A Sensorimotor Basis for Motor Learning: Evidence Indicating Specificity of Practice

Our previous work (Proteau, Marteniuk, Girouard, & Dugas, 1987) was concerned with determining whether with relatively extensive practice on a movement aiming task, as the skill theoretically starts becoming open-loop, there would be evidence for a decreasing emphasis on visual feedback for motor control. We eliminated vision of the moving limb after moderate and extensive practice and found that the movement became more dependent on this feedback with greater amounts of practice. In the present study, we wished to test the hypothesis, developed from our previous work, that at the base of movement learning is a sensorimotor representation that consists of integrated information from central processes and sensory feedback derived from previous experiences on the movement task. A strong test of this hypothesis would be the prediction that for an aiming task, the addition of vision, after moderate and relatively extensive practice without vision, would lead to an increasingly large movement decrement, relative to appropriate controls. We found good support for this prediction. From these and previous results, and the idea of the sensorimotor representation underlying learning, we develop the idea that learning is specific to the conditions that prevail during skill acquisition. This has implications for the ideas of generalized motor program and schema theory.     

Specificity of practice, visual information, and intersegmental dynamics in rapid-aiming limb movements

The authors tested the specificity of practice hypothesis on intersegmental dynamics of rapid-aiming limb movements. During acquisition, 20 participants performed an aiming task as quickly and accurately as possible either with or without vision. Following moderate (140 trials) and extensive (560 trials) practice, participants completed 20 transfer test trials in a no-vision condition. Overall, the acquisition-phase findings revealed that vision improved aiming accuracy performance but had only a slight impact on movement time and intersegmental dynamics. After 560 trials of practice, however, withdrawal of vision resulted in specificity of practice effects on intersegmental dynamics at the shoulder as well as on aiming accuracy. Taken together, those findings support and extend the specificity of practice hypothesis     

Development of Multiple Movement Representations With Practice: Specificity Versus Flexibility

The question addressed in the present experiment was whether an individual who practices a task under different conditions of afferent information develops different movement representations, each of which is based on the most accurate source of afferent information for movement control. In Experiment 1, participants (N = 23) performed a manual aiming movement in a target-only condition for 520 trials before performing in a normal vision condition for an equivalent amount of practice. Control groups performed all practice trials in either a normal vision or a target-only condition. The results revealed that the movement representation developed in the initial (target-only) practice phase remained accessible for movement planning and control. The results of Experiment 2 indicated, however, that participants did not maintain such a representation when their initial practice in the target-only condition was reduced (40 or 160 trials) before they had extensive practice in normal vision. Those results indicate that extensive practice in a target-only and then in a normal vision condition enables an individual to plan and control his or her movement on the basis of the most efficient source of available afferent information. Because visual afferent information provides optimal information for ensuring movement accuracy, however, if initial practice in the target-only condition is only modest or moderate it is likely that that information source will progressively dominate all other sources of afferent information for movement planning and control.     

Development of multiple movement representations with practice: specificity versus flexibility

The question addressed in the present experiment was whether an individual who practices a task under different conditions of afferent information develops different movement representations, each of which is based on the most accurate source of afferent information for movement control. In Experiment 1, participants (N = 23) performed a manual aiming movement in a target-only condition for 520 trials before performing in a normal vision condition for an equivalent amount of practice. Control groups performed all practice trials in either a normal vision or a target-only condition. The results revealed that the movement representation developed in the initial (target-only) practice phase remained accessible for movement planning and control. The results of Experiment 2 indicated, however, that participants did not maintain such a representation when their initial practice in the target-only condition was reduced (40 or 160 trials) before they had extensive practice in normal vision. Those results indicate that extensive practice in a target-only and then in a normal vision condition enables an individual to plan and control his or her movement on the basis of the most efficient source of available afferent information. Because visual afferent information provides optimal information for ensuring movement accuracy, however, if initial practice in the target-only condition is only modest or moderate it is likely that that information source will progressively dominate all other sources of afferent information for movement planning and control.     

