic of further research. In the following, the results of the present study relative to sequential practice and intermanual transfer are considered together for the effective organisation of motor learning schedules. The superiority of the left-to-right group in the acquisition of the sliding task most likely resulted from positive transfer effects between the two hands. This notion is supported by larger transfer effects to the untrained hand after practice with the non-dominant hand, as revealed by comparing the performance of the left-only and rightonly group. Thus, after practising the task with the specialised brain hemisphere/limb system using their non-dominant hand, participants continued the acquisition with the dominant hand starting from a higher level of performance. The inferiority of the right-to-left group may be a result of proactive and retroactive interference effects, selectively affecting the dominant and non-dominant limb. Such interference effects can be observed when two tasks are acquired in close succession (e.g., Goedert & Willingham, 2002; Krakauer, Ghilardi, & Ghez, 1999; Panzer, Wilde, & Shea, 2006). Proactive interference arises when the consolidation processes of the first task interfere with the acquisition of the second task (i.e., second task suffers), whereas retroactive interference means that consolidation of the first task is disturbed by the acquisition of the second task (i.e., first task suffers) (cf. Schmidt & Lee, 2005; Zach et al., 2005). For the right-to-left group, we suggest that initial training with the non-specialised brain hemisphere/limb system produced the following interference effects, acting upon motor learning in the second part of acquisition: Proactive interference hindered the acquisition of the motor task with the non-dominant hand. At the same time, retroactive interference disrupted the consolidation processes of the task previously acquired with the dominant hand. As a result, participants of the right-to-left group suffered from the particular hand order in which they practised the sliding task, whereas the left-to-right group benefited from the opposite schedule. Taken together, the present findings highlight the positive effects of sequential practice schedules on the acquisition of new motor tasks. The

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