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.

Positive effects of blue light on motor coordination in older adults: A pilot study

PURPOSE

Falls are a risk factor for mortality in older adults. Lighting interventions can improve cognitive and motor task performance, but the effect on postural control with relevance to falling is unknown.

METHODS

Sixteen older adults participated in an intervention study with blue-enriched light delivered visually and/or transcranially for 12 min. Postural control in three conditions (60s eyes-open, dual-task, and eyes-closed), lower-limb motor coordination, and cognitive function were assessed.

RESULTS

Relative to placebo, visual blue-enriched light improved reaction time in the motor coordination task by 0.073 ± 0.035s (d = 0.77 ± 0.39; p = 0.003). Visual exposure decreased Area of Sway relative to the combined (d = 0.38 ± 0.26; p = 0.020) and placebo interventions (d = 0.47 ± 0.42; p = 0.067), with no significant effect on cognition.

CONCLUSION

Blue-enriched lighting demonstrates a novel approach to positively impact postural control and motor coordination in older adults. By impacting metrics associated with fall risk, light interventions may provide a clinical countermeasure to decrease the human costs of falls.

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.

Cortical, muscular, and kinetic activity underpinning attentional focus strategies during visuomotor control

Focusing internally on movement control or bodily sensations is frequently shown to disrupt the effectiveness and efficiency of motor control when compared to focusing externally on the outcome of movement. Whilst the behavioral consequences of these attentional strategies are well-documented, it is unclear how they are explained at the corticomuscular level. The aim of the present study was to investigate how attentional focus strategies affect kinetic, cortical, muscular, and corticomuscular activity during an isometric force precision task. In a repeated measures design, we measured force, EEG and EMG activity from twenty-seven participants who performed isometric contractions of the right hand whilst encouraged to adopt either an internal or external focus through a combination of instructions, secondary tasks, and self-report evaluations. Results indicated that focusing internally led to poorer force accuracy and steadiness compared to an external focus. An internal focus also increased muscle activity of the forearm flexor, increased EEG alpha activity across the parieto-occipital cortex, lowered frontal midline EEG theta activity, and lowered beta corticomuscular coherence between the forearm flexor and contralateral motor cortex. The results of this study provide a holistic understanding of how attentional focus strategies alter corticomuscular control during an isometric force precision task, paving the way for exploring how the behavioral consequences of attentional strategies can be explained at the corticomuscular levels across a wide range of motor tasks and contexts.

Soccer heading immediately alters brain function and brain-muscle communication

Introduction

There is growing evidence of a link between repetitive soccer heading and the increased incidence of neurodegenerative disease. Even a short bout of soccer heading has been shown to impair cognitive performance and disrupt movement control. However, a greater understanding of the mechanisms behind these immediate impairments is needed. The current study attempted to identify how a short bout of soccer heading alters brain function and brain-muscle communication during a movement task.

Methods

Sixty soccer players were exposed to either an acute bout (i.e., 20 balls thrown underarm) of soccer heading (n = 30) or a control condition where participants (n = 30) headed soccer balls in virtual reality (VR). Before and after heading, we measured cognitive performance on the King-Devick test, as well as electromyography (EMG), electroencephalography (EEG) and brain-muscle communication (i.e., corticomuscular coherence; CMC) during a force precision task.

Results

Following the heading protocol, the VR group improved their cognitive performance whereas the Heading group showed no change. Both groups displayed more precise force contractions at post-test. However, the VR group displayed elevated frontal theta activity and global increases in alpha and beta activity during the contraction task, whereas the Heading group did not. Contrary to our expectations, the Heading group displayed elevated CMC, whereas the VR group showed no change.

Discussion

Our findings indicate a short bout of soccer heading may impair cognitive function and disrupt the organization of efficient neural processes that typically accompany motor skill proficiency. Soccer heading also induced corticomuscular hyperconnectivity, which could represent compensatory brain-muscle communication and an inefficient allocation of increased task-related neuromuscular resources. These initial findings offer insights to the mechanisms behind the impairments experienced after a short bout of repetitive soccer heading.

A tool for measuring mental workload during prosthesis use: The Prosthesis Task Load Index (PROS-TLX)

When using a upper-limb prosthesis, mental, emotional, and physical effort is often experienced. These have been linked to high rates of device dissatisfaction and rejection. Therefore, understanding and quantifying the complex nature of workload experienced when using, or learning to use, a upper-limb prosthesis has practical and clinical importance for researchers and applied professionals. The aim of this paper was to design and validate a self-report measure of mental workload specific to prosthesis use (The Prosthesis Task Load Index; PROS-TLX) that encapsulates the array of mental, physical, and emotional demands often experienced by users of these devices. We first surveyed upper-limb prosthetic limb users who confirmed the importance of eight workload constructs taken from published literature and previous workload measures. These constructs were mental demands, physical demands, visual demands, conscious processing, frustration, situational stress, time pressure and device uncertainty. To validate the importance of these constructs during initial prosthesis learning, we then asked able-bodied participants to complete a coin-placement task using their anatomical hand and then using a myoelectric prosthesis simulator under low and high mental workload. As expected, using a prosthetic hand resulted in slower movements, more errors, and a greater tendency to visually fixate the hand (indexed using eye-tracking equipment). These changes in performance were accompanied by significant increases in PROS-TLX workload subscales. The scale was also found to have good convergent and divergent validity. Further work is required to validate whether the PROS-TLX can provide meaningful clinical insights to the workload experienced by clinical users of prosthetic devices.

