Augmented Kinematic Feedback for Motor Learning

Although the study of feedback about goal achievement (knowledge of results, KR) has been important for the development principles of augmented information feedback in simple skills, there is reason to question the generalizability of these findings to many common learning situations. A more appropriate type of information for skill learning appears to be augmented kinematic (or kinetic) feedback regarding the movement pattern. The experiments presented here extend recent findings about KR to a paradigm involving kinematic feedback. In Experiment 1, we examined how several kinds of temporal and spatial kinematic information supplement KR in learning. Spatial kinematic variables were more effective than temporal variables, as indicated by performance in a retention test without kinematic feedback. In Experiment 2, we manipulated the schedule of augmented kinematic feedback in a method that paralleled previous KR work. We contrasted averaged schedules of augmented feedback, in which information was given either after every trial or as averaged information after every set of five trials. On retention tests without kinematic feedback given 1 day and 1 week after acquisition, averaged schedules led to enhanced performance over an every-trial format. Together, these results begin to define the variables important in kinematic feedback, and suggest that this feedback may influence learning in ways parallel to KR.     

Fine motor deficiencies in children with developmental coordination disorder and learning disabilities: an underlying open-loop control deficit

Thirty-two children with Developmental Coordination Disorder (DCD) and learning disabilities (LD) and their age-matched controls attending normal primary schools were investigated using kinematic movement analysis of fine-motor performance. Three hypotheses about the nature of the motor deficits observed in children with LD were tested: general slowness hypothesis, limited information capacity hypothesis, and the motor control mode hypothesis. Measures of drawing movements were analyzed under different task conditions using a Fitts' paradigm. In a reciprocal aiming task, the children drew straight-line segments between two targets 2.5 cm apart. Three Target Sizes were used (0.22, 0.44, and 0.88 cm). Children used an electronic pen that left no trace on the writing tablet. To manipulate the degree of open-loop movement control, the aiming task was performed under two different control regimes: discrete aiming and cyclic aiming. The kinematic analysis of the writing movements of the 32 children with DCD/LD that took part in the experimental study confirmed that besides learning disabilities they have a motor learning problem as well. Overall, the two groups did not differ in response time, nor did they respond differently according to Fitts' Law. Both groups displayed a conventional trade-off between Target Size and average Movement Time. However, while movement errors for children with DCD/LD were minimal on the discrete task, they made significantly more errors on the cyclic task. This, together with faster endpoint velocities, suggests a reduced ability to use a control strategy that emphasizes the terminal control of accuracy. Taken together, the results suggest that children with DCD/LD rely more on feedback during movement execution and have difficulty switching to a feedforward or open-loop strategy.     

A Comparison of Two References for Using Knowledge of Performance in a Motor Task

In the present study, the learning of a task in which the goal of the movement was not isomorphic with a specific movement pattern was examined. The subjects' (N = 48) goal in the task was to be both spatially and temporally accurate in reaching 4 targets with a right arm lever movement. After each acquisition trial, the displacement profile of the movement just produced was provided to all subjects as knowledge of performance (KP). The relative effectiveness of 2 possible references, with which subjects could compare the KP, was examined. One of the references examined was knowledge of results (KR), which was provided by reporting the total absolute timing and amplitude errors from the 4 targets. The other reference examined was a criterion template (CT), which was defined as the most efficient movement pattern for reaching the 4 targets. In the feedback display, CT was superimposed on the displacement profile of the movement just produced. A factorial design, in which 2 levels of KR (KR, no KR) were crossed with 2 levels of CT (CT, no CT), produced 4 feedback conditions. After 120 acquisition trials with feedback, immediate and delayed retention tests without feedback and a reacquisition test with KR (20 trials per test) were conducted. Acquisition results indicated that KR was a better reference than CT for per-forming the timing aspect of the movement and for producing the generalized motor program (GMP) associated with the most efficient movement pattern. Delayed retention results showed that KR was also a better reference than CT for learning the most efficient GMP. The calibration strategy undertaken by subjects who were provided with KR during acquisition explains the superiority of the KR reference. The calibration strategy is compared with the pattern-matching activity that was probably undertaken by subjects who had received CT as a reference.     

