Perceptual learning across saccades: Feature but not location specific.

Perceptual learning is the ability to enhance perception through practice. The hallmark of perceptual learning is its specificity for the trained location and stimulus features, such as orientation. For example, training in discriminating a grating's orientation improves performance only at the trained location but not in other untrained locations. Perceptual learning has mostly been studied using stimuli presented briefly while observers maintained gaze at one location. However, in everyday life, stimuli are actively explored through eye movements, which results in successive projections of the same stimulus at different retinal locations. Here, we studied perceptual learning of orientation discrimination across saccades. Observers were trained to saccade to a peripheral grating and to discriminate its orientation change that occurred during the saccade. The results showed that training led to transsaccadic perceptual learning (TPL) and performance improvements which did not generalize to an untrained orientation. Remarkably, however, for the trained orientation, we found a complete transfer of TPL to the untrained location in the opposite hemifield suggesting high flexibility of reference frame encoding in TPL. Three control experiments in which participants were trained without saccades did not show such transfer, confirming that the location transfer was contingent upon eye movements. Moreover, performance at the trained location, but not at the untrained location, was also improved in an untrained fixation task. Our results suggest that TPL has both, a location-specific component that occurs before the eye movement and a saccade-related component that involves location generalization.

Visual softness perception can be manipulated through exploratory procedures.

Both visual and haptic softness perception have recently been shown to have multiple dimensions, such as deformability, granularity, fluidity, surface softness, and roughness. During haptic exploration, people adjust their hand motions (exploratory procedures, EPs) based on the material qualities of the object and the particular information they intend to acquire. Some of these EPs are also shown to be associated with perceived softness dimensions, for example, stroking a silk blouse or applying pressure to a pillow. Here, we aimed to investigate whether we can manipulate observers' judgments about softness attributes through exposure to videos of others performing various EPs on everyday soft materials. In two experiments, participants watched two videos of the same material: one with a corresponding EP and the other without correspondence; then, they judged these materials based on 12 softness-related adjectives (semantic differentiation method). The results of the second experiment suggested that when the EP is congruent with the dimension from which the material is chosen, the ratings for the adjectives from the same dimension are higher than the incongruent EP. This study provides evidence that participants can assess material properties from optic and mechanical cues without needing haptic signals. Additionally, our findings indicate that manipulating the hand motion can selectively facilitate material-related judgments.

Do Simulated Augmented Reality Overlays Influence Street-Crossing Decisions for Non-Mobility-Impaired Older and Younger Adult Pedestrians?

OBJECTIVE: This study used a virtual environment to examine how older and younger pedestrians responded to simulated augmented reality (AR) overlays that indicated the crossability of gaps in a continuous stream of traffic. BACKGROUND: Older adults represent a vulnerable group of pedestrians. AR has the potential to make the task of street-crossing safer and easier for older adults. METHOD: We used an immersive virtual environment to conduct a study with age group and condition as between-subjects factors. In the control condition, older and younger participants crossed a continuous stream of traffic without simulated AR overlays. In the AR condition, older and younger participants crossed with simulated AR overlays signaling whether gaps between vehicles were safe or unsafe to cross. Participants were subsequently interviewed about their experience. RESULTS: We found that participants were more selective in their crossing decisions and took safer gaps in the AR condition as compared to the control condition. Older adult participants also reported reduced mental and physical demand in the AR condition compared to the control condition. CONCLUSION: AR overlays that display the crossability of gaps between vehicles have the potential to make street-crossing safer and easier for older adults. Additional research is needed in more complex real-world scenarios to further examine how AR overlays impact pedestrian behavior. APPLICATION: With rapid advances in autonomous vehicle and vehicle-to-pedestrian communication technologies, it is critical to study how pedestrians can be better supported. Our research provides key insights for ways to improve pedestrian safety applications using emerging technologies like AR.

Bound by Experience: Updating the Body Representation When Using Virtual Objects.

OBJECTIVE: Four web-based experiments investigated flexibility of disembodiment of a virtual object that is no longer actively controlled. Emphasis was on possibilities to modify the timescale of this process. BACKGROUND: Interactions with virtual objects are commonplace in settings like teleoperation, rehabilitation, and computer-aided design. These objects are quickly integrated into the operator's body schema (embodiment). Less is known about how long such embodiment lasts. Understanding the dynamics of this process is crucial because different applied settings either profit from fast or slow disembodiment. METHOD: To induce embodiment, participants moved a 2D virtual hand through operating a computer mouse or touchpad. After initial embodiment, participants either stopped or continued moving for a fixed period of time. Embodiment ratings were collected continuously during each trial. RESULTS: Results across all experiments indicated that embodiment for the virtual hand gradually increased during active use and gradually decreased after stopping to use it. Disembodiment unfolded nearly twice as fast as embodiment and showed a curved decay pattern. These dynamics remained unaffected by anticipation of active control that would be required in an upcoming task. CONCLUSION: The results highlight the importance of continuously experiencing active control in virtual interactions if aiming at inducing stable embodiment of a virtual object. APPLICATION: Our findings suggest that applications of virtual disembodiment such as virtual tools or interventions to affect a person's body representation critically depend on continuous updating of sensorimotor experience. However, if switching between virtual objects, for example, during teleoperation or video gaming, after-effects are unlikely to affect performance.