A scoping review of the application of motor learning principles to optimize myoelectric prosthetic hand control

Although prosthetic hand rejection rates remain high, evidence suggests that effective training plays a major role in device acceptance. Receiving training early in the rehabilitation process also enhances functional prosthetic use, decreases the likelihood of developing an overreliance on the intact limb, and reduces amputation-related pain. Despite these obvious benefits, there is a current lack of evidence regarding the most effective training techniques to facilitate myoelectric prosthetic hand control, and it remains unknown whether training is effective in facilitating the acquisition and transfer of prosthetic skill. In this scoping review, we introduced and summarized key motor learning principles related to attentional focus, implicit motor learning, training eye-hand coordination, practice variability, motor imagery, and action observation, and virtual training and biofeedback. We then reviewed the existing literature that has applied these principles for training prosthetic hand control before outlining future avenues for further research. The importance of optimizing early and appropriate training cannot be overlooked. While the intuition and experience of clinicians holds enormous value, evidence-based guidelines based on well-established motor learning principles will also be crucial for training effective prosthetic hand control. While it is clear that more research is needed to form the basis of such guidelines, it is hoped that this review highlights the potential avenues for this work.

The effects of fatigued working memory functions on hypothesis testing during acquisition of a motor skill

Implicit motor learning paradigms aim to minimize verbal-analytical engagement in motor performance. Some paradigms do this by decreasing working memory activity during practice, which reduces explicit processes associated with the search for motor solutions (e.g., hypothesis testing). Here we designed a mentally demanding motor task to fatigue working memory prior to motor practice and then tested whether it reduced hypothesis testing. Fifty-nine participants were randomly assigned to complete the mentally demanding motor task (cognitive fatigue group) or to complete an undemanding motor task (nonfatigued control group). Feelings of fatigue, working memory functions, electroencephalography (EEG) Fz power, and vagal control were assessed pre- and posttask to quantify the effect of the mentally demanding motor task on cognitive fatigue. Thereafter, an adapted shuffleboard task was completed to determine the impact on hypothesis testing. Hypothesis testing was assessed by self-report, technique changes, and equipment-use solutions. Additionally, verbal-analytical engagement in motor performance was (indirectly) gauged with EEG T7-Fz connectivity and T7 power measures. Participants in the cognitive fatigue group reported more fatigue and displayed moderated working memory functions and Fz theta power. During practice of the shuffleboard task, participants also displayed more technique changes and higher verbal-analytical engagement in motor planning (EEG T7-Fz connectivity), compared with participants in the control group. The mentally demanding motor task suppressed working memory functions, but resulted in more, rather than less, hypothesis testing during shuffleboard practice. The implications are discussed in the context of implicit motor learning theory. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

The role of conscious processing of movements during balance by young and older adults

We examined the effect of verbalization of a phylogenetic motor skill, balance, in older and young adults with a low or a high propensity for conscious verbal engagement in their movements (reinvestment). Seventy-seven older adults and 53 young adults were categorized as high or low reinvestors, using the Movement Specific Reinvestment Scale, which assesses propensity for conscious processing of movements. Participants performed a pre- and post-test balance task that required quiet standing on a force-measuring plate. Prior to the post-test, participants described their pre-test balancing performance (verbalization) or listed animals (non-verbalization). Only young adults were affected by verbalization, with participants with a high propensity for reinvestment displaying increased medial-lateral entropy and participants with a low propensity for reinvestment displaying increased area of sway and medial-lateral sway variability following the intervention. The possible explanations for these results are discussed.

The influence of night-time electronic device use on subsequent sleep and propensity to be physically active the following day

This study investigated the effect of acute night-time blue-light exposure through electronic device use on sleep quality/quantity, exercise motivation and perceived exertion during exercise the following day. In a randomised, crossover design, 14 participants read a book on an iPad (light) or a hard-copy book (control) one hour before bedtime. Small but not significant differences in perceived sleep quality and quantity and measured sleep efficiency were found between light and control trials, suggesting that sleep may be negatively affected following one night of electronic device use. This did not impact motivation to exercise or perceived exertion during exercise the following day.

Falling for a Fake: The Role of Kinematic and Non-kinematic Information in Deception Detection

Kinematic and non-kinematic visual information have been examined in the context of movement anticipation by athletes, although less so in deception detection. This study examined the role of kinematic and non-kinematic visual information in the anticipation of deceptive and non-deceptive badminton shots. Skilled ( n = 12) and less skilled ( n = 12) badminton players anticipated the direction of deceptive and non-deceptive shots presented via video footage displayed in normal (kinematic and non-kinematic information), low (kinematic information emphasized), and high (non-kinematic information emphasized) spatial frequency conditions. Each shot was occluded one frame before shuttle-racquet contact or at contact. In deceptive trials, skilled players showed decreased anticipation accuracy in the high spatial frequency condition ( p = .050) compared to normal and low spatial frequency conditions, which did not differ. The study suggests that an emphasis on kinematic information results in accurate anticipation in response to deceptive movements and that an emphasis on non-kinematic information results in less accurate anticipation by experts.