Kinematic information feedback for learning a rapid arm movement

The experiments reported examine the notion that knowledge of results (KR) about the outcome of a response does not provide the necessary information for optimizing performance in many skilled activities. The effect of traditional KR was contrasted with various kinematic feedback parameters in the acquisition of a single degree of freedom response requiring the minimization of movement time. Experiment 1 showed that the presentation of discrete kinematic information feedback (peak accelaration, time to peak accelaration, and velocity at the target location) did not facilitate performance over movement-time KR. Experiment 2 revealed that presentation of a computer generated velocity-time representation of the movement as terminal information feedback improved performance over movement-time KR. This facilitation occured even without knowledge of the kinematics for optimal performance. The findings suggest that the task criterion specifies the appropriate information feedback for skill learning in that the information feedback must match the constraints imposed upon response output.     

Exploring the kinaesthetic sensitivity of skilled performers for implementing movement instructions

The capability to effectively control or adapt a movement pattern based on instructional feedback is essential for effective motor skill learning in high-level sport, as it is in other domains such as rehabilitation or music. Despite this, little is known about the capabilities of skilled athletes to use kinematic feedback to purposefully modify complex movements. This study examined the accuracy with which skilled junior tennis players could translate specific kinematic feedback into appropriate modifications of their service actions. Participants were required to either increase or decrease maximum knee flexion or shift impact position laterally by incremental amounts. Further, participants were required to execute their serve with the smallest increase and decrease in these kinematic components as they could consciously produce. Inherent variability within the desired target parameters was calculated to add context to the athlete’s accuracy. Results demonstrated that while participants had considerable control over their movements, only some instructions were executed with accuracy greater the variability normally present within their movement. As the required change in knee flexion and impact position increased, absolute accuracy of implementation decreased. These findings are discussed with reference to the smallest controllable changes produced by the athletes and the variability within their actions.     

Terminal Feedback Outperforms Concurrent Visual,Auditory, and Haptic Feedback in Learning a Complex Rowing-Type Task

Augmented feedback, provided by coaches or displays, is a well-established strategy to accelerate motor learning. Frequent terminal feedback and concurrent feedback have been shown to be detrimental for simple motor task learning but supportive for complex motor task learning. However, conclusions on optimal feedback strategies have been mainly drawn from studies on artificial laboratory tasks with visual feedback only. Therefore, the authors compared the effectiveness of learning a complex, 3-dimensional rowing-type task with either concurrent visual, auditory, or haptic feedback to self-controlled terminal visual feedback. Results revealed that terminal visual feedback was most effective because it emphasized the internalization of task-relevant aspects. In contrast, concurrent feedback fostered the correction of task-irrelevant errors, which hindered learning. The concurrent visual and haptic feedback group performed much better during training with the feedback than in nonfeedback trials. Auditory feedback based on sonification of the movement error was not practical for training the 3-dimensional movement for most participants. Concurrent multimodal feedback in combination with terminal feedback may be most effective, especially if the feedback strategy is adapted to individual preferences and skill level.     

Sensory feedback in the learning of a novel motor task

The role of different forms of feedback is examined in learning a novel motor task. Five groups of ten subjects had to learn the voluntary control of the abduction of the big toe, each under a different feedback condition (proprioceptive feedback, visual feedback, EMG feedback, tactile feedback, force feedback). The task was selected for two reasons. First, in most motor learning studies subjects have to perform simple movements which present hardly any learning problem. Second, studying the learning of a new movement an provide useful information for neuromuscular reeducation, where patients often also have to learn movements for which no control strategy exists. The results show that artificial sensory feedback (EMG feedback, force feedback) is more powerful than "natural" (proprioceptive, visual, and tactile) feedback. The implications of these results for neuromuscular reeducation are discussed.     

Sensory Feedback in the Learning of a Novel Motor Task

The role of different forms of feedback is examined in learning a novel motor task. Five groups of ten subjects had to learn the voluntary control of the abduction of the big toe, each under a different feedback condition (proprioceptive feedback, visual feedback, EMG feedback, tactile feedback, force feedback). The task was selected for two reasons. First, in most motor learning studies subjects have to perform simple movements which present hardly any learning problem. Second, studying the learning of a new movement can provide useful information for neuromuscular reeducation, where patients often also have to learn movements for which no control strategy exists. The results show that artificial sensory feedback (EMG feedback, force feedback) is more powerful than “natural” (proprioceptive, visual, and tactile) feedback. The implications of these results for neuromuscular reeducation are discussed.     