Quantifying accuracy on distance estimation tasks: A Monte Carlo study.

An important aspect of perceptual learning involves understanding how well individuals can perceive distances, sizes, and time-to-contact. Oftentimes, the primary goal in these experiments is to assess participants' errors (i.e., how accurately participants perform these tasks). However, the manner in which researchers have quantified error, or task accuracy, has varied. The use of different measures of task accuracy, to include error scores, ratios, and raw estimates, indicates that the interpretation of findings depends on the measure of task accuracy utilized. In an effort to better understand this issue, we used a Monte Carlo simulation to evaluate five dependent measures of accuracy: raw distance judgments, a ratio of true to estimated distance judgments, relative error, signed error, and absolute error. We simulated data consistent with prior findings in the distance perception literature and evaluated how findings and interpretations vary as a function of the measure of accuracy used. We found there to be differences in both statistical findings (e.g., overall model fit, mean square error, Type I error rate) and the interpretations of those findings. The costs and benefits of utilizing each accuracy measure for quantifying accuracy in distance estimation studies are discussed.

Perception-Action Integration Is Altered in Functional Movement Disorders.

BACKGROUND: Although functional neurological movement disorders (FMD) are characterized by motor symptoms, sensory processing has also been shown to be disturbed. However, how the integration of perception and motor processes, essential for the control of goal-directed behavior, is altered in patients with FMD is less clear. A detailed investigation of these processes is crucial to foster a better understanding of the pathophysiology of FMD and can systematically be achieved in the framework of the theory of event coding (TEC). OBJECTIVE: The aim was to investigate perception-action integration processes on a behavioral and neurophysiological level in patients with FMD. METHODS: A total of 21 patients and 21 controls were investigated with a TEC-related task, including concomitant electroencephalogram (EEG) recording. We focused on EEG correlates established to reflect perception-action integration processes. Temporal decomposition allowed to distinguish between EEG codes reflecting sensory (S-cluster), motor (R-cluster), and integrated sensory-motor processing (C-cluster). We also applied source localization analyses. RESULTS: Behaviorally, patients revealed stronger binding between perception and action, as evidenced by difficulties in reconfiguring previously established stimulus-response associations. Such hyperbinding was paralleled by a modulation of neuronal activity clusters, including reduced C-cluster modulations of the inferior parietal cortex and altered R-cluster modulations in the inferior frontal gyrus. Correlations of these modulations with symptom severity were also evident. CONCLUSIONS: Our study shows that FMD is characterized by altered integration of sensory information with motor processes. Relations between clinical severity and both behavioral performance and neurophysiological abnormalities indicate that perception-action integration processes are central and a promising concept for the understanding of FMD. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Using a haptic dynamic clamp to reduce arousal: preference, arousal, and coordination stability are related.

We have developed a haptic dynamic clamp dedicated to the regulation of arousal. It takes the form of a vibrating stress ball to be squeezed, called Viball, controlled by Righetti's nonlinear adaptive Hopf oscillator. Participants squeezed an adaptive Viball which adapts its frequency of vibration to the current frequency of human squeezing. The adaptive Viball was compared to three non-adaptive Viballs, parametrized to vibrate at a lower, equal, or higher frequency than the participants' preferred frequency. While squeezing the ball, participants looked at stressful or calming pictures and their electrodermal activity was recorded. Using the preference paradigm, we show that participants preferred to interact with the adaptive Viball rather than with the most slowly vibrating ball that most strongly reduced arousal. The stability of the human-ball coordination was the highest with the adaptive Viball. There was also a positive correlation between the stability of coordination and arousal. The data are discussed in light of the energy-based interpretation of coordination dynamics.

Natural Intelligence as the Brain of Intelligent Systems.