Using Dual Tasks to Test Immediate Transfer of Training Between Naturalistic Movements: A Proof-of-Principle Study

Theories of motor learning predict that training a movement reduces the amount of attention needed for its performance (i.e., more automatic). If training one movement transfers, then the amount of attention needed for performing a second movement should also be reduced, as measured under dual task conditions. The authors’ purpose was to test whether dual task paradigms are feasible for detecting transfer of training between two naturalistic movements. Immediately following motor training, subjects improved performance of a second untrained movement under single and dual task conditions. Subjects with no training did not. Improved performance in the untrained movement was likely due to transfer, and suggests that dual tasks may be feasible for detecting transfer between naturalistic actions.     

Role of action observation and action in sequence learning and coding

A complex sequence learning task was used to determine if the type of coding acquired through physical practice (PP), observation of the stimulus (Obs-S), or observation of stimulus and action (Obs-SA) differs between conditions and whether the type of observation influences subsequent learning of the task when physical practice was permitted. Participants in the Obs-S group were permitted to watch the sequentially illuminated stimuli on the screen. In the Obs-SA group participants could see both flexion-extension movements of the model's arm performing the sequence and the sequentially illuminated stimuli on the screen. Participants in the PP group actually performed the 16-element sequence with their dominant right arm. Delayed retention tests and two inter-manual transfer tests were completed following each of two acquisition sessions. First, the data indicated that learning the sequence structure, as revealed by response time per element, occurred similarly irrespective of the initial practice condition. Secondly, the movement sequence appeared to be coded in abstract visual-spatial coordinates resulting in effector-independent performance. Finally, observing the model's action and sequential stimuli allows participants to transfer the perceived aspects of the movement sequence into efficient coordination patterns when additional physical practice is permitted.     

Training for the production of novel timing movements: Contextual considerations

Summary The present study represented an attempt to determine the extent to which transfer performance on a novel timing task is influenced by contextual similarity (i.e., similar instructions, task requirements, etc.) between training and transfer phases of performance. All subjects were given trials on a task which involved a linear ballistic arm movement. The length of the movement was defined as the distance between a start button and a hinged target, which was knocked over by the subject at the end of the response. During training subjects attempted to produce their movements in a time of 550 ms and were given knowledge of results regarding timing error after each trial. During transfer trials a 300 ms movement time was attempted and no knowledge of results was given. Context was defined by the number of different movement distances performed during training and transfer. Half of the subjects received training trials with a single distance (constant context) while the other half received an equal number of trials with each of three distances (varied context). During the transfer stage of the experiment, subjects either performed in the same movement distance context experienced during training (i.e., constant to constant; varied to varied) or in the opposite context (i.e., constant to varied; varied to constant). The results of the transfer analysis suggested that similariy of context between training and transfer phases of performance was not crucial to the accurate production of a novel closed-timing movement. Implications of the present results for recent theories of memory development are discussed.     

Blocking Perturbations and Multilimb Control in Rapid-Aiming Movements

The effect of an unexpected mechanical block on the control of multilimbaiming movements was studied in two experiments. In the first experiment, subjects (N = 10) attempted to push two hand levers 9 cm forward in 200 ms without vision. In the second experiment, subjects (N = 9) attempted to push hand levers and foot pedals forward 9 cm in 200 ms. After a practice period, five attempts at blocking the limb movements were made on the left lever and the right lever (Experiment 1) and on both levers (Experiment 2 only) during randomly selected trials. When one hand was blocked in Experiment 1, the other hand undershot the target on the first blocked trial, with slight reductions in movement time. When one hand was blocked in Experiment 2, the contralateral limb undershot the target on all blocked trials, but this had little effect on the lower limbs. The lower limbs undershot the target when both up- per limbs were blocked. Discrete movement corrections were made on more of the blocked trials relative to the unblocked control trials. Interlimb correlations decreased following the block, suggesting that subjects dissociated the limbs in an effort to minimize the effect of the block.     

