Learning the invariants of a perceptual motor skill

The concept of invariant relative timing has typically been associated with the concept of a generalized motor programme. The present study approaches the phenomenon of invariant relative timing from the perspective of learning. The underlying question of concern for this study was, "What is learned." The specific question was whether relative timing is one of the essential properties of movement that is learned during skill acquisition. In the present experiment, subjects were given extensive practice in learning to track and reproduce a criterion waveform using a joystick control for their response. In order to test whether subjects learn the relative timing of a movement, they were transferred to tracking waveforms that were identical to the criterion in terms of relative timing, but different in terms of absolute timing. Measurements were taken on all waveforms in two conditions: (a) in a pursuit tracking condition where subjects were temporally constrained by the stimulus, and (b) in a reproduction condition where subjects' timing was not constrained. The outcome from both conditions gives support to the idea that humans learn invariant relative timing during the acquisition of a motor skill.     

Sensitivity of Smoothness Measures to Movement Duration,Amplitude, and Arrests

ABSTRACT

Studies of sensory-motor performance, including those concerned with changes because of age, disease, or therapeutic intervention, often use measures based on jerk, the time derivative of acceleration, to quantify smoothness and coordination. However, results have been mixed: some researchers report sensitive discrimination of subtle differences, whereas others fail to find significant differences even when they are obviously present. One reason for this is that different measures have been used with different scaling factors. These measures are sensitive to movement amplitude or duration to different degrees. The authors show that jerk-based measures with dimensions vary counterintuitively with movement smoothness, whereas a dimensionless jerk-based measure properly quantifies common deviations from smooth, coordinated movement.     

Effect of a 9-wk. after-school multiskills club on fundamental movement skill proficiency in 8- to 9-yr.-old children: an exploratory trial

This exploratory study examined the effects of a 9-wk. after-school multiskills club on fundamental movement skill proficiency in 8- to 9-yr.-old children. Two schools were randomly assigned to either a control (n = 15 children) or multiskill club (n = 19 children) condition. The multiskill club received 18 coaching sessions designed to improve fundamental movement skills. The control group followed normal routines. 7 skills were assessed using process-oriented measures with video analysis. Participation in the multiskill club yielded significant improvements in proficiency at posttest only in static balance, while potentially practically important improvements were observed in performance of the catch, throw, and kick skills. The after-school multiskill club offered a viable opportunity for movement skill acquisition, but any such programme would need to run for a longer duration to assess whether this type of activity could benefit all skills.     

Response timing variability: coherence of kinematic and EMG parameters

A detailed kinematic and electromyographic (EMG) analysis of single degree of freedom timing responses is reported to (a) determine the coherence of kinematic and EMG variability to the reduced timing error variability exhibited with amplitude increments within a given criterion movement time and (b) understand the temporal organization of various movement parameters in simple responses. The data reveal that the variability of kinematic (time to peak acceleration, duration of acceleration phase, time to peak deceleration) and EMG (duration of agonist burst, duration of antagonist burst, time to antagonist burst) timing parameters decreased with increments of average velocity in a manner consistent with the variable timing error. In addition, the coefficient of variation for peak acceleration, peak deceleration, and integrated EMG of the agonist burst followed the same trend. Increasing average movement velocity also led to decreases in premotor and motor reaction times. Overall, the findings suggest a strong coherence between the variability of response outcome, kinematic, and EMG parameters.     

Response Timing Variability

A detailed kinematic and electromyographic (EMG) analysis of single degree of freedom timing responses is reported to (a) determine the coherence of kinematic and EMG variability to the reduced timing error variability exhibited with amplitude increments within a given criterion movement time and (b) understand the temporal organization of various movement parameters in simple responses. The data reveal that the variability of kinematic (time to peak acceleration, duration of acceleration phase, time to peak deceleration) and EMG (duration of agonist burst, duration of antagonist burst, time to antagonist burst) timing parameters decreased with increments of average velocity in a manner consistent with the variable timing error. In addition, the coefficient of variation for peak acceleration, peak deceleration, and integrated EMG of the agonist burst followed the same trend. Increasing average movement velocity also led to decreases in premotor and motor reaction times. Overall, the findings suggest a strong coherence between the variability of response outcome, kinematic, and EMG parameters.     

