Reduced influence of perceptual context in mild traumatic brain injury is not an illusion.

Perceptual grouping is impaired following mild traumatic brain injury (mTBI). This may affect visual size perception, a process influenced by perceptual grouping abilities. We conducted two experiments to evaluate visual size perception in people with self-reported history of mTBI, using two different size-contrast illusions: the Ebbinghaus Illusion (Experiment 1) and the Müller-Lyer illusion (Experiment 2). In Experiment 1, individuals with mTBI and healthy controls were asked to compare the size of two target circles that were either the same size or different sizes. The target circles appeared by themselves (no-context condition), or were surrounded by smaller or larger circles (context condition). Similar levels of accuracy were evident between the groups in the no-context condition. However, size judgements by mTBI participants were more accurate in the context condition, suggesting that they processed the target circles separately from the surrounding circles. In Experiment 2, individuals with mTBI and healthy controls judged the length of parallel lines that appeared with arrowheads (context condition) or without arrowheads (no context condition). Consistent with Experiment 1, size judgements by mTBI participants were more accurate than size judgements by control participants in the context condition. These findings suggest that mTBI influences size perception by impairing perceptual grouping of visual stimuli in near proximity.

Reinvestment in one versus one in-field and shoot-out field hockey performance.

The theory of reinvestment suggests that inappropriate use of attention to consciously engage in movements or decisions (movement specific reinvestment or decision specific reinvestment) can result in disrupted performance. We used moderation analysis to investigate the association between these forms of reinvestment and performance during one versus one in-field and shoot-out scenarios during field hockey. We expected that the propensity for reinvestment would be negatively associated with shoot-out performance but not in-field performance, because monitoring many other players during in-field play diverts attention away from conscious engagement in movements or decisions. No association was evident between decision specific reinvestment and in-field or shoot-out performance. However, a higher propensity for movement specific reinvestment (specifically, conscious motor processing) was negatively associated with shoot-out performance, but not in-field performance. We speculate that the necessity to shift between many non-static attentional demands during in-field situations may reduce capacity for movement specific reinvestment during performance.

Fundamental movement skills and balance of children with Down syndrome.

BACKGROUND: Conclusive evidence supports the importance of fundamental movement skills (FMS) proficiency in promoting physical activity and countering obesity. In children with Down Syndrome (DS), FMS development is delayed, which has been suggested to be associated with balance deficits. This study therefore examined the relationship between FMS proficiency and balance ability in children with DS, with the aim of contributing evidence to programmes that address FMS delay. METHODS: Participants consisted of 20 children with DS (7.1 ± 2.9 years old) and an age-matched control group of children with typical development (7.25 ± 2.5 years). In the first part of the study, FMS (i.e. locomotor and object control) proficiency of the children was tested using the Test of Gross Motor Development-2. Balance ability was assessed using a force platform to measure centre of pressure average velocity (AV; mm/sec), path length (mm), medio-lateral standard deviation (mm) and antero-posterior standard deviation (mm). In the second part of the study, children with DS participated in 5 weeks of FMS training. FMS proficiency and balance ability were tested post-training and compared to pre-training scores. Verbal and visuo-spatial short-term memory capacities were measured at pre-training to verify the role of working memory in skill learning. RESULTS: FMS proficiency was associated with centre of pressure parameters in children with DS but not in children with typical development. After controlling for age, AV was found to predict significant variance in locomotor (R2  = 0.61, P < 0.001) and object control (R2  = 0.69, P < 0.001) scores. FMS proficiency and mastery improved after FMS training, as did AV, path length and antero-posterior standard deviation (all P < 0.05). Verbal and visuo-spatial short-term memory did not interact with the effects of training. CONCLUSIONS: Children with DS who have better balance ability tend to have more proficient FMS. Skill-specific training improved not only FMS sub-skills but static balance stability as well. Working memory did not play a role in the changes caused by skills training. Future research should examine the causal relationship between balance and FMS.

Movement specific reinvestment and allocation of attention by older adults during walking.