Attention focusing instructions and coordination bias: Implications for learning a novel bimanual task

Four groups learnt a novel bimanual coordination movement pattern under instructions designed to manipulate focus of attention. It was predicted that instructions directing attention onto the effects of the action would facilitate learning. Three groups received demonstrations of the required 90° relative phase movement. Two of the demonstration groups also received instruction directing attention either towards the feedback (EXTERNAL), or the relationship between their arm movements and the feedback (RELATION). The third group received no attention directing instructions (DEMO). A final group was only provided with goal relevant feedback (NO DEMO). A scanning task enabled coordination bias to be assessed pre-practice. This was conducted to ensure task novelty and assign participants equally across groups based on strength of bias to in- and/or anti-phase. Acquisition rate was slower for the DEMO only group, especially compared to the EXTERNAL group. Additionally, participants biased to in-phase (as compared to anti-phase) during the scanning trial also showed high error early in practice. These differences remained in retention. Irrespective of feedback condition the DEMO group evidenced the most error in retention. However, all groups were affected by the removal of on-line feedback, although the attention-directing instructions provided during practice somewhat decreased the negative effects associated with feedback removal. Overall, the in-phase-biased participants were most affected by withdrawal of feedback. It was concluded that movement demonstrations alone do not facilitate learning of a novel coordination task, unless additional goal-directed instruction is provided. Additionally, individual differences in coordination bias pre-practice can be used to predict learning rate and quality.     

Neural mechanism underlying self-controlled feedback on motor skill learning

The present study investigated the neural mechanisms of self-controlled (SC) feedback underlying its learning advantages. Forty-two participants, including 24 females (16.43 ± 2.61 years) and 18 males (17.56 ± 0.86 years), were randomly assigned to a SC or yoked (YK) group. The 6-key-pressing task with a goal movement time was adopted as the experimental task. The behavioral results showed that the SC group demonstrated superior performance in transfer; however, the differences in retention did not reach statistical significance. Event-related potential analyses revealed that the SC group exhibited larger post-stimulus and post-feedback P3 amplitudes than the YK group in the frontal regions; these amplitudes were larger in the YK group in the parietal regions. The post-response error positivity amplitude was found to be larger in the YK group than in the SC group. These results suggest that SC feedback may allow the learner to more actively process the task stimuli and feedback information, and contributes to enhancing the learner’s motivation and attachment to the task being practiced. The present study provides a neurophysiological explanation for why SC feedback is effective in learning a new motor skill.     

Kinematic information feedback and task constraints

The experiments were designed to examine the effect of task constraints on the influence of kinematic information feedback to facilitate the acquisition of discrete arm movements. The findings of Experiments 1 and 3 revealed that when the criterion kinematic trajectory was an increasing acceleration function, the most effective control space representation for kinematic feedback (i.e. position-time; velocity-position) was the one that matched the error criterion to be minimized. Furthermore, in Experiment 1 the velocity-position feedback condition led to greater performance error than the discrete knowledge of results of movement time or integrated position-time error. Experiment 2 showed that kinematic information feedback of the movement trajectory (position-time; velocity-position) did not facilitate acquisition of a constant velocity criterion, in contrast to knowledge of results of movement time or integrated velocity-position error. Collectively the findings suggest that the interaction of task and organismic constraints dictates the nature of the information feedback required to facilitate the acquisition of skill. The augmented information available must match the degrees of freedom requiring constraint in the movement sequence.     

Generalization of error detection across motor tasks by men and women

One of the cornerstones of the human motor learning process is the ability to self-detect and self-correct movement errors. However, despite their importance, relatively little research has been done on these topics. One unanswered question is whether error detection is a general ability or one specific to the task to be learned. To investigate this issue, 66 college-age participants (49 women and 17 men) performed four motor learning tasks: an anticipation-timing task, a slow arm-positioning task, a rapid arm-movement task (400-msec. goal), and a tone-duration production task (400-msec. goal). 50 practice trials were provided on each task, 35 with knowledge of results (KR) and 15 without KR. Participants verbally estimated error on all trials before KR was given, except for the slow positioning task on which overall error in performance was the measure of error detection. Error detection was developed for each task but transfer of this ability only occurred when two tasks shared the same movement pattern. Men performed better on anticipation-timing than women, but men and women detected errors equally well on all tasks.     