The Role of Incentive Framing on Training and Transfer of Learning in a Visual Threat Detection Task

We examined the effects of different incentives on skill acquisition and transfer during threat detection in airline luggage screening. The incentives were presented within positive (gains) or negative (losses) frames, and points were given or taken away accordingly during training (with familiar targets) and transfer (to novel targets). During training, incentives exerted a more beneficial effect on skill acquisition than training without incentives. During transfer, incentives benefitted performance largely when presented as losses or penalties. Incentives framed as gains primed participants to say ‘yes’ more often leading to a high ratio of false positives; however, incentives framed as losses lead participants to become more selective in their ‘yes’ responses leading to a lower number of false positives but a comparable probability of correct detections. Interestingly, participants that received no training outperformed participants that received incentive‐based training, suggesting that incentives actually constrained rather than helped transfer of learning in this study. Copyright © 2011 John Wiley & Sons, Ltd.     

Quantitative measurement of handwriting in the assessment of drug-induced parkinsonism

Monitoring drug-induced side effects is especially important for patients who undergo treatment with antipsychotic medications, as these drugs often produce extrapyramidal side effects (EPS) resulting in movement abnormalities similar to parkinsonism. Scientists have developed several objective laboratory tests to measure and research drug-induced movement disorders, but equipment and tests are complex and costly and have not become accepted in large-scale, multi-site clinical trials. The goals of this study were to test whether a simple handwriting measure can discriminate between individuals with psychotropic-induced parkinsonism, Parkinson's disease, and healthy individuals, and to examine some of the psychometric properties of the measure. We examined pen movement kinematics during cursive writing of a standard word in 13 patients with idiopathic Parkinson's disease (PD), 10 schizophrenia patients with drug-induced parkinsonism (SZ), and 12 normal healthy control participants (NC). Participants were instructed to write the word "hello" in cursive twice, at three vertical height scales. Software was used for data acquisition and analysis of vertical stroke velocities, velocity scaling, and smoothness. There were four important results from this study: (1) both SZ patients with drug-induced EPS and PD participants exhibited impaired movement velocities and velocity scaling; (2) performance on the velocity scaling measure distinguished drug-induced EPS from normal with 90% accuracy; (3) SZ, but not PD participants displayed abnormalities in movement smoothness; and (4) there was a positive correlation between age and magnitude of the velocity scaling deficit in PD participants. This study demonstrates that kinematic analyses of pen movements during handwriting may be useful in detecting and monitoring subtle changes in motor control related to the adverse effects of psychotropic medications.     

The control of movement in the preferred and non-preferred hands

The nature of the difference in skill between the preferred and non-preferred hands was investigated using a peg-board task. The first experiment examined the effects of varying movement amplitude and target tolerance on performance. The difference between hands was found to be related to tolerance rather than movement amplitude. The second study analysed a film record of well-practised subjects, confirming the hypothesis that most of the difference between hands is due to relative slowness of the non-preferred hand in the positioning phase involving small corrective movements. Analysis of the type and number of errors further suggested that this result is not due to differences in duration of movements but to their increased frequency, implying greater accuracy of aiming with the preferred hand. Thus whilst the initial gross analysis implicated feedback processing in skill differences the more detailed analysis suggests that motor output of the nonpreferred hand is simply more variable.     