Older repeat fallers have previously been shown to have a higher propensity to consciously monitor and control their movements (i.e. reinvestment) than non-fallers, yet to direct their attention equally between their limb movements and the external environment during locomotion (Wong et al. in J Am Geriatr Soc 57: 920-922, 2009). Whether increased attention to their movements is a result of falling or originates from a prior inclination to reinvest remains unclear. In order to better understand the interaction between reinvestment and attention during locomotion, this study examined the allocation of attention by older adults who had not fallen but displayed a high or low inclination for reinvestment. Twenty-eight low and twenty-eight high reinvestors were required to perform 30 walking trials. Their allocation of attention during walking was evaluated by asking tone-related attentional focus questions shortly after finishing each walking trial. High reinvestors were found to be more aware of their limb movements and less aware of the external environment. Low reinvestors, on the contrary, were more aware of the surrounding environment and less aware of their movement mechanics. Given that focusing internally to body movements has been proposed to utilise working memory capacity, the ability of high reinvestors to pick up all the environmental information necessary for successful locomotion might be compromised and requires further examination.

Refining the continuous tracking paradigm to investigate implicit motor learning.

In two experiments we investigated factors that undermine conclusions about implicit motor learning in the continuous tracking paradigm. In Experiment 1, we constructed a practice phase in which all three segments of the waveform pattern were random, in order to examine whether tracking performance decreased as a consequence of time spent on task. Tracking error was lower in the first segment than in the middle segment and lower in the middle segment than in the final segment, indicating that tracking performance decreased as a function of increasing time-on-task. In Experiment 2, the waveform pattern presented in the middle segment was identical in each trial of practice. In a retention test, tracking performance on the repeated segment was superior to tracking performance on the random segments of the waveform. Furthermore, substitution of the repeated pattern with a random pattern (in a transfer test) resulted in a significantly increased tracking error. These findings imply that characteristics of the repeated pattern were learned. Crucially, tests of pattern recognition implied that participants were not explicitly aware of the presence of a recurring segment of waveform. Recommendations for refining the continuous tracking paradigm for implicit learning research are proposed.

Reducing errors benefits the field-based learning of a fundamental movement skill in children.

Proficient fundamental movement skills (FMS) are believed to form the basis of more complex movement patterns in sports. This study examined the development of the FMS of overhand throwing in children through either an error-reduced (ER) or error-strewn (ES) training program. Students (n = 216), aged 8-12 years (M = 9.16, SD = 0.96), practiced overhand throwing in either a program that reduced errors during practice (ER) or one that was ES. ER program reduced errors by incrementally raising the task difficulty, while the ES program had an incremental lowering of task difficulty. Process-oriented assessment of throwing movement form (Test of Gross Motor Development-2) and product-oriented assessment of throwing accuracy (absolute error) were performed. Changes in performance were examined among children in the upper and lower quartiles of the pretest throwing accuracy scores. ER training participants showed greater gains in movement form and accuracy, and performed throwing more effectively with a concurrent secondary cognitive task. Movement form improved among girls, while throwing accuracy improved among children with low ability. Reduced performance errors in FMS training resulted in greater learning than a program that did not restrict errors. Reduced cognitive processing costs (effective dual-task performance) associated with such approach suggest its potential benefits for children with developmental conditions.

Reduction of errors during practice facilitates fundamental movement skill learning in children with intellectual disabilities.

BACKGROUND: Children with intellectual disabilities (ID) have been found to have inferior motor proficiencies in fundamental movement skills (FMS). This study examined the effects of training the FMS of overhand throwing by manipulating the amount of practice errors. METHODS: Participants included 39 children with ID aged 4-11 years who were allocated into either an error-reduced (ER) training programme or a more typical programme in which errors were frequent (error-strewn, ES). Throwing movement form, throwing accuracy, and throwing frequency during free play were evaluated. RESULTS: The ER programme improved movement form, and increased throwing activity during free play to a greater extent than the ES programme. Furthermore, ER learners were found to be capable of engaging in a secondary cognitive task while manifesting robust throwing accuracy performance. CONCLUSIONS: The findings support the use of movement skills training programmes that constrain practice errors in children with ID, suggesting that such approach results in improved performance and heightened movement engagement in free play.

Exploring the thresholds of vision for perception and action.

Based upon evidence that vision for action has quicker access to visual information than vision for perception, we hypothesized that the two systems may have differentiated visual thresholds. There is also evidence that, unlike vision for perception, vision for action is insensitive to cognitive dual-task interference. Using visual masking, we determined the visual thresholds of 15 participants in a perception task, an action task and an action plus concurrent cognitive secondary task. There was no difference in threshold between the perception task and the action task, but the action plus concurrent secondary task was accompanied by a greater visual threshold than both the perception task and the action task alone, indicating dual-task interference. The action task was thus most likely informed by vision for perception. The implications of these results are reviewed in the context of recent discussions of the two visual systems model.

