An Analysis of World Weightlifting Records

Abstract

Summary knowledge of results (KR) involves delaying the presentation of KR until a predetermined number of trials has been completed. Schmidt, Young, Swinnen, and Shapiro (1989) found an optimal summary length of 15 trials (compared to 1, 5, and 10) and Schmidt, Lange, and Young (1990) found an optimum length of 5 trials (compared to 1, 10, and 15) for 1 and 2 kinematic degree of freedom timing tasks, respectively. Experiment 1 was designed to determine the optimal summary length for learning a simple isometric force production task. The results indicated better retention for the 16-trial summary than for 8- or 1-trial summaries. Experiment 2 was an initial attempt to determine the locus of the 16-trial summary effect. Specifically, Experiment 2 focused on the role played by both the information provided in the summary presentations and the practice per se of the first 14 trials in the 16-trial block. The results suggest KR is important to ensure response stability. However, it also appears important to restrict the subject's immediate utilization of KR. This latter requirement may potentially aid the parameterization process, resulting in a reduction in response bias.     

Summary knowledge of results

Summary knowledge of results (KR) involves delaying the presentation of KR until a predetermined number of trials has been completed. Schmidt, Young, Swinnen, and Shapiro (1989) found an optimal summary length of 15 trials (compared to 1, 5, and 10) and Schmidt, Lange, and Young (1990) found an optimum length of 5 trials (compared to 1, 10, and 15) for 1 and 2 kinematic degree of freedom timing tasks, respectively. Experiment 1 was designed to determine the optimal summary length for learning a simple isometric force production task. The results indicated better retention for the 16-trial summary than for 8- or 1-trial summaries. Experiment 2 was an initial attempt to determine the locus of the 16-trial summary effect. Specifically, Experiment 2 focused on the role played by both the information provided in the summary presentations and the practice per se of the first 14 trials in the 16-trial block. The results suggest KR is important to ensure response stability. However, it also appears important to restrict the subject's immediate utilization of KR. This latter requirement may potentially aid the parameterization process, resulting in a reduction in response bias.     

Summary and frequency of KR presentation effects on retention of a motor skill

This experiment investigates the recent proposal of Schmidt, Young, Swinnen, and Shapiro (1989) that summary knowledge of results (KR) improves skill retention. In Schmidt et al.'s experiment, however, summary length varied concomitantly with the frequency of KR presentation. The current investigation held KR presentation frequency constant while manipulating the number of trials seen in the summary KR display. Subjects were required to perform a timing task on a linear slide. Five groups (n = 12) of subjects participated in acquisition trials then in 10-min and 2-day delayed no-KR retention tests. In 4 conditions, subjects completed each acquisition block without any KR, but following each block they received KR on either 15, 7, 3, or 1 of the 15 trials performed in that block. In the final condition subjects received immediate KR. Analysis of the absolute constant error (magnitude of CE) data for acquisition revealed all groups improved with practice and the immediate KR group performed better than all the summary groups which in turn did not differ significantly. Analysis of the magnitude of CE retention data found performance to be worse on the 2-day retention test for all groups. The effect of condition was significant. The 1/1 group had lower error scores than all other groups, which in turn were not significantly different. Analyses of variable error (VE) revealed only that VE decreased with practice. These findings suggest frequency of KR presentation may be the basis for the summary KR effect found by Schmidt et al. (1989).     

Precision Knowledge of Results and Motor Performance: Relationship to Age

In motor skill performance and retention the complexity of knowledge of results should interact with the child's processing rate. This rate has been demonstrated to increase with age. Two experiments were designed to assess this hypothesis. In Experiment 1, 30 7-year-old and 30 10-year-old boys were randomly assigned within age level to three knowledge of results (KR) conditions: no KR, general KR, and precise KR. Performance was assessed on a vertical positioning task at two angles, 60° and 100°, for 10 performance trials. The preciseness of KR interacted with age and the degree of the angle, indicating that at the more difficult angle (60°) preciseness may have been detrimental to the performance of the 7-year-olds but beneficial to the 10-year-olds. At the easier angle (100°), precise KR improved performance for both age groups. In Experiment 2, 27 second-grade and 27 fourth-grade children were randomly assigned within age groups to the same three levels of KR preciseness. A horizontal curvilinear positioning task was used as the motor task and subjects were given 40 acquisition and 19 KR withdrawal trials. Results suggested that while KR was better than no KR during learning, the level of KR preciseness was of minor importance. However, the preciseness of KR during acquisition was of considerable value after KR was withdrawn (retention phase). The older children were able to use more precise KR to form a perceptual trace more resistant to forgetting, while the younger children were unable to use the additional information contained in precise KR.     

