The purpose of the experiment was to determine the influence of Lissajous feedback on 1:1 bimanual coordination patterns (0 degrees , 90 degrees , and 180 degrees phase lags) when the movement amplitudes of the two limbs were different (30 degrees , 60 degrees ). The present data supports the notion that the lead-lag relationship as well as amplitude assimilation observed in the literature can be partially attributed to the visual-perceptual factors present in the testing environment. When participants are provided integrated feedback in the form of Lissajous plots much of the lead-lag and amplitude assimilation effects were eliminated, and relative phase error and variability were also greatly reduced after only 3 min of practice under each condition.

The effects of physical guidance on learning to perform slalom-type movements on a ski-simulator were examined in 22 participants (18 in Experiment 1, 4 in Experiment 2). In Experiment 1, 1 group of participants practiced the task with ski-poles whereas another group practiced without poles. Retention tests without poles were performed at the end of each of the 2 practice days and 1 day later. Although the use of poles produced more effective performance in terms of movement amplitude during practice, both conditions led to similar amplitudes in immediate and delayed retention. With regard to the efficiency of the movement pattern, the pole group demonstrated a more efficient coordination pattern than the no-pole group did, not only during practice but also in immediate (Day 2) and delayed retention. In Experiment 2, how the poles functioned to enhance the learning of a more efficient movement pattern was examined more closely. The results suggest that physical guidance can have beneficial effects not only on performance during practice but also-under certain conditions-on the learning of motor skills.

Feedback frequency effects on the learning of a complex motor skill, the production of slalom-type movements on a ski-simulator, were examined. In Experiment 1, a movement feature that characterizes expert performance was identified. Participants (N = 8) practiced the task for 6 days. Significant changes across practice were found for movement amplitude and relative force onset. Relative force onset is considered a measure of movement efficiency; relatively late force onsets characterize expert performance. In Experiment 2, different groups of participants (N = 27) were given concurrent feedback about force onset on either 100% or 50% of the practice trials; a control group was given no feedback. The following hypothesis was tested: Contrary to previous findings concerning relatively simple tasks, for the learning of a complex task such as the one used here, a high relative feedback frequency (100%) is more beneficial for learning than a reduced feedback frequency (50%). Participants practiced the task on 2 consecutive days and performed a retention test without feedback on Day 3. The 100% feedback group demonstrated later relative force onsets than the control group in retention; the 50% feedback group showed intermediate performance. The results provide support for the notion that high feedback frequencies are beneficial for the learning of complex motor skills, at least until a certain level of expertise is achieved. That finding suggests that there may be an interaction between task difficulty and feedback frequency similar to the interaction found in the summary-KR literature.

The effects of reduced frequency of presentation of relative-liming knowledge of results (KR) on constant and serial practice and whether response stability is associated with increased generalized motor program (GMP) learning were examined. Participants (N = 40) were asked to sequentially depress 4 keys (2, 4, 8, and 6) on the numeric pad portion of the computer keyboard by using the index fingers of their right hands. The frequency (50% and 100%) with which relative-timing KR was presented was manipulated in constant and in serial practice conditions. The tasks used in both the constant and the serial conditions had the same relative-timing structure, but serial practice had 3 different absolute-timing requirements. The results, which indicated that reduced KR frequency enhances GMP learning in the serial practice condition, replicate the findings of Wulf, Lee, and Schmidt (1994). The reduced frequency of KR effect was not evident for the constant practice groups, however. More interesting was the finding that constant practice was significantly better than serial practice for the development and learning of the GMP. The data also showed that after either constant practice or reduced frequency of KR, response stability was enhanced in comparison with the stability of responses following serial practice and frequent KR. Those findings suggest that when response stability is improved either by reducing the frequency with which KR is presented or by reducing the number of task variations practiced, the development of the GMP is enhanced but parameter specification in transfer tasks tends to be degraded.

Recent experiments have demonstrated that complex multi-element movement sequences were coded in visual-spatial coordinates even after extensive practice, while relatively simple spatial-temporal movement sequences are coded in motor coordinates after a single practice session. The purpose of the present experiment was to determine if the control process rather than the difficulty of the sequence played a role in determining the pattern of effector transfer. To accomplish this, different concurrent feedback conditions were provided to two groups of participants during practice of the same movement sequence. The results indicated that when concurrent visual feedback was provided during the production of the movement, which was thought to encourage on-line control, the participants performed transfer tests with the contra-lateral limb better when the visual-spatial coordinates were reinstated than when the motor coordinates were reinstated. When concurrent visual feedback was not provided, which was thought to encourage pre-planned control, the opposite was observed. The data are consistent with the hypothesis that the mode of control dictates the coordinate system used to code the movement sequence rather than sequence difficulty or stage of practice as has been proposed.

