Action Boundary Proximity Effects on Perceptual-Motor Judgments

INTRODUCTION: Designed as a more ecological measure of reaction times, the Perception-Action Coupling Task (PACT) has shown good reliability and within-subject stability. However, a lengthy testing period was required. Perceptual-motor judgments are known to be affected by proximity of the stimulus to the action boundary. The current study sought to determine the effects of action boundary proximity on PACT performance, and whether redundant levels of stimuli, eliciting similar responses, can be eliminated to shorten the PACT.METHODS: There were 9 men and 7 women who completed 4 testing sessions, consisting of 3 familiarization cycles and 6 testing cycles of the PACT. For the PACT, subjects made judgments on whether a series of balls presented on a tablet afford "posting" (can fit) through a series of apertures. There were 8 ratios of ball to aperture size (B-AR) presented, ranging from 0.2 to 1.8, with each ratio appearing 12 times (12 trials) per cycle. Reaction times and judgment accuracy were calculated, and averaged across all B-ARs. Ratios and individual trials within each B-AR were systematically eliminated. Variables were re-averaged, and intraclass correlation coefficients (ICC) and coefficients of variation (CVTE) were calculated in an iterative manner.RESULTS: With elimination of the 0.2 and 1.8 B-ARs, the PACT showed good reliability (ICC = 0.81-0.99) and consistent within-subject stability (CVTE = 2.2-14.7%). Reliability (ICC = 0.81-0.97) and stability (CVTE = 2.6-15.6%) were unaffected with elimination of up to 8 trials from each B-AR.DISCUSSION: The shortened PACT resulted in an almost 50% reduction in total familiarization/testing time required, significantly increasing usability.Johnson CD, LaGoy AD, Pepping G-J, Eagle SR, Beethe AZ, Bower JL, Alfano CA, Simpson RJ, Connaboy C. Action boundary proximity effects on perceptual-motor judgments. Aerosp Med Hum Perform. 2019; 90(12):1000-1008

Impact of Increased Load Carriage Magnitude on the Dynamic Postural Stability of Men and Women

The impact of load carriage on dynamic postural stability affects the survivability of the Warfighter by influencing performance capabilities and injury incidence. Further, sex may interact with the relationship between load carriage and dynamic postural stability to further compromise survivability. PURPOSE: To investigate the effect of load carriage magnitude on dynamic postural stability of men and women and its relationship to jumping ability. METHODS: 32 subjects (16 men, 16 women) were investigated for maximum jump height and dynamic postural stability. Dynamic postural stability was assessed by subjects jumping a horizontal distance of 40% their height over a 30cm hurdle, landing on one leg on a force plate (sample rate = 1200 Hz). 3 trials were completed for 3 load conditions: +0, +20 and +30% body weight (BW). Dynamic postural stability was determined from ground reaction force data during landings, by calculation of the dynamic postural stability index (DPSI). Maximum jump height was assessed by subjects performing 3 countermovement jumps (sample rate = 1000 Hz). Two-way repeated measures ANOVA were used to compare mean DPSI scores between sexes and conditions (α = 0.05). Pearson’s Correlation Coefficients were used to determine the relationship between jump height and change in DPSI scores between conditions (α = 0.05). RESULTS: Load condition significantly affected DPSI (F = 100.304, p = 0.001). DPSI scores increased between the 0% (0.359 ± 0.041), 20% (0.396 ± 0.034) and 30% (0.420 ± 0.028) BW load conditions. No significant effect of sex on DPSI was found (F = 0.131). No significant sex by load interaction on DPSI was found (F = 0.393). No significant correlations were found between jump height and change in DPSI scores between conditions. CONCLUSION: Increased load was found to negatively affect dynamic postural stability, most likely as a result of modifying the demands of the task. Therefore, the dynamic postural stability of men and women changes comparably in response to increased load carriage magnitude. Future research should focus on the effects of load on dynamic postural stability under higher loads and during more military-specific tasks

Intersession Reliability and Within-Session Stability of a Novel Perception-Action Coupling Task