Should Common Optimal Movement Patterns Be Identified as the Criterion to Be Achieved?

Recently, a new paradigm has been proposed for the study of knowledge of performance (Schmidt & Young, 1991). In this paradigm, the experimenters identified an optimal kinematic movement pattern, based on the performance of a best subject, which was imposed on all subjects as the criterion to achieve. This approach, which assumes that this pattern is the best way for all subjects to do the task, was tested in the present experiment. In Experiment 1, a common optimal movement pattern could not be identified by an analysis of scatterplot graphs of the scores plotted as a function of various kinematic vanables or by correlating (within and across subjects [N = 14]) each kinematic variable with the score. In Experiment 2, subjects (N = 12) were retrained in 2 separate sessions, during which they tried to reproduce either a personal best or the best subject's template. Results indicated that scores were similar regardless of the template pattern being used. During training, however, subjects who used their personal template had a lower incidence of zero scores and were more consistent than those who used the template of the best subject. This provided a second line of evidence against the assumption that a common optimal movement pattern exists for this type of task.     

Increased Sensitivity to Changes in Visual Feedback With Practice

In recent work investigating motor learning, the focus has been on the effect of modifying feedback at different levels of learning. Results suggest that learning is specific to the practiced conditions and that this specificity increases with practice. In a replication and extension of this previous work, 3 groups (N = 30 subjects) practiced a sequential positioning movement: Controls performed 300 trials with visually presented on-line kinematic feedback, whereas the other 2 groups, low practice (LP) or high practice (HP), performed, respectively, 50 or 300 trials without feedback. Pretest and posttest sessions of 10 trials each were performed with the on-line feedback. All groups improved with practice. It was apparent that the HP group exhibited more of a performance decrement in the postest than the LP group did, suggesting that motor learning is the process of forming an increasingly specific sensorimotor representation. These results have implications for motor learning paradigms, models of motor learning, and training.     

Social-comparative feedback affects motor skill learning

This study examined motivational effects of feedback on motor learning. Specifically, we investigated the influence of social-comparative feedback on the learning of a balance task (stabilometer). In addition to veridical feedback (error scores reflecting deviation from the target horizontal platform position) about their own performance after each trial, two groups received false normative information about the “average” score of others on that trial. Average performance scores indicated that the participant's performance was either above (better group) or below (worse group) the average, respectively. A control group received veridical feedback about trial performance without normative feedback. Learning as a function of social-comparative feedback was determined in a retention test without feedback, performed on a third day following two days of practice. Normative feedback affected the learning of the balance task: The better group demonstrated more effective balance performance than both the worse and control groups on the retention test. Furthermore, high-frequency/low-amplitude balance adjustments, indicative of more automatic control of movement, were greater in the better than in the worse group. The control group exhibited more limited learning and less automaticity than both the better and the worse groups. The findings indicate that positive normative feedback had a facilitatory effect on motor learning.     