The Effect of Knowledge of Results Delay and the Subjective Estimation of Movement Form on the Acquisition and Retention of a Motor Skill

Abstract

This study examined the effects of knowledge of results (KR) delay and subjective estimation of movement form on the acquisition and retention of a motor skill. During acquisition, four groups of participants performed 60 trials of a throwing accuracy task under the following conditions: (a) immediate KR, (b) delayed KR, (c) immediate KR + form estimation, and (d) delayed KR + form estimation. Retention tests of throwing accuracy and outcome error estimation in the absence of visual KR were administered 5 min and 24 hours following acquisition. Throwing accuracy was significantly higher during acquisition but significantly lower during retention for immediate-KR participants than for delayed-KR participants. However, participants who estimated their movement form during acquisition produced significantly higher throwing accuracy and lower estimation error during retention than those who did not.     

How persistent and general is the contextual interference effect?

The persistence and generality of the contextual interference (CI) effect was tested using a rapid sequential aiming task. Participants (N=48) practiced three movement patterns for three blocks of 18 trials under a blocked (BL) or random (RA) schedule. Movement patterns were displayed and KR provided throughout practice and testing. A 24-hr delayed knowledge of results (KR) retention test included three blocks of 18 trials, followed by a transfer test of a single new movement pattern. In contradiction of the CI effect, RA practice provided an advantage for RA retention only, not BL retention. Furthermore, group differences at transfer were not persistent. Hence, RA practice does not necessarily provide enhanced, context-free learning, but it is essential training for task switching. Overall the findings reveal limited persistence and generality of the CI effect.     

Divided attention in bimanual aiming movements: effects on movement accuracy

The role of focusing attention on one limb or both limbs in a bimanual aiming task was investigated in two experiments. Participants were prompted to focus attention on either limb (Experiment 1) or were free to choose their attentional strategy (Experiment 2). Fifty-two college-aged participants made quick, bimanual lever reversals in the sagittal plane over 20 degrees and 60 degrees in 210 ms to the reversal point. In both experiments, spatial accuracy was better when participants focused their attention on a single limb compared to the nonattended limb and when they paid attention to both limbs. However, no differences were shown on a no-knowledge of results (KR) retention test when participants paid attention to both limbs. In the second experiment, differences were maintained on a no-KR retention test when participants continued to select their own attentional strategy, although the statistical effect was smaller than in the first experiment. The findings suggested that the movement parameter selection process benefited from attentional focus.     

Composition of Practice: Influence on the Retention of Motor Skills

Abstract

The purpose of these experiments was to investigate further the variable practice effect found by Shea and Kohl (1990). Experiment 1 was an initial attempt to determine the locus of the retention benefits demonstrated by subjects provided variable practice experiences. All groups received 20 acquisition blocks consisting of five test trials per block at a target of 150 N. The interval between test trials was either unfilled or filled, with additional trials consisting of the same target force, variable target forces, or practice on an unrelated motor task. The results indicated retention was not incremented (relative to an unfilled interval) by requiring subjects to perform an unrelated motor task in the intertest–trial interval. However, when the intertest–trial interval was filled with practice on related motor tasks, retention was significantly improved. Experiment 2 assessed the impact of increasing the number of related motor tasks interpolated between test trials. The results indicated filling the intertest–trial interval with one motor task resulted in large retention benefits relative to an unfilled interval. Further increases in the number of related motor tasks (3) interpolated between test trials resulted in only modest increments to retention. The results were consistent with the elaboration perspective proposed by Shea and Zimny (1983). The elaboration perspective proposes that the simultaneous presence of related items in working memory facilitates interitem elaborative and distinctive processing that ultimately results in retention benefits.     

The Effects of a Single Reminder Trial on Retention of a Motor Skill

Two experiments investigated the effects of a single reminder trial on immediate and delayed retention. Experiment 1 determined if beneficial effects of a reminder trial were a function of task order. Immediate retention performance benefited only when the reminder trial was practiced in the first block of trials. Experiment 2 added a 24-hr delayed retention test to examine the long-term benefits of a reminder trial. Retention performance was enhanced over both delay intervals. The long-term effect extended previous research (Shea & Titzer, 1993) that documented effects after 10 min. The use of a single reminder trial established that intertask comparisons between multiple reminder trials were not a precondition for the reminder trial effect as postulated by Shea and Titzer.     