BACKGROUND: The perception-action coupling task (PACT) was designed as a more ecologically valid measure of alertness/reaction times compared to currently used measures by aerospace researchers. The purpose of this study was to assess the reliability, within-subject variability, and systematic bias associated with the PACT. METHODS: There were 16 subjects (men/women = 9/7; age = 27.8 +/- 3.6 yr) who completed 4 identical testing sessions. The PACT requires subjects to make judgements on whether a virtual ball could fit into an aperture. For each session, subjects completed nine cycles of the PACT, with each cycle lasting 5 min. Judgement accuracy and reaction time parameters were calculated for each cycle. Systematic bias was assessed with repeated-measures ANOVA, reliability with intraclass correlation coefficients (ICC), and within-subject variability with coefficients of variation (CVTE). RESULTS: Initiation time (Mean = 0.1065 s) showed the largest systematic bias, requiring the elimination of three cycles to reduce bias, with all other variables requiring, at the most, one. All variables showed acceptable reliability (ICC > 0.70) and within-subject variability (CVTE <20%) with only one cycle after elimination of the first three cycles. CONCLUSIONS: With a three-cycle familiarization period, the PACT was found to be reliable and stable

Cruisin' for a Snoozin': the role of sleep in resilience to simulated military operational stress

BACKGROUND: Military personnel must maintain high levels of operational performance despite exposure to sleep loss, caloric restriction, physical exertion and high cognitive loads. These operational stressors may influence sleep, operational performance and perception-action coupling performance. Sleep prior to exposure to operational stressors may mitigate the effects of such stressors. PURPOSE: 1) Examine trait-like aspects of sleep parameters across exposure to simulated military operational stress (SMOS); 2) Examine the impact of baseline sleep on operationally-relevant performance outcomes; 3) Examine the effects of SMOS on perception-action coupling; 4) Examine different aspects of neurobehavioral resilience and differences in baseline sleep between resilient and vulnerable participants METHODS: 69 active-duty and reserve status military personnel completed a 5-day SMOS protocol that included two days of sleep restriction and disruption. Participants completed assessments of subjective alertness, vigilance, perception-action coupling, marksmanship and physical performance throughout the protocol. 1) Intra-class correlations across different sleep opportunities were calculated for EEG sleep parameters. 2) Habitual and baseline sleep parameters were regressed on marksmanship and physical performance outcomes. 3) Effects of SMOS and time-of-day on perception-action coupling were examined. 4) Participants were classified as resilient or vulnerable using a 2-step decision-making approach that included performance during sleep disruption and change in performance from baseline of different neurobehavioral (alertness, vigilance and perception-action coupling) assessments. RESULTS: 1) Absolute spectral activity during non-rapid eye movement sleep was stable and robust across variable sleep opportunities during the SMOS protocol (ICC > .6). 2) Baseline aerobic fitness, daytime sleepiness and slow wave activity predicted physical performance but not marksmanship. 3) Perception-action coupling was maintained during typical waking hours (18:00 and 22:00) but deteriorated across days at 04:00. 4) Subjective measures of alertness, and behavioral measures of vigilance and perception-action coupling reflect distinct aspects of neurobehavioral resilience. CONCLUSION: Individual differences in sleep are maintained across exposure to SMOS, demonstrating the trait-like nature of sleep. Differences in baseline sleep may have implications for operationally-relevant aspects of physical performance and for neurobehavioral resilience. Lastly, perception-action coupling performance is sensitive to the combined effects of SMOS and time-of-day and reflects a distinct aspect of performance from vigilance

Establishing and applying measurement reliability in perceptual-motor coordination tasks

Over a large body of literature focused on perceptual-motor coordination for action-based affordance tasks, little regard has been given for measurement reliability. The purpose of this paper was to outline this issue and provide an example reliability study for a measure of an individual’s ability to perceive action opportunities for leaping. Ten participants completed three testing sessions, each consisting of 24 trials of the task. Reaction times and accuracy of perceptual responses were calculated. Analysis of variance was used to test for systematic mean changes. Intraclass correlation coefficients (ICCs) and coefficients of variation (CV) were used to quantify intersession agreement and within-subject variability. With the removal of six trials for familiarization, acceptable agreement (ICC= 0.930) and within-subject variability (CV= 9.5%) were established, using six further testing trials. Overall, this paper provides the rationale and simple methods for addressing measurement reliability in perceptual-motor coordination research