Whole-body kinematics and coordination in a complex dance sequence: Differences across skill levels

This study examined differences across skill levels in the kinematics of a complex, whole-body, asymmetrical, cyclical dance sequence, the ‘Alternate Basic’ in Cha-Cha-Cha, to determine whether observed differences were consistent with Bernstein's (1967) model of development of coordination. Bernstein proposed that with novel motor skills, beginners move their bodies rigidly and spastically, freezing kinematic degrees of freedom (DOF) to constrain the motor system. As the skill becomes practised, the DOF unfreeze and movements become more dynamic, allowing the integration of reactional elements (passive forces, moments, etc.) and organisation of more complex coordinative structures. Twenty-nine dancers - beginners (n = 10), intermediates (n = 10), experts (n = 9) - performed 12 cycles of the dance sequence (total duration ~60 s). Three-dimensional kinematic data from 36 joint angles were collected using a 14-camera infrared motion capture system. Most joints displayed increased amplitude and speed of movement, especially early in skill progression (beginner-intermediate stage), with no evidence of any decreases, showing that unfreezing occurred around the general movement pattern early. Speed of movement continued to increase later (intermediate-expert stage), as well as further unfreezing of the upper limbs. Changes to intra-limb couplings were limited, comprising some early reductions in coupling strength. Principal component analyses (PCA) showed that the structure of movement became more organised with increased skill. There was an early reduction in the number of coordinative structures, while later, movement was integrated more into the first coordinative structure. As predicted by Bernstein's coordination development model, therefore, the kinematic DOF unfroze as skill level progressed, leading to increased organisation of coordinative structures. The results of this study support the importance of a whole-body perspective in studies of coordination, with incorporation of kinetic variables in future research in order to examine the role that reactional elements play in motor skill development.     

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.     

The effects of ageing and cognitive impairment on on‐line and off‐line motor learning

Skilled performance is a collective function of practice‐related experiences (online learning) and post‐practice memory consolidation during sleep (offline learning). This study examines the effects of ageing and cognitive impairment on the on‐ and offline learning of a point‐to‐point arm movement. In a 3‐day experiment, older adults (cognitively normal or impaired) and young adults (YAs) were randomly assigned to practice or no‐practice conditions. Changes in the dependent measures of movement time and timing error were analysed within and between conditions across days. The findings suggest that both age and cognitive function affect skill learning. YAs improved performance via both on‐ and offline learning whereas older adults with normal cognitive capacities appeared to learn the movement skill primarily in an online mode. Cognitive impairments were found to hinder both types of skill learning. Implications for motor skill acquisition and rehabilitation are briefly discussed. Copyright © 2009 John Wiley & Sons, Ltd.     

Space-time invariance in handwriting: Contrasts between primary school children displaying advanced or retarded handwriting acquisition

Previous research into the handwriting of adult subjects has highlighted the possible roles of ‘relative timing’ (Viviani and Terzuolo 1980) and simple oscillations (Hollerbach 1981) in controlling movement. Both of these factors provide interesting perspectives with which to view the development of fine motor control in children. The spatio-temporal structure of writing movements was examined between children with refined handwriting skills and those exhibiting unusually poor writing for their age. The analysis concentrated on three sites of temporal variability: absolute timing, temporal patterning, and rhythmic content of the writing movements. The results supported the notion that the relative timing of segments within a movement sequence acts as a major constraint on motor output variability. It is suggested, however, that previous simplistic views of ‘relative timing’ be expanded, and that such timing may be dictated by optimisation strategies. Differences in the stability of the graphic product between groups could not be accounted for by differences in the rhythmic content of the movements. In the absolute timing of writing tasks, the results suggest that variability in writing time from trial to trial, and duration of intra-task pauses, are better indicators of writing difficulties than total writing time or the number of pauses.     

Individualized Challenge Point Practice as a Method to Aid Motor Sequence Learning

We conducted two studies to investigate if and how: (1) the rate of skill acquisition was related to motor performance at retention of a serial RT task (Study 1); and (2) whether rate of skill acquisition and baseline performance could be used to design schedules of practice related to contextual interference (CI) to enhance motor learning (Study 2). In Study 1, a slower rate of skill acquisition of repeating sequences in practice was related to faster response times at retention. Based on performance in Study 1, three levels of individualized CI were created for Study 2. Compared to low and moderate levels of CI, the higher CI practice condition led to faster response times in retention. We conclude that an individualized ‘challenge point’, which generates high CI enhances motor learning by optimizing challenge.     