Gradual training reduces practice difficulty while preserving motor learning of a novel locomotor task

Motor learning strategies that increase practice difficulty and the size of movement errors are thought to facilitate motor learning. In contrast to this, gradual training minimizes movement errors and reduces practice difficulty by incrementally introducing task requirements, yet remains as effective as sudden training and its large movement errors for learning novel reaching tasks. While attractive as a locomotor rehabilitation strategy, it remains unknown whether the efficacy of gradual training extends to learning locomotor tasks and their unique requirements. The influence of gradual vs. sudden training on learning a locomotor task, asymmetric split belt treadmill walking, was examined by assessing whole body sagittal plane kinematics during 24 hour retention and transfer performance following either gradual or sudden training. Despite less difficult and less specific practice for the gradual cohort on day 1, gradual training resulted in equivalent motor learning of the novel locomotor task as sudden training when assessed by retention and transfer a day later. This suggests that large movement errors and increased practice difficulty may not be necessary for learning novel locomotor tasks. Further, gradual training may present a viable locomotor rehabilitation strategy avoiding large movement errors that could limit or impair improvements in locomotor performance.     

Optimizing the Use of Vision in Manual Aiming: The Role of Practice

The purpose of this study was to determine how subjects learn to adjust the characteristics of their manual aiming movements in order to make optimal use of the visual information and reduce movement error. Subjects practised aiming (120 trials) with visual information available for either 400 msec or 600 msec. Following acquisition, they were transferred to conditions in which visual information was available for either more or less time. Over acquisition, subjects appeared to reduce target-aiming error by moving to the target area more quickly in order to make greater use of vision when in the vicinity of the target. With practice, there was also a reduction in the number of modifications in the movement. After transfer, both performance and kinematic data indicated that the time for which visual information was available was a more important predictor of aiming error than the similarity between training and transfer conditions. These findings are not consistent with a strong “specificity of learning” position. They also suggest that, if some sort of general representation or motor programme develops with practice, that representation includes rules or procedures for the utilization of visual feedback to allow for the on-line adjustment of the goal-directed movement.     

Afferent Information for Motor Control: The Role of Visual Information in Different Portions of the Movement

The question addressed in the present study was whether subjects (N = 24) can use visual information about their hand, in the first half of an aiming movement, to ensure optimal directional accuracy of their aiming movements. Four groups of subjects practiced an aiming task in either a complete vision condition, a no-vision condition, or in a condition in which their hand was visible for the first half [initial vision condition (IV)] or the second half of the movement [final vision condition (FV)]. Following 240 trials of acquisition, all subjects were submitted to a transfer test that consisted of 40 trials performed in a no-vision condition. The results indicated that seeing the hand early in movement did not help subjects to optimize either directional or amplitude accuracy. On the other hand, when subjects viewed their hand closer to the target, movements resulted that were as accurate as those performed under a complete vision condition. In transfer, withdrawing vision did not cause any increase in aiming error for the IV or the no-vision conditions. These results replicated those of Carlton (1981) and extended those of Bard and colleagues (Bard, Hay, & Fleury, 1985) in that they indicated that the kinetic visual channel hypothesized by Paillard (1980; Paillard & Amblard, 1985) appeared to be inoperative beyond 40deg of visual angle.     

The effect of type of practice on motor learning in children

The present investigation was concerned with the variability-of-practice hypothesis of Schmidt's schema theory of motor learning; i. e. it was sought to determine if there is an optimal way to structure the variable practice session with regard to schema formation. Furthermore, children's motor recognition (movement evaluation) was examined, in addition to recall (movement production), since apparently no such studies had been done within the context of schema theory before. Eighty-eight girls and boys with a mean age of 11.3 years were tested on a throwing task. Three groups of subjects practised under variable conditions (different target distances and weights) that differed with regard to contextual interference and sequential organization of task variations; another group received constant throwing practice. Following practice trials with knowledge of results, the four treatment groups and a control group without prior practice were required to produce and evaluate a novel response (novel target distance and weight) without vision and knowledge of results. The results supported the variability-of-practice hypothesis, in that variable practice in general facilitated recall and recognition on the novel task. Furthermore, variable practice with the highest level of contextual interference (random order of tasks) produced most effective transfer performance, suggesting that the structure of the variable-practice session in fact plays a role with regard to the effectiveness of motor schema development. Contrary to the ‘organization hypothesis’ (Gentile and Nacson, 1976) a hierarchical organization of movement variations was not more beneficial to schema formation than random practice.     