Neural co-activation as a yardstick of implicit motor learning and the propensity for conscious control of movement.

Two studies examined EEG co-activation (coherence) between the verbal-analytical (T3) and motor planning (Fz) regions during a golf putting task. In Study 1, participants with a strong propensity to consciously monitor and control their movements, determined psychometrically by high scores on a movement specific Reinvestment Scale, displayed more alpha2 T3-Fz co-activation than participants with a weak propensity. In Study 2, participants who practiced a golf putting task implicitly (via an errorless learning protocol) displayed less alpha2 T3-Fz co-activation than those who practiced explicitly (by errorful learning). In addition, explicit but not implicit motor learners displayed more T3-Fz co-activation during golf putting under pressure, implying that verbal-analytical processing of putting movements increased under pressure. These findings provide neuropsychological evidence that supports claims that implicit motor learning can be used to limit movement specific reinvestment.

Probing the allocation of attention in implicit (motor) learning.

We investigated the attention demands associated with implicit and explicit (motor) learning and performance using a probe reaction time paradigm. Two groups of participants learned a golf putting task over eight blocks of 50 trials performed from different distances. One group (errorless learning) began putting from the shortest distance (25 cm) and moved progressively back to the furthest distance (200 cm). A second group (errorful learning) began putting from the furthest distance (200 cm) and moved progressively closer (25 cm). Retention tests were used to assess learning in the two conditions, followed by transfer tests in which participants used either an unusual putter or a very unusual putter. Transfer to the unusual putters had an equivalent effect on the performance of both errorless and errorful learners, but probe reaction times were unaffected in the errorless learners, suggesting that execution of their movements was associated with reduced attention demands. Reducing errors during initial learning trials may encourage an implicit mode of learning and lower the demand for cognitive resources in subsequent performance.

EEG activity during the verbal-cognitive stage of motor skill acquisition.

This study examined changes in EEG activity associated with motor performance during the verbal-cognitive stage of skill learning. Participants (n=14) were required to practice a sequential finger tapping task. EEG activity was recorded both before and after short-term practice, during finger tapping and during two control conditions. EEG power (Fz, Cz, Pz, T3, T4) and coherence (T3-Fz, T4-Fz, Fz-Cz, Fz-Pz) were computed for the theta (4-8 Hz), slow alpha (8-10 Hz), fast alpha (10-12 Hz), slow beta (12-20 Hz), and fast beta (20-28 Hz) bandwidths. Changes in motor performance were rapid during the very early stages of practice and then slowed in accord with the law of practice. These changes were accompanied by increases of theta power at Fz and beta coherence at T4-Fz, suggesting that progression through the verbal-cognitive stage of a sequential finger tapping task is accompanied by more narrowed attention and improved mapping between the stimuli and the finger movements.

Analogy versus explicit learning of a modified basketball shooting task: performance and kinematic outcomes.

The effects of differential instructional sets on motor skill acquisition were investigated using performance outcome and kinematic measures. Participants were provided with a single analogical instruction (analogy learning), a set of eight explicit (technical) instructions (explicit learning), or were not instructed (control). During a learning phase, participants (n=9 for each condition) performed a modified basketball shooting task over 3 days (160 trials per day). On the fourth day, participants performed a test phase consisting of two 40-trial retention tests, separated by a 40-trial secondary task transfer test, and completed a verbal protocol describing in detail the techniques that they had used to perform the task. No performance differences were found during the two retention tests, indicating similar amounts of learning for all groups. During the transfer test, performance deteriorated for both the explicit and control conditions, but not for the analogy condition. Participants in the analogy condition reported significantly fewer technical rules. Although no group differences were reported for kinematic variables, identification of movement components supported the claim that explicit learners exert conscious control over their movements, whereas analogy learners use a more implicit (unconscious or automatic) mode of movement control.

Reinvestment and movement disruption following stroke.