Training for transfer of a movement timing skill

Previous findings by Langley and Zelaznik (1984) suggested two hypotheses why segmental (phasing) timing training produced a more superior transfer than nonsegmental (duration) timing training. One view (the higher order variable hypothesis) suggested that segmental training developed a timing skill that was flexible for various types of transfer tasks. Another view (the contextual interference hypothesis) was that the difficulty associated with segmental training was sufficient to provide this flexibility for later transfer. The present study contrasted these hypotheses by comparing transfer following phasing or duration training but which was low in contextual interference. The acquisition results favor a contextual interference explanation. The transfer results, however, are clearly a function of the development of a higher order timing skill. These findings are discussed in terms of the development of a timing skill that is best suited for flexibility of transfer.     

Fine and gross motor skills: The effects on skill-focused dual-tasks

Dual-task methodology often directs participants’ attention towards a gross motor skill involved in the execution of a skill, but researchers have not investigated the comparative effects of attention on fine motor skill tasks. Furthermore, there is limited information about participants’ subjective perception of workload with respect to task performance. To examine this, the current study administered the NASA-Task Load Index following a simulated shooting dual-task. The task required participants to stand 15 feet from a projector screen which depicted virtual targets and fire a modified Glock 17 handgun equipped with an infrared laser. Participants performed the primary shooting task alone (control), or were also instructed to focus their attention on a gross motor skill relevant to task execution (gross skill-focused) and a fine motor skill relevant to task execution (fine skill-focused). Results revealed that workload was significantly greater during the fine skill-focused task for both skill levels, but performance was only affected for the lesser-skilled participants. Shooting performance for the lesser-skilled participants was greater during the gross skill-focused condition compared to the fine skill-focused condition. Correlational analyses also demonstrated a significant negative relationship between shooting performance and workload during the gross skill-focused task for the higher-skilled participants. A discussion of the relationship between skill type, workload, skill level, and performance in dual-task paradigms is presented.     

Ecological validity of the German Bruininks-Oseretsky Test of Motor Proficiency – 2nd Edition

The diagnosis of Developmental Coordination Disorder (DCD) is based on poor motor coordination in the absence of other neurological disorders. In order to identify the presence of movement difficulties, a standardised motor assessment is recommended to determine the extent of movement problems which may contribute to deficits in daily task performance. A German version of the Bruininks-Oseretsky Test of Motor Proficiency, Second Edition (German BOT-2) was recently published. This study aimed to determine the ecological validity of the German BOT-2 by considering the relationship between assessment of fundamental motor skills with the BOT-2 and performance of everyday motor activities as evaluated by parents. This study used data obtained from the German BOT-2 standardisation study (n = 1.177). Subtests were compared with theoretically corresponding tasks via parental ratings of overall fine and gross motor abilities and performance in six typical motor activities. Non-parametric Jonckheere Terpstra test was used to identify differences in ordered contrasts. Subtests reflecting ‘Strength’, ‘Running Speed and Agility’, ‘Upper-Limb Coordination’, ‘Balance’, and ‘Fine Motor Precision’ were associated with parental evaluation of gross motor skills (p < 0.001). The subtest ‘Fine Motor Integration’ significantly correlated with parental ratings of females’ fine motor skills. Parental ratings of males’ fine motor skills were associated with three further subtests. Regarding everyday motor activities, the first three fine motor BOT-2 subtests were associated with parent evaluations of drawing, writing and arts and crafts (p < 0.001). Gross motor subtests of ‘Bilateral Coordination’ and ‘Balance’ showed no relationship to bike riding or performance in sports. Subtests of ‘Upper-Limb Coordination’ and ‘Strength’ showed significant correlations with sports, ball games and cycling. The results of this study suggest that the closer the proximity in the nature of the motor skills assessed in the German BOT-2 to daily motor tasks, the stronger the relationship between the clinical test and parental report of everyday performance of their child. The body functions tested in the German BOT-2, and hypothesized to underpin certain skills, were not automatically relevant for specific activities undertaken by German children. Future research should investigate the relationships of the various BOT-2 constructs for diagnosis of DCD.     