Effects of Practice Conditions and Supplemental Training Method on Cognitive Learning and Interpersonal Skill Generalization

Organizational expenditures for interpersonal-skills training have been rising. However, little is known about the translation of cognitive learning into skilled interpersonal-task performance, or about the mechanisms through which interpersonal skills in one domain generalize to other interpersonal tasks. This study used a 2 × 2 experimental design to examine the effectiveness of neutral versus stressful practice conditions and mastery-versus performance-oriented supplemental training for improving cognitive learning and interpersonal-skill transfer to a novel task. Participants who experienced stressful salary-negotiation practice conditions, followed by mastery-oriented supplemental training, showed greater skill transfer when performing a novel task (i.e., contract negotiations). Results showed that superior cognitive learning (i.e., recall, comprehension, and synthesis) and greater time on task were the mechanisms that supported interpersonal-skill transfer for trainees in the stressful practice/ mastery-oriented training condition when compared with the other experimental groups.     

Organization and learning of visual-motor information during different orders of limb movement: step, velocity, acceleration

Theoretical use of the tracking paradigm as a means of understanding perceptual-motor organization has been influenced by ambiguous assumptions concerning the relation of time orders of force production to the learning and performance of time orders of limb movement. This study provides both a conceptual framework for clarifying these assumptions, and empirical data for testing them. The independent variables were (a) target motion (step, velocity, acceleration); (b) stick loading (elasticity, damping, mass); and (c) practice. The dependent variables were absolute terror for step and time-integrated squared error for velocity and acceleration. The hypothesis was that proficiency of tracking is inversely related to mathematical complexity of reactive forces, within constraints imposed by familiarity with required types of transfer functions. Five subjects were assigned to track one type of target motion in each of the three loading conditions, respectively. Cursor-present "training" trials were alternated with cursor-absent "test" trials. Thereby, a premium was placed on attention to proprioceptive feedback, at least at the start of training. The hypothesis could not be rejected.     

Development of interception of moving targets by chimpanzees (<Emphasis Type="Italic">Pan troglodytes</Emphasis>) in an automated task

The experiments investigated how two adult captive chimpanzees learned to navigate in an automated interception task. They had to capture a visual target that moved predictably on a touch monitor. The aim of the study was to determine the learning stages that led to an efficient strategy of intercepting the target. The chimpanzees had prior training in moving a finger on a touch monitor and were exposed to the interception task without any explicit training. With a finger the subject could move a small "ball" at any speed on the screen toward a visual target that moved at a fixed speed either back and forth in a linear path or around the edge of the screen in a rectangular pattern. Initial ball and target locations varied from trial to trial. The subjects received a small fruit reinforcement when they hit the target with the ball. The speed of target movement was increased across training stages up to 38 cm/s. Learning progressed from merely chasing the target to intercepting the target by moving the ball to a point on the screen that coincided with arrival of the target at that point. Performance improvement consisted of reduction in redundancy of the movement path and reduction in the time to target interception. Analysis of the finger's movement path showed that the subjects anticipated the target's movement even before it began to move. Thus, the subjects learned to use the target's initial resting location at trial onset as a predictive signal for where the target would later be when it began moving. During probe trials, where the target unpredictably remained stationary throughout the trial, the subjects first moved the ball in anticipation of expected target movement and then corrected the movement to steer the ball to the resting target. Anticipatory ball movement in probe trials with novel ball and target locations (tested for one subject) showed generalized interception beyond the trained ball and target locations. The experiments illustrate in a laboratory setting the development of a highly complex and adaptive motor performance that resembles navigational skills seen in natural settings where predators intercept the path of moving prey. Electronic Supplementary Material Supplementary material is available for this article if you access the article at . A link in the frame on the left on that page takes you directly to the supplementary material.     

Can Video Self-Modeling Improve Affected Limb Reach and Grasp Ability in Stroke Patients?

The authors examined whether feedforward video self-modeling (FF VSM) would improve control over the affected limb, movement self-confidence, movement self-consciousness, and well-being in 18 stroke survivors. Participants completed a cup transport task and 2 questionnaires related to psychological processes pre- and postintervention. Pretest video footage of the unaffected limb performing the task was edited to create a best-of or mirror-reversed training DVD, creating the illusion that patients were performing proficiently with the affected limb. The training yielded significant improvements for the forward movement of the affected limb compared to the unaffected limb. Significant improvements were also seen in movement self-confidence, movement self-consciousness, and well-being. FF VSM appears to be a viable way to improve motor ability in populations with movement disorders.     