Systematically increasing contextual interference is beneficial for learning sport skills

Abstract

To better understand the contextual interference effect, in two experiments we investigated a form of practice schedule that provided novices with systematic increases in contextual interference. This new type of practice schedule was compared with traditional blocked and random scheduling for two types of sports skills. In Experiment 1, we tested the hypothesis that practising variations of the same task with systematic increases in contextual interference would lead to superior performance compared with blocked or random scheduling. Participants practised golf putting tasks following a blocked, random or increasing schedule, which involved initial blocked trials, followed by serial practice trials, and ended with random scheduling. Participants who followed the increasing schedule had superior retention test performance. In Experiment 2, we tested if these learning benefits were observed when learning tasks controlled by different generalized motor programs. Participants practised three different basketball passes (chest, overhead, single arm) in a blocked, random or increasing schedule. Participants practising with gradual increases in contextual interference performed better on retention and transfer tests than participants practising with blocked or random scheduling. The results of these two experiments indicate that a practice schedule offering systematic increases in contextual interference facilitates skill learning.     

The role of reduced frequency of knowledge of results during constant practice

Two experiments were conducted to further examine the effects of reduced knowledge of results (KR) frequency on the learning of motor skills during constant practice. In Experiment 1, participants in five KR conditions (100% KR, 50% KR-fade, 50% KR-reverse fade, 50% KR-alternative, and 50% KR-random) practiced a movement timing task. In Experiment 2, participants in two KR conditions (100% KR and 50% KR-fade) practiced a waveform reproduction task. The results of both experiments failed to indicate that reduced KR frequency was more effective in promoting learning than the 100% KR conditions. The present study adds to the increasing number of experiments that do not find a benefit of reduced KR frequency on learning in constant practice.     

Feedback After Good Trials Enhances Learning

Recent studies (Chiviacowsky & Wulf, 2002, 2005) have shown that learners prefer to receive feedback after they believe they had a “good” rather than “poor”trial. The present study followed up on this finding and examined whether learning would benefit if individuals received feedback after good relative to poor trials. Participants practiced a task that required them to throw beanbags at a target with their nondominant arm. Vision was prevented during and after the throws. All participants received knowledge of results (KR) on three trials in each 6-trial block. While one group (KR good) received KR for the three most effective trials in each block, another (KR poor) received feedback for the three least effective trials in each block. There were no group differences in practice. However, the KR good group showed learning advantages on a delayed retention test (without KR). These results demonstrated that learning is facilitated if feedback is provided after good rather than poor trials. The findings are interpreted as evidence for a motivational function of feedback.     

Retroactive interference effects of mentally imagined movement speed

In two retroactive interference experiments, we assessed the effect of mentally imagined movement speed on subsequent motor performance. All participants performed a sequential motor action at three speeds during a baseline test and a retention test. During the retention interval of Experiment 1, the participants (n = 50) physically performed the action at a slow speed, physically performed it at a fast speed, imagined it at a slow speed, imagined it at a fast speed, or performed a no-practice control task. In Experiment 2, the participants (n = 24) imagined the movement, overtly vocalized words, or both, all at a slow speed. The results revealed that the speed of the imagined motor action affected the speed of subsequent performance in the retention test and that imagery and physical practice were functionally equivalent. The results are consistent with Lang's bio-informational theory.     

Forthcoming events

Abstract

We conducted two experiments to assess the effect attentional focus has on learning a complex motor skill and subsequent performance under secondary task loading. Participants in Experiment 1 learnt a golf putting task (300 practice trials) with a single instruction to either focus on their hands (internal focus) or the movement of the putter (external focus). No group differences were evident during learning or retention. Differences between the groups were only apparent under secondary task load; the external group's performance remained robust, while the internal group suffered a drop in performance. Verbal protocols demonstrated that the internal group accumulated significantly more internal knowledge and more task-relevant knowledge in general than the external group. Experiment 2 was designed to establish whether greater internal focus knowledge or greater explicit rule build up in general was responsible for performance breakdown. Two groups were presented with a set of six internal or external rules. Again, no performance differences were found during learning or retention. During the secondary task, both groups experienced performance deterioration. It was concluded that accumulation of explicit rules to guide performance was responsible for the internal group's breakdown in performance under secondary task loading and may be responsible for some of the performance differences reported previously.     

The effects of different knowledge of results spacing and summarizing techniques on the acquisition of a ballistic movement

The present study crossed three knowledge of results summarizing techniques (single-trial KR, summary KR, and average KR) with two spacing conditions (KR on every fifth trial-20%- and KR on every trial-100%). Participants (n = 10 per group) performed 80 acquisition trials of a ballistic movement task involving both a temporal and spatial goal, followed by 30 immediate (10 min) and 30 delayed (2 days) no-KR transfer trials. For the spatial goal, performance was less accurate (absolute constant error) for the 20% spacing condition than the 100% condition during acquisition, but more accurate during delayed transfer. No effects were significant for variable error. For the temporal goal, performance was more accurate for the summary and average conditions than the single-trial KR condition; however, this effect was only present within the 20% spacing condition and only during Block 1 of acquisition. A similar effect held for variable error as well, except that the effect persisted for acquisition and transfer. It was concluded that the spacing of KR is more influential in promoting spatial accuracy than the summarizing of KR.     