Learning complex upper-limb movements through practicing movement elements

Upper-limb complex movements constitute a major part of our daily activities. Research shows complex movements are generated by sequences of movement elements represented by a unimodal bell-shaped velocity curve. We utilized this understanding in the field of motor skill acquisition and hypothesized that practicing a movement element of a complex movement trajectory will facilitate the performance on the respective complex movement trajectory. To test this, we designed an experiment where the control group learned a full complex trajectory, whereas the two elemental groups learned two different movement elements of the complex trajectory. The two main outcome measures explaining the performance were accuracy and speed. The elemental groups, after training on movement elements, significantly improved their speed and accuracy when tested on the full complex trajectory. The result illustrated that training on a movement element of a complex trajectory benefited the performance of the full complex trajectory. The two elemental groups showed similar improvements in the performance of the complex motor skill, despite obtaining training on different movement elements of the same complex movement. The findings show that complex movements can be learned by practicing their movement elements.     

Effects of repetitive motor training on movement representations in adult squirrel monkeys: role of use versus learning

Current evidence indicates that repetitive motor behavior during motor learning paradigms can produce changes in representational organization in motor cortex. In a previous study, we trained adult squirrel monkeys on a repetitive motor task that required the retrieval of food pellets from a small-diameter well. It was found that training produced consistent task-related changes in movement representations in primary motor cortex (M1) in conjunction with the acquisition of a new motor skill. In the present study, we trained adult squirrel monkeys on a similar motor task that required pellet retrievals from a much larger diameter well. This large-well retrieval task was designed to produce repetitive use of a limited set of distal forelimb movements in the absence of motor skill acquisition. Motor activity levels, estimated by the total number of finger flexions performed during training, were matched between the two training groups. This experiment was intended to evaluate whether simple, repetitive motor activity alone is sufficient to produce representational plasticity in cortical motor maps. Detailed analysis of the motor behavior of the monkeys indicates that their retrieval behavior was highly successful and stereotypical throughout the training period, suggesting that no new motor skills were learned during the performance of the large-well retrieval task. Comparisons between pretraining and posttraining maps of M1 movement representations revealed no task-related changes in the cortical area devoted to individual distal forelimb movement representations. We conclude that repetitive motor activity alone does not produce functional reorganization of cortical maps. Instead, we propose that motor skill acquisition, or motor learning, is a prerequisite factor in driving representational plasticity in M1.     

Flow at work: An experience sampling approach

One of the core constructs of the positive psychology movement is that of ‘flow’, or optimal experience. The current study investigated the relationship between ‘flow’, the core job dimensions, and subjective well‐being (SWB), as well as distinguishing between the state and trait components of flow. Experience sampling methodology (ESM) was used to track 40 architectural students over a 15 week semester while they engaged in studio work. Hierarchical linear modelling (HLM) indicated that 74% of the variance in flow was attributable to situational characteristics compared to dispositional factors. Results also indicated that academic work that was high in skill variety and autonomy was associated with flow. Flow was found to be correlated with positive mood. Cross‐lagged regression analysis showed that momentary flow was predictive of momentary mood and not vice versa. The strengths and limitations of using ESM to study subjective work experiences and well‐being are discussed, as well as the implications of the study of flow or optimal experience for industrial/organizational psychology.     

Starting with the "right" foot minimizes sprint start time

Although asymmetries in hand and foot performance have been examined using a variety of movement tasks that require the fine control of the timing and amplitude of force generation, foot asymmetries in a functional gross motor movement task, such as the track and field sprint start, have yet to be examined. Twenty individuals (10 experienced, 10 inexperienced) were assessed for pedal asymmetries using the track and field sprint start. Each participant performed 48 starts (24 right foot starts and 24 left foot starts). The pattern of pedal asymmetries was consistent with that of manual asymmetries in that a left foot (i.e., left foot in rear position) reaction time advantage was found while there was a right foot (i.e., right foot in rear position) advantage for movement time and total response time (time from stimulus presentation until the end of the movement). These results are consistent with a right hemisphere specialization for spatio-temporal and attentional processes, and a left hemisphere specialization for movement execution.