This article discusses the concept and applications of cognitive dynamic systems (CDS), which are a type of intelligent system inspired by the brain. There are two branches of CDS, one for linear and Gaussian environments (LGEs), such as cognitive radio and cognitive radar, and another one for non-Gaussian and nonlinear environments (NGNLEs), such as cyber processing in smart systems. Both branches use the same principle, called the perception action cycle (PAC), to make decisions. The focus of this review is on the applications of CDS, including cognitive radios, cognitive radar, cognitive control, cyber security, self-driving cars, and smart grids for LGEs. For NGNLEs, the article reviews the use of CDS in smart e-healthcare applications and software-defined optical communication systems (SDOCS), such as smart fiber optic links. The results of implementing CDS in these systems are very promising, with improved accuracy, performance, and lower computational costs. For example, CDS implementation in cognitive radars achieved a range estimation error that is as good as 0.47 (m) and a velocity estimation error of 3.30 (m/s), outperforming traditional active radars. Similarly, CDS implementation in smart fiber optic links improved the quality factor by 7 dB and the maximum achievable data rate by 43% compared to those of other mitigation techniques.

Road Users Fail to Appreciate the Special Optical Properties of Retroreflective Materials.

OBJECTIVE: To determine whether typical road users appreciate the special optical properties of retroreflective materials. BACKGROUND: Retroreflective surfaces reflect light back towards the source of the illumination. All drivers benefit from retroreflective materials, as they are required on road signs, on large trailers, in lane delineation, and other traffic control devices. Retroreflective markings can also greatly enhance the conspicuity of pedestrians at night, but pedestrians typically underuse retroreflective markings. One possible reason is that pedestrians may not appreciate the special optical properties of retroreflective materials. METHOD: Two experiments tested whether observers could correctly predict that retroreflective materials appear remarkably bright when illuminated by a source that is aligned with the observers' eyes. Observers used a magnitude estimation procedure to predict how bright retroreflective and non-retroreflective stimuli would appear during a demonstration designed to highlight retroreflectivity. They then judged the brightness again during the demonstration. RESULTS: In general, observers underestimated how bright retroreflective stimuli would be and overestimated how bright diffuse reflective and fluorescent stimuli would be. The underestimates for retroreflective stimuli were particularly striking when the observers had not closely examined the stimuli in advance. CONCLUSION: The fact that road users do not appreciate retroreflectivity may help explain why pedestrians underuse retroreflective markings at night. APPLICATION: Educational interventions could prove useful in this domain.

Does the Size-Arrival Effect Occur With an Active Collision-Avoidance Task in an Immersive 3D Virtual Reality Environment?

OBJECTIVE: Determine whether the size-arrival effect (SAE) occurs with immersive, 3D visual experiences and active collision-avoidance responses. BACKGROUND: When a small near object and a large far object approach the observer at the same speeds, the large object appears to arrive before the small object, known as the size-arrival effect (SAE), which may contribute to crashes between motorcycles and cars. Prior studies of the SAE were limited because they used two dimensional displays and asked participants to make passive judgments. METHOD: Participants viewed approaching objects using a virtual reality (VR) headset. In an active task, participants ducked before the object hit them. In a passive prediction-motion (PM) judgment, the approaching object disappeared, and participants pressed a button when they thought the object would hit them. In a passive relative TTC judgment, participants reported which of two approaching objects would reach them first. RESULTS: The SAE occurred with the PM and relative TTC tasks but not with the ducking task. The SAE can occur in immersive 3D environments but is limited by the nature of the task and display. APPLICATION: Certain traffic situations may be more prone to the SAE and have higher risk for collisions. For example, in left-turn scenarios (e.g., see Levulis, 2018), drivers make passive judgments when oncoming vehicles are far and optical expansion is slow, and binocular disparity putatively is ineffective. Collision-avoidance warning systems may be needed more in such scenarios than when vehicles are near and drivers' judgments of TTC may be more accurate (DeLucia, 2008).

Factors That Affect Drivers' Perception of Closing and an Immediate Hazard.

OBJECTIVE: To measure the looming threshold for when drivers perceive closing and an immediate hazard and determine what factors affect these thresholds. BACKGROUND: Rear-end collisions are a common type of crash. One key issue is determining when drivers first perceive they need to react. The looming threshold for closing and an immediate hazard are critical perceptual thresholds that reflect when drivers perceive they need to react. METHOD: Two driving simulator experiments examined whether engaging in a cell phone conversation and whether the complexity of the roadway environment affect these thresholds for the perception of closing and immediate hazard. Half of the participants engaged in a cognitive task, the last letter task, to emulate a cell phone conversation, and all participants experienced both simple and complex roadway environments. RESULTS: Drivers perceived an immediate hazard later when engaged in a cell phone conversation than when not engaged in a conversation but only when the driving task was relatively less demanding (e.g., simple roadway, slow closing velocity). Compared to simple scenes, drivers perceived closing and an immediate hazard later for complex scenes but only when closing velocity was 30 mph (48.28 km/h) or greater. CONCLUSION: Cell phone conversation can affect when drivers perceive an immediate hazard when the roadway is less demanding. Roadway complexity can affect when drivers perceive closing and an immediate hazard when closing velocity is high. APPLICATION: Results can aid accident analysis cases and the design of driving automation systems by suggesting when a typical driver would respond.