BACKGROUND: Disruption of the automaticity of movement execution is commonly experienced by people with stroke and may result from the person consciously attempting to control the mechanics of his or her movements. This act of turning one's attention in toward the mechanics of an action is referred to as "reinvestment." OBJECTIVES: This study aimed to explore the hypothesis that people with stroke have a greater propensity for reinvestment than the nondisabled population and to examine the relationship between reinvestment, functional impairment from stroke, and aspects of rehabilitation. METHODS: A cross-sectional questionnaire survey was used. A total of 148 people with stroke and 148 nondisabled adults completed the Movement Specific Reinvestment Scale. Correlational and multiple regression analyses were conducted to examine the relationship between functional impairment and various potential predictors. RESULTS: Compared with controls, people with stroke had a greater propensity for reinvestment. Conscious motor processing and time spent in rehabilitation were significant predictors of functional impairment following stroke. CONCLUSIONS: The association between functional impairment, propensity for reinvestment, and time spent in rehabilitation indicates that exclusive reliance on conscious motor processing strategies in the rehabilitation setting may be an impediment to regaining functional independence. There is a need to develop motor learning strategies for rehabilitation that restrain the propensity for reinvestment.

Trunk muscle training, posture fatigue, and performance in laparoscopic surgery.

PURPOSE: To investigate the effect of trunk muscle endurance training on the perception of back postural fatigue and performance of a laparoscopic task. MATERIALS AND METHODS: Thirty-one medical students (28 men and 13 women) with no laparoscopic surgical experience were randomly assigned to either a training group or a control group. Participants in the training group underwent a 6-week, 18-session trunk (abdominal and back muscle) endurance training program, whereas participants in the control group did not. Performance by all participants was assessed on a simulated laparoscopic task under varying conditions of low back postural fatigue, both before and after the training program. RESULTS: Participants in the training group showed significant improvements in trunk endurance after the 6-week, trunk endurance training program (P<0.05), whereas those in the control group did not. The improvements in trunk endurance were accompanied by significantly reduced perceptions of discomfort (P< .001) and fewer errors during performance of the laparoscopic task. (P<0.02), whereas no significant changes occurred for the control group (P>0.05). CONCLUSION: Increasing trunk endurance can increase postural fatigue and discomfort during simulated laparoscopic tasks, which may assist in the management of errors during laparoscopy.

Implicit motor learning and complex decision making in time-constrained environments.

The cost-effectiveness of the implicit (procedural) knowledge that supports motor expertise enables surprisingly efficient performance when a decision and an action must occur in close temporal proximity. The authors argue that if novices learn the motor component of performance implicitly rather than explicitly, then they will also be efficient when they make a decision and execute an action in close temporal proximity. Participants (N = 35) learned a table tennis shot implicitly or explicitly. The authors assessed participants' motor performance and movement kinematics under conditions that required a concurrent low-complexity decision or a concurrent high-complexity decision about where to direct each shot. Performance was disrupted only for participants who learned explicitly when they made high-complexity decisions but not when they made low-complexity decisions. The authors conclude that implicit motor learning encourages cognitively efficient motor control more than does explicit motor learning, which allows performance to remain stable when time constraints call for a complex decision in tandem with a motor action.

Reinvestment and falls in community-dwelling older adults.

BACKGROUND: Falls are common in older adults and have many adverse consequences. In an attempt to prevent further incidents, elder fallers may consciously monitor and control their movements. Ironically, conscious movement control may be one factor that contributes to disruption of automaticity of walking, increasing the likelihood of subsequent falls. OBJECTIVE: The Movement Specific Reinvestment Scale (MSRS), which aims to measure the propensity for movement-related self-consciousness and for conscious processing of movement, was used to try to discriminate elder fallers from non-fallers. METHODS: Fifty-two volunteer older adults, aged 65 or above, participated. In addition to the 10-item MSRS, participants completed the Mini-Mental State Examination questionnaire, Timed "Up & Go" test, and Four Word Short-Term Memory test. Demographics including age, gender, and history of falling were collected. RESULTS: Elder fallers scored significantly higher than non-fallers on both the movement self-consciousness and conscious motor processing components of the MSRS. Logistic regression revealed a significant association between the MSRS (conscious motor processing component) and "faller or non-faller" status. CONCLUSIONS: Elder fallers may have a higher propensity to consciously control their movements. The MSRS shows potential as a clinical tool with which to predict falls in the elderly, as well as to gain insight into the perception of safety during walking in any impaired patient.