Hunger hormone and sleep responses to the built-in blue-light filter on an electronic device: a pilot study

The aim of the current study was to investigate the effect of the blue-light filtering 'Night Shift' function on the Apple iPad at night and leptin production, perceived hunger levels and markers of sleep quality and quantity in healthy young adults. In a randomised, crossover design, 13 young adults (6 male/7 female) performed three experimental trials. Two of the interventions included one hour of night-time electronic device use; reading on an iPad ~30 cm from eyes, either with (iPad+NS) or without (iPad) the 'Night Shift' blue-light filtering feature turned on. The control trial involved reading a hard-copy book for one hour (CON). Leptin and perceived hunger and tiredness levels were assessed at various time points for the three experimental conditions. Objective sleep indices (actigraphy) and subjective ratings of sleep were recorded. There were no significant interactions for any of the measured variables (p > 0.05). Small to moderate effect sizes were found for perceived sleep quality, with CON (7.3 ± 1.7) having the highest value when compared to iPad+NS (6.6 ± 1.8, d = 0.29) and iPad (5.6 ± 2.3, d = 0.66). Moderate effects were associated with iPad+NS when compared to iPad (d = 0.77) and for iPad compared to CON (d = 0.90) for pre-post change in leptin concentration. Use of electronic devices at night may result in moderate suppression of leptin levels and impaired sleep quality, with negligible differences associated with whether or not the 'Night Shift' feature is turned on.

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.

Examining Movement-Specific Reinvestment and Performance in Demanding Contexts

Two experiments examined the roles of the dimensions of movement-specific reinvestment (movement self-consciousness and conscious motor processing) on performance under demanding conditions. In Experiment 1, novice golfers practiced a golf putting task and were tested under low- and high-anxiety conditions. Conscious motor processing was not associated with putting proficiency or movement variability; however, movement self-consciousness was positively associated with putting proficiency and appeared to be negatively associated with variability of impact velocity in low-anxiety conditions, but not in high-anxiety conditions. Increased anxiety and effort possibly left few attention resources for movement self-consciousness under high anxiety. In Experiment 2, participants performed a quiet standing task in single- and dual-task conditions. Movement self-consciousness was positively associated with performance when attention demands were low (single task) but not when attention demands were high (dual task). The findings provide insight into the differential influence of the two dimensions of movement-specific reinvestment under demanding conditions.

Acquiring visual information for locomotion by older adults: a systematic review

Developments in technology have facilitated quantitative examination of gaze behavior in relation to locomotion. The objective of this systematic review is to provide a critical evaluation of available evidence and to explore the role of gaze behavior among older adults during different forms of locomotion. Database searches were conducted to identify research papers that met the inclusion criteria of (1) study variables that included direct measurement of gaze and at least one form of locomotion, (2) participants who were older adults aged 60 years and above, and (3) reporting original research. Twenty-five papers related to walking on a straight path and turning (n=4), stair navigation (n=3), target negotiation and obstacle circumvention (n=13) and perturbation-evoked sudden loss of balance (n=5) were identified for the final quality assessment. The reviewed articles were found to have acceptable quality, with scores ranging from 47.06% to 94.12%. Overall, the current literature suggests that differences in gaze behavior during locomotion appear to change in late adulthood, especially with respect to transfer of gaze to and from a target, saccade-step latency, fixation durations on targets and viewing patterns. These changes appear to be particularly pronounced for older adults with high risk of falling and impaired executive functioning.

Individual reactions to stress predict performance during a critical aviation incident

BACKGROUND

Understanding the influence of stress on human performance is of theoretical and practical importance. An individual's reaction to stress predicts their subsequent performance; with a "challenge" response to stress leading to better performance than a "threat" response. However, this contention has not been tested in truly stressful environments with highly skilled individuals. Furthermore, the effect of challenge and threat responses on attentional control during visuomotor tasks is poorly understood.

DESIGN

Thus, this study aimed to examine individual reactions to stress and their influence on attentional control, among a cohort of commercial pilots performing a stressful flight assessment.

METHODS

Sixteen pilots performed an "engine failure on take-off" scenario, in a high-fidelity flight simulator. Reactions to stress were indexed via self-report; performance was assessed subjectively (flight instructor assessment) and objectively (simulator metrics); gaze behavior data were captured using a mobile eye tracker, and measures of attentional control were subsequently calculated (search rate, stimulus driven attention, and entropy).

RESULTS

Hierarchical regression analyses revealed that a threat response was associated with poorer performance and disrupted attentional control.

CONCLUSION

The findings add to previous research showing that individual reactions to stress influence performance and shed light on the processes through which stress influences performance.