Feedback after good trials enhances learning

Recent studies (Chiviacowsky & Wulf, 2002, 2005) have shown that learners prefer to receive feedback after they believe they had a "good" rather than "poor" trial. The present study followed up on this finding and examined whether learning would benefit if individuals received feedback after good relative to poor trials. Participants practiced a task that required them to throw beanbags at a target with their nondominant arm. Vision was prevented during and after the throws. All participants received knowledge of results (KR) on three trials in each 6-trial block. While one group (KR good) received KR for the three most effective trials in each block, another (KR poor) received feedback for the three least effective trials in each block. There were no group differences in practice. However the KR good group showed learning advantages on a delayed retention test (without KR). These results demonstrated that learning is facilitated if feedback is provided after good rather than poor trials. The findings are interpreted as evidence for a motivational function of feedback.     

Delayed Visual Feedback While Learning to Track a Moving Target

Abstract

Two studies investigated the effects of delayed visual feedback on manual tracking. In Experiment 1, individuals practiced with visual feedback provided either immediately (0 delay) or with a 333-ms delay. During acquisition, the 0 delay group performed with less error than the 333-ms delay group. A retention test with 0 delay feedback was performed with the least error by the 0 delay group. A transfer test using a different 0 delay tracking pattern, was performed with the least error by the 333-ms delay group. In Experiment 2, individuals practiced at six different delays. Error increased as training feedback delay increased. For retention there were no differences between the delay groups during the 0 delay retention. At a 417-ms retention, test error decreased as training feedback delay increased. Results indicate that error during acquisition does not necessarily impair learning and that feedback delays can be beneficial for learning.     

Maximizing Performance Feedback Effectiveness through Videotape Replay and a Self-Controlled Learning Environment

This study was designed to examine whether participants who could control the schedule of performance feedback (KP) would learn differentially from those who received a rigid feedback schedule while learning a complex task. Participants (N = 48) were randomly assigned to self-controlled KP (SELF), summary KP (SUMMARY), yoked control (YOKE), or knowledge of results only (KR) conditions. Data collection consisted of an acquisition phase and a 4-day retention phase during which right-handed participants performed a left-handed ball throw. Overall, throwing form improved across trial blocks during acquisition, with the SUMMARY, SELF, and YOKE groups showing more improvement than the KR group. During retention, the SELF group retained a higher level of throwing form and accuracy in comparison to the other groups. Results suggest that when given the opportunity to control the feedback environment, learners require relatively less feedback to acquire skills and retain those skills at a level equivalent to or surpassing those who are given more feedback but receive it passively.     

主观估计错误活动、结果反馈时机与运动技能的学习

采用键盘敲击任务探讨学习者主观估计错误活动、结果反馈时机(knowledge of results,简称KR)对运动技能学习的影响.抽取90名右利手的在校大学生,随机分为:主观估计无KR组、主观估计及时KR组、主观估计延迟KR组,算术活动无KR组,算术活动及时KR组,算术活动延迟KR组(组间性别均衡设计).主观估计错误活动组在练习间以口头报告的形式评估自己刚才操作总时间的误差,算术活动组按照实验员的要求进行数字算术口头运算.无KR组不提供KR,及时KR组在主观估计错误活动或算术活动后即刻获得KR,延迟KR组则延迟4s获得KR.第1-2天,6组受试者在各自的条件下分别练习,每天练习108次.第3天,练习后,休息10min,使用原任务进行保持测试10次,要求受试者每次测试后口头报告自己操作的总时间.第4天,使用原任务进行保持测试10次,要求受试者每次测试后口头报告自己操作的总时间.结果显示:(1)练习后从事主观估计错误活动,并能及时获得KR的学习者,保持测试的绩效最好;(2)主观估计错误活动影响提供KR的适宜时机.     

Retroactive interference effects of mentally imagined movement speed

In two retroactive interference experiments, we assessed the effect of mentally imagined movement speed on subsequent motor performance. All participants performed a sequential motor action at three speeds during a baseline test and a retention test. During the retention interval of Experiment 1, the participants (n = 50) physically performed the action at a slow speed, physically performed it at a fast speed, imagined it at a slow speed, imagined it at a fast speed, or performed a no-practice control task. In Experiment 2, the participants (n = 24) imagined the movement, overtly vocalized words, or both, all at a slow speed. The results revealed that the speed of the imagined motor action affected the speed of subsequent performance in the retention test and that imagery and physical practice were functionally equivalent. The results are consistent with Lang's bio-informational theory.