Increased Risk of Musculoskeletal Injury Following Sport-Related Concussion: A Perception–Action Coupling Approach

Recent studies have concluded that athletes have increased risk of musculoskeletal injury following sport-related concussion. While an underlying explanation is still unknown, perceptual-motor control may be implicated in this increased risk. Some authors have purported that indirect perception (i.e., a “top-down” view of neuromuscular control) may be disrupted following sport-related concussion. Direct perception theory states that the athlete and environment are inextricably linked in a continuous perception–action coupling loop. That is, the athlete is able to directly perceive opportunities for action (e.g., “affordances”) in the environment. Based on these notions, the aim of the current paper was to introduce a theoretical model that argues that sport-related concussion may dysregulate the direct perception process, potentially increasing behavioral risk of musculoskeletal injury during sport. Our model is integrated with a sport-related concussion clinical treatment model, which highlights individualized profiles that characterize the heterogeneous response to sport-related concussion. These profiles have a typical constellation of symptoms (e.g., anxiety, fatigue, ocular dysfunction, etc.), which themselves have been associated with disrupted perception–action coupling, independent of sport-related concussion. Therefore, we argue that athletes who have not re-established perception–action coupling loops following sport-related concussion may be at increased risk of subsequent musculoskeletal injury

Natural Oscillatory Frequency Slowing in the Premotor Cortex of Early-Course Schizophrenia Patients: A TMS-EEG Study

Despite the heavy burden of schizophrenia, research on biomarkers associated with its early course is still ongoing. Single-pulse Transcranial Magnetic Stimulation coupled with electroencephalography (TMS-EEG) has revealed that the main oscillatory frequency (or “natural frequency”) is reduced in several frontal brain areas, including the premotor cortex, of chronic patients with schizophrenia. However, no study has explored the natural frequency at the beginning of illness. Here, we used TMS-EEG to probe the intrinsic oscillatory properties of the left premotor cortex in early-course schizophrenia patients (<2 years from onset) and age/gender-matched healthy comparison subjects (HCs). State-of-the-art real-time monitoring of EEG responses to TMS and noise-masking procedures were employed to ensure data quality. We found that the natural frequency of the premotor cortex was significantly reduced in early-course schizophrenia compared to HCs. No correlation was found between the natural frequency and age, clinical symptom severity, or dose of antipsychotic medications at the time of TMS-EEG. This finding extends to early-course schizophrenia previous evidence in chronic patients and supports the hypothesis of a deficit in frontal cortical synchronization as a core mechanism underlying this disorder. Future work should further explore the putative role of frontal natural frequencies as early pathophysiological biomarkers for schizophrenia

Cognitive performance during prolonged periods in isolated, confined, and extreme environments

Background Astronauts are required to perform a variety of cognitively demanding tasks in the face of multiple prolonged stressors in isolated, confined and extreme (ICE) environments. Short-term ICE environmental exposure can negatively affect cognitive performance, alter emotional responses, and increase reaction time in affordance-based tasks; however, these domains have not been studied simultaneously in prolonged ICE settings. Coastal and Inland Antarctic stations are excellent analogs for spaceflight based on overlapping environmental features such as limited external communication and confinement in extreme conditions. Our purpose was to investigate the effects of 5-month ICE environment analogs, and co-occurring emotional responses, on cognitive performance and affordance perception. Methods Participants assigned to either Inland or Coastal stations completed the Psychomotor Vigilance Test (PVT), Spaceflight Cognitive Assessment Tool for Windows (WinSCAT), Perception-Action Coupling Task (PACT), and Mental Health Checklist (MHCL) each month for five consecutive months. A series of 1-way ANOVAs were conducted to evaluate WinSCAT, PVT, and PACT performance across time. A series of backward stepwise linear regressions were conducted to determine if duration of ICE environment exposure (months 1–5), station (Coastal and Inland), gender (male and female), education (college degree and no degree), and time of day, in addition to Positive Adaptation, Poor Self-Regulation, and Anxious Apprehension MHCL subscales, were related to cognitive performance outcomes, including WinSCAT composite, PVT median reaction time and lapses, and PACT accuracy and lapses. Results A within-subjects’ effect indicated improvements across WinSCAT composite score, PACT Accuracy, and PACT lapses. Final regression models were significant across all outcomes, and indicate an improvement in WinSCAT and PACT performance during the winter over, assigned station and education level marginally contributed to the observed variance in cognitive performance. Conclusion Sustained attention, cognitive performance, and affordance perception and actualization outcomes were marginally affected, or improved, during a prolonged ICE environmental exposure