Effects of type of responding on memory/visual search: Responding just “yes” or just “no” can lead to inflexible performance

Interactions of stimulus consistency and type of responding were examined during perceptual learning. Subjects performed hybrid memory-visual search tasks over extended consistent and varied mapping practice. Response conditions required subjects to respond to both the presence and absence of a target, only when a target was present or only when a target was not present. After training, the subjects were transferred to a different response condition. The results indicate that: (1) performance on search tasks with stimuli that are variably mapped show no qualitative changes attributable to manipulation of response format; (2) improvement due to consistent mapping (CM) practice is attenuated in the no-only response condition; (3) yes-only CM training attenuates the subjects ability to transfer to no-only responding; and (4) yes/no CM training leads to the greatest improvement and transfer when compared with other responding conditions. The practice and transfer data support and extend previous research investigating effects of response set in memory/visual search and help to delineate factors that facilitate or inhibit reduction of load effects in memory and visual search.     

Rapid aimed limb movements: differential effects of practice on component submovements

Three experiments are reported in which subjects practiced rapid aimed limb movements (arm pointing and wrist rotation) toward a visible target region. Subjects were required to minimize their movement durations while still landing in the target. The movement trajectories were examined to assess the effects of practice on separate component submovements of the limb movements. The results revealed that practice improved primarily temporal, not spatial, aspects of performance. Practice reduced the overall movement durations, but had different effects on the individual submovements. Practice allowed subjects to reduce the amount of time spent performing final corrective submovements, but actually increased slightly the time needed to produce the initial ballistic submovement. The results suggest that practice in the present task primarily enhanced the ability to use feedback information, but there was also some evidence of changes in the ballistic, preprogrammed portion of the movements. The results demonstrate that analysis of submovements can reveal important details of the underlying motor control processes.     

Rapid Aimed Limb Movements: Differential Effects of Practice on Component Submovements

Three experiments are reported in which subjects practiced rapid aimed limb movements (arm pointing and wrist rotation) toward a visible target region. Subjects were required to minimize their movement durations while still landing in the target. The movement trajectories were examined to assess the effects of practice on separate component submovements of the limb movements. The results revealed that practice improved primarily temporal, not spatial, aspects of performance. Practice reduced the overall movement durations, but had different effects on the individual submovements: Practice allowed subjects to reduce the amount of time spent performing final corrective submovements, but actually increased slightly the time needed to produce the initial ballistic submovement. The results suggest that practice in the present task primarily enhanced the ability to use feedback information, but there was also some evidence of changes in the ballistic, preprogrammed portion of the movements. The results demonstrate that analysis of submovements can reveal important details of the underlying motor control processes.     

A secondary task is not always costly: Context‐based guidance of visual search survives interference from a demanding working memory task

Repeatedly encountering a visual search display with the target located at a fixed position relative to the distractors facilitates target detection, relative to novel displays – which is attributed to search guidance by (acquired) long‐term memory (LTM) of the distractor ‘context’ of the target. Previous research has shown that this ‘contextual cueing’ effect is severely impeded during learning when participants have to perform a demanding spatial working memory (WM) task concurrently with the search task, though it does become manifest when the WM task is removed. This has led to the proposal that search guidance by LT context memories critically depends on spatial WM to become ‘expressed’ in behaviour. On this background, this study, of two experiments, asked: (1) Would contextual cueing eventually emerge under dual‐task learning conditions if the practice on the task(s) is extended beyond the short training implemented in previous studies? and given sufficient practice, (2) Would performing the search under dual‐task conditions actually lead to an increased cueing effect compared to performing the visual search task alone? The answer is affirmative to both questions. In particular, Experiment 1 showed that a robust contextual cueing effect emerges within 360–720 dual‐task trials as compared to some 240 single‐task trials. Further, Experiment 2 showed that when dual‐ and single‐task conditions are performed in alternating trials blocks, the cueing effect for the very same set of repeated displays is significantly larger in dual‐task blocks than in single‐task blocks. This pattern of effects suggests that dual‐task practice eventually leads to direct, or ‘automatic’, guidance of visual search by learnt spatial LTM representations, bypassing WM processes. These processes are normally engaged in single‐task performance might actually interfere with direct LTM‐based search guidance.