Stable implicit motor processes despite aerobic locomotor fatigue.

Implicit processes almost certainly preceded explicit processes in our evolutionary history, so they are likely to be more resistant to disruption according to the principles of evolutionary biology [Reber, A. S. (1992). The cognitive unconscious: An evolutionary perspective. Consciousness and Cognition, 1, 93-133.]. Previous work (e.g., [Masters, R. S. W. (1992). Knowledge, (k)nerves and know-how: The role of explicit versus implicit knowledge in the breakdown of a complex motor skill under pressure. British Journal of Psychology, 83, 343-358.]) has shown that implicitly learned motor skills remain stable under psychological pressure and concurrent cognitive demands, and recently [Poolton, J. M., Masters, R. S. W., & Maxwell, J. P. (2007). Passing thoughts on the evolutionary stability of implicit motor behaviour: Performance retention under physiological fatigue. Consciousness and Cognition, 16(2), 456-468.] showed that they also remain stable under conditions of anaerobic fatigue that would have significantly challenged the survival skills of our ancestors. Here we examine the stability of an implicitly learned motor skill under fatigue conditions that primarily tax a different physiological system (the aerobic system), but which have equally strong evolutionary connotations. Participants acquired a throwing task by means of an errorless (implicit) learning method or an errorful (explicit) method. Motor performance in the errorless condition, but not the errorful condition, remained stable following an exhaustive VO2 max. running test. Our findings replicate and extend the work of Poolton et al., providing further support for Reber's evolutionary distinction between implicit and explicit processes.

Implicit motor learning in surgery: implications for multi-tasking.

BACKGROUND: Implicitly learned motor skills are characterized by minimal conscious knowledge of the movements involved and stable performance despite stress, fatigue, or multi-tasking. In contrast, explicitly learned motor skills are characterized by conscious knowledge of the movements and performance that tends to be less stable under stress, fatigue, and multi-tasking. We examined the acquisition of a basic surgical skill in three observational learning treatment conditions designed to accomplish implicit or explicit motor learning. We then tested performance in conditions that emulated multi-tasking in the operating theater. Our intention was to elaborate current understanding of implicit and explicit processes that underpin observational learning in the surgical environment. METHODS: Thirty-six novice adults were assigned randomly to an observation-only, an instructed-observation, or a guided-observation treatment condition, in which they learned to perform a suturing and knot-tying task in a Learning Phase. Their performance during multi-tasking was then assessed objectively by motion analysis during a Test Phase. RESULTS: In the Learning Phase, performance improved equally in the treatment conditions throughout learning, with participants using fewer hand movements and completing the task more quickly. Participants in the observation-only and the guided-observation treatment condition, however, reported significantly less movement-related knowledge than participants in the instructed-observation condition. In the Test Phase, participants in the instructed-observation condition exhibited slower completion times and more hand movements when they were required to multi-task, whereas in the observation-only and the guided-observation treatment condition, participants showed stable performance. CONCLUSIONS: A surgical skill that is learned by observation alone or by observation accompanied by guidance to reduce the number of errors that are committed tends to be learned implicitly and to have stable performance during multi-tasking. The efficacy of observation for acquiring technical skills implies that, at least for some skills, verbal instructions may not be necessary.

Implicit sequence learning processes after unilateral stroke.

Implicit learning is durable over time, robust under psychological stress and shows specificity of transfer; characteristics that may be beneficial in stroke rehabilitation. The purpose of this study was to investigate implicit sequence learning processes in unilateral stroke using an extended number of trial blocks in a serial reaction time task (SRTT). Previous research, using a SRTT, has produced equivocal results that may be associated with the small number of trial blocks used. Seven adults, at least one year after stroke, and eight controls performed 54 blocks of a modified SRTT over two weeks. Participants responded with a finger key press during acquisition and retention and with a whole arm movement during transfer. Response times in milliseconds were used to measure learning. The stroke group performed more slowly than the controls during all experimental phases. Response times for both groups decreased with practice of the repeating sequence, increased with introduction of a random sequence, and decreased when reintroduced to the repeating sequence of the SRTT. Both groups demonstrated delayed retention of knowledge of the sequence over a two-week period and exhibited specificity of transfer. These data suggest that with extended practice people with unilateral stroke are able to learn implicitly.