Differences in affordance-based behaviors within an isolated and confined environment are related to sleep, emotional health and physiological parameters

Astronauts are required to operate within isolated, confined and extreme environments (ICE). Isolated, confined and controlled (ICC) environments, such as the NASA Human Exploration Research Analog (HERA) site, provide ways of studying and predicting behavioral changes that occur in response to prolonged exposure to ICE environments. An important aspect of behavior is affordance perception. An affordance refers to a possibility for action. Affordance perception and related behavior may be affected by sleep, emotional health and stress. The inability to accurately perceive changes in affordances may increase the risk adopted during a task, possibly compromising mission success. Purpose: Investigate changes in affordance perception during a 30-day exposure to an ICC environment and investigate the relationship between affordance perception and sleep, emotional health and physiological markers of stress. Methods: Sixteen subjects completed five sessions of the perception-action coupling task (PACT), a novel tablet-based affordance perception task, on days 3, 10, 17, 24 and 5-days post-mission. The 15-min PACT presents a series of virtual balls and apertures varying in ball to aperture size ratio (B-AR) from 0.2 to 1.8. Subjects determined whether the ball could fit through the aperture and responded based on their perception of this action possibility. Participants also completed an emotional health questionnaire, the Mental Health Checklist (MHCL) throughout the mission. Actigraphy was used to collect sleep measures. Multiple ANOVA were conducted to assess changes in PACT response time (RT), accuracy (ACC) and lapses across time and to assess the role of individual differences in sleep, MHCL measures and salivary biomarkers of stress on performance. Results: A significant main effect of time was observed on PACT RT (F4, 60 = 3.631, p =.010, n2p =.195) which was faster on day 24 (0.738 ± 0.088s) than day 17 (0.768 ± 0.092s). No differences were observed between other timepoints. ACC and lapses did not vary during the mission (p >.05). Individual differences in sleep duration, sleep efficiency, MHCL measures and salivary biomarkers related to individual differences in aspects of PACT performance. Conclusion: Modest changes in PACT performance were observed during a 30-day ICC exposure. Individual differences in performance may relate to individual differences in sleep and emotional health

Shared and distinct abnormalities in sleep-wake patterns and their relationship with the negative symptoms of Schizophrenia Spectrum Disorder patients

Sleep and rest-activity-rhythm (RAR) abnormalities are commonly reported in schizophrenia spectrum disorder (SSD) patients. However, an in-depth characterization of sleep/RAR alterations in SSD, including patients in different treatment settings, and the relationship between these alterations and SSD clinical features (e.g., negative symptoms) is lacking. SSD (N = 137 altogether, N = 79 residential and N = 58 outpatients) and healthy control (HC) subjects (N = 113) were recruited for the DiAPAson project. Participants wore an ActiGraph for seven consecutive days to monitor habitual sleep-RAR patterns. Sleep/rest duration, activity (i.e., M10, calculated on the 10 most active hours), rhythm fragmentation within days (i.e., intra-daily variability, IV; beta, steepness of rest-active changes), and rhythm regularity across days (i.e., inter-daily stability, IS) were computed in each study participant. Negative symptoms were assessed in SSD patients with the Brief Negative Symptom Scale (BNSS). Both SSD groups showed lower M10 and longer sleep/rest duration vs. HC, while only residential patients had more fragmented and irregular rhythms than HC. Compared to outpatients, residential patients had lower M10 and higher beta, IV and IS. Furthermore, residential patients had worse BNSS scores relative to outpatients, and higher IS contributed to between-group differences in BNSS score severity. Altogether, residentials and outpatients SSD had both shared and unique abnormalities in Sleep/RAR measures vs. HC and relative to one another, which also contributed to the patients' negative symptom severity. Future work will help establish whether improving some of these measures may ameliorate the quality of life and clinical symptoms of SSD patients