Unique behavioral strategies in visuomotor learning: Hope for the non-learner

The existence of individual differences in motor learning capability is well known but the behaviors or strategies that contribute to this variability have been vastly understudied. What performance characteristics distinguish an expert level performer from individuals who experience little to no success, those labeled non-learners? We designed a rule-based visuomotor task which requires identification (discovery) and then exploitation of specific explicit and implicit task components that requires a specific movement pattern, the task rule, for goal achievement. When participants first attempt the task, they are informed about the goal, but are naïve to the task rule. Therefore, the purpose of this experiment is to determine how acquisition of both implicit and explicit task components, the inherent elements of the task rule, reveals differing strategies associated with performance and task success. We test the hypothesis that an examination of performance will reveal sub-groups with varying levels of success. Further, for each subgroup, we expect to find a unique relationship between visual Time-in-Target feedback (a measure of success) and subsequent updating of each task component. Out of 32 non-disabled adults, we identified three distinct sub-groups: (Low Performer/Non-Learner (LP, N = 9), Moderate Performer (MP, N = 12) and High Performer (HP, N = 11)). A quantitative analysis of behavioral patterns reveals three findings: First, the LP sub-group demonstrated significantly lower task success which was associated with difficulty identifying the explicit component of the task. Second, the HP sub-group acquired the two task components in parallel over practice. Third, when both explicit and implicit component performance is plotted across sub-groups, a task component continuum emerges that seamlessly progresses from low to moderate to high performer groups. An exploratory analysis reveals that self-reported level of prior lifetime accumulation of video game and physical activity experience is a significant predictor of individual task performance (R² = 0.50). In summary, what appears to be a key distinction between varying levels of human rule-based motor learning is the process by which feedback is used to update performance of inherent elements of the task rule. Evidence of a performance continuum and limited prior experience suggests that Low Performer/Non-Learners are generally inexperienced with these kinds of tasks, although the role of genetics and other innate learning capabilities in visuomotor learning is still largely unknown. These findings provoke new research directions toward probing the differential performance strategies associated with expertise and the development of interventions aimed to convert non-learners into learners.     

Cognitive load causes kinematic changes in both elite and non-elite rowers

The current motor literature suggests that extraneous cognitive load may affect performance and kinematics in a primary motor task. A common response to increased cognitive demand, as observed in past studies, might be to reduce movement complexity and revert to previously learned movement patterns, in line with the progression-regression hypothesis. However, according to several accounts of automaticity, motor experts should be able to cope with dual task demands without detriment to their performance and kinematics. To test this, we conducted an experiment asking elite and non-elite rowers to use a rowing ergometer under conditions of varying task load. We employed single-task conditions with low cognitive load (i.e., rowing only) and dual-task conditions with high cognitive load (i.e., rowing and solving arithmetic problems). The results of the cognitive load manipulations were mostly in line with our hypotheses. Overall, participants reduced movement complexity, for example by reverting towards tighter coupling of kinematic events, in their dual-task performance as compared to single-task performance. The between-group kinematic differences were less clear. In contradiction to our hypotheses, we found no significant interaction between skill level and cognitive load, suggesting that the rowers' kinematics were affected by cognitive load irrespective of skill level. Overall, our findings contradict several past findings and automaticity theories, and suggest that attentional resources are required for optimal sports performance.     

Neurobiological degeneracy: Supporting stability,flexibility and pluripotentiality in complex motor skill

This paper investigated neurobiological degeneracy of the motor system that emerged as a function of levels of environmental constraint. Fourteen participants performed a breaststroke-swimming task that required them to develop a specific biomechanically expert pattern and in turn provide the basis for a suitable task vehicle to study the functional role of movement variability. Inter-limb coordination was defined based on the computation of continuous relative phase between elbow and knee oscillators. Unsupervised cluster analysis on arm–leg coordination revealed the existence of different patterns of coordination when participants achieved the same task goal under different levels of environmental constraints (i.e. different amounts of forward resistances). In addition, clusters differed in terms of higher order derivatives (e.g., joint angular velocity, joint amplitude), suggesting an effective role for degeneracy in learning by allowing the exploration of the key relationships between motor organization and interacting constraints. There is evidence to suggest that neurobiological degeneracy supports the potential for motor re-organization to enhance motor learning.     

Influence of continual biofeedback on jaw pursuit-tracking in healthy adults and in adults with apraxia plus aphasia

Apraxia of speech (AOS) is a disorder of motor programming resulting from damage to premotor or anterior insula cortex. The authors used a pursuit visuomotor tracking task to test whether such a disorder interferes with development of motor programs or with modification of existing programs via integration of feedback. Healthy older adults (n = 15) and adults with AOS plus aphasia and nonverbal apraxia (n = 8) performed a jaw movement task with (a) continuous visual feedback of a target movement pattern and their jaw movement and (b) no feedback. Healthy speakers were more accurate and less variable with feedback, suggesting accurate development of a program and feedback integration. Apraxic individuals' performance accuracy and response to feedback suggested that the neurological damage impairs both development of new programs and efficient integration of feedback.