An experiment was designed to determine if the addition of a load altered the effector transfer profile observed in earlier experiments using multi-element movement sequences. The acquisition task required participants to move a horizontal lever (with 0.567kg load) to 16 sequentially projected targets. One group practiced the movement sequence with their right (dominant) limb and another group practiced with their left (non-dominant) limb. Approximately 24h after completion of the acquisition session both groups were administered test blocks (0kg, 0.567kg, and 1.134kg) using their practiced and unpracticed limbs. Decreased and increased loads had minimal effect on test performance. The results indicated that the group trained with their left limb were able to perform the right limb tests as well as the group that trained with the right limb. However, the group that trained with their right limb were significantly slower performing the tests with the left limb than the group that practiced with their left limb. Importantly, the left acquisition limb group maintained the pattern of element durations used during practice on the various tests including transfer to the dominant limb. However, the pattern of element durations for the right acquisition limb group on the left limb transfer tests was altered such that the production of only the fastest produced elements were disrupted. These results suggest that one of the reasons for poor sequence performance when transferring from the right to left is because the sequence structure developed during acquisition and used on the tests lacked access to the appropriate commands or the controller lacked the ability to implement codes that effectively manage the movement dynamics.

Recent experiments have produced mixed results in terms of performance when, after learning a sequential task, the same visual-spatial coordinates or the same motor coordinates were reinstated on a subsequent effector transfer test. Given the diversity of tasks and especially sequence characteristics used in previous experiments, the cross-experimental comparison makes inferences and unambiguous interpretations difficult. The purpose of the present experiment was to determine in a principled manner how the spatio-temporal structure of a sequence influences the way the sequence is represented. The results indicated that after limited amount of practice relatively more simple sequences (S1) are coded more efficiently in a mirror (motor) representation which requires the same pattern of homologous muscle activation. Conversely, relatively more complex sequences (S2) are more efficiently coded in a visual-spatial coordinate system which requires movements to the same spatial locations as during acquisition. The data are also consistent with the notion that sequences with different spatio-temporal structures rely to a different degree on distinct control mechanisms (pre-planned vs. on-line, respectively).

Bimanual 1:1 coordination patterns other than in-phase (0 degrees ) and anti-phase (180 degrees ) have proven difficult to perform even with extended practice. The difficulty has been attributed to phase attraction that draws the coordination between the limbs towards the bimanual patterns of in-phase and anti-phase and variability associated with the activation of non-homologous muscles via crossed and uncrossed cortical pathways. We found participants could very effectively produce a large range of supposedly unstable coordination patterns (between 0 degrees and 180 degrees in 30 degrees increments) after only 3min of practice when integrated feedback (Lissajous plots) was provided and other perceptual and attentional distractions were minimized. These findings clearly indicate that the perception-action system is fully capable of producing a wide range of bimanual coordination patterns and that the reason for the failure to produce these patterns in previous experiments reside in the perceptual information and attentional requirements typically found in experimental testing environments.

Previous research suggests that movements are represented early in practice in visual-spatial coordinates/codes, which are effector independent, and later in practice in motor coordinates/codes (e.g., joint angles, activation patterns), which are effector dependent. In the present experiments, the task was to reproduce 1.3 s patterns of elbow flexions and extensions. An inter-manual transfer paradigm was used in Experiment 1 and an inter-manual practice paradigm was used in Experiment 2. The present results clearly indicated a strong advantage of effector transfer when the motor coordinates available during acquisition were reinstated (Experiment 1) and demonstrate that inter-manual practice with the same motor coordinates results in enhanced retention performance relative to transfer and practice where the same visual-spatial coordinates are used. These results demonstrate that the more effective movement code (motor or visual-spatial) is dependent on the movement sequence characteristics (e.g., difficulty, number of elements, and mode of control [preplanned or on-line]). These results are also interesting because they indicate, contrary to previous findings with more complex movement sequences, that an effective motor code can be developed relatively early in practice for rapid movement sequences.

Three experiments utilizing a 14-element arm movement sequence were designed to determine if reinstating the visual-spatial coordinates, which require movements to the same spatial locations utilized during acquisition, results in better effector transfer than reinstating the motor coordinates, which require the same pattern of homologous muscle activation. Results demonstrated better transfer when visual-spatial coordinates were reinstated than when motor coordinates where reinstated regardless of the amount of practice (1, 4, or 12 days; Experiments 1-3, respectively). Transfer (left to right and right to left) was symmetric when visual-spatial coordinates were reinstated but not when motor coordinates were reinstated. When motor coordinates were reinstated after 12 days of practice and vision occluded, transfer was better from right limb to left than vice versa. The data are also consistent with the notion that multiple codes (visual, spatial, and motor) are developed over practice, with each contributing to transfer performance when the respective coordinates are reinstated. Further, the results indicate a disruption of the linkage (concatenation) between subsequences when one or more coordinates are changed on the transfer test.(PsycINFO Database Record (c) 2009 APA, all rights reserved).