Temporal Sensitivity and Latency During Teleoperation: Using Track Clearance to Understand Errors in Future Projection.

OBJECTIVE: This study investigates the role of individual differences in time perception on task performance during teleoperation with latency. BACKGROUND: Long distance teleoperation induces latency, causing performance issues for the operator. Previous research demonstrated that individual differences in time perception predicted performance on a similar task, having participants navigate a radio controlled (RC) car around a track. This work extends the relationship into routes of varying course width to test whether differences in time perception predict movement over-/underestimation. METHOD: Participants completed a time estimation task and a route navigation task while experiencing latency. In the time estimation task, participants estimated the duration of multiple visual stimuli (2 s or less). In the route navigation task, participants moved a virtual cube across a route. Each trial varied in the amount of latency and the amount of horizontal clearance in the track (4-10 m for a 1.2-m-long/wide cube). RESULTS: The results showed fairly consistent latency by time estimation and latency by clearance interaction effects on a wide set of trial-level variables, such as completion time, and action-level performance variables, such as time spent moving per move event. However, the results were not consistently in the predicted direction. CONCLUSION: Results suggest that clearance and timing affect performance across latency, at both the overall level (i.e., trial completion time) and at the action level (time spent moving). An open question remains as to how these contextual factors affect movement strategy selection.

A Visual-Vestibular Model to Predict Motion Sickness for Linear and Angular Motion.

OBJECTIVE: This study proposed a model to predict passenger motion sickness under the presence of a visual-vestibular conflict and assessed its performance with respect to previously recorded experimental data. BACKGROUND: While several models have been shown useful to predict motion sickness under repetitive motion, improvements are still desired in terms of predicting motion sickness in realistic driving conditions. There remains a need for a model that considers angular and linear visual-vestibular motion inputs in three dimensions to improve prediction of passenger motion sickness. METHOD: The model combined the subjective vertical conflict theory and human motion perception models. The proposed model integrates visual and vestibular sensed 6 DoF motion signals in a novel architecture. RESULTS: Model prediction results were compared to motion sickness data obtained from studies conducted in motion simulators as well as on-road vehicle testing, yielding trends that are congruent with observed results in both cases. CONCLUSION: The model demonstrated the ability to predict trends in motion sickness response for conditions in which a passenger performs a task on a handheld device versus facing forward looking ahead under realistic driving conditions. However, further analysis across a larger population is necessary to better assess the model's performance. APPLICATION: The proposed model can be used as a tool to predict motion sickness under different levels of visual-vestibular conflict. This can be leveraged to design interventions capable of mitigating passenger motion sickness. Further, this model can provide insights that aid in the development of passenger experiences inside autonomous vehicles.

The Early Motor Questionnaire revisited: Starting points, standardized scores, and stability.

Motor skills are an important aspect of development during infancy and have been found to predict development in other domains. Therefore, fast and reliable assessments of infant motor skills are needed. The current study revisited a time and cost-effective parent-report measure of infants' motor skills-the Early Motor Questionnaire (EMQ)-and aimed to improve the utility of the EMQ as a tool to examine variability, stability, and individual differences in early motor development. A sample of 446 parents of infants provided a total of 775 EMQ responses for analyses. Using this large sample, regression was used to create age-independent scores for global, gross motor, fine motor, and perception-action scores on the EMQ. Age-adjusted scores were then converted to t-scores to facilitate score interpretation for past and future studies using the EMQ. Finally, starting flags for different age groups were created to decrease the time it takes parents to complete the EMQ. Together, these changes to the EMQ will improve the utility and interpretability of the measure. The EMQ is free to use and available in the supplemental materials or via www.onlinebabylab.com/emq.

Is source elevation an auditory distance cue? A preliminary study.

The aim of this work was to evaluate whether the angular elevation of a sound source could generate auditory cues which improve the auditory distance perception in a similar way to that previously reported by visual modality. For this purpose, we compared ADP curves obtained with sources located both at the listeners' ears and at ground level. Our hypothesis was that the participants can interpret the relation between elevation and distance of ground-level sources (which are linked geometrically) so we expected them to perceive their distances more accurately than those at ear level. However, the responses obtained with sources located at ground level were almost identical to those obtained at the height of the listeners' ears, showing that, under the conditions of our experiment, auditory elevation cues do not influence auditory distance perception.

Auditory perception dominates in motor rhythm reproduction.

It is commonly agreed that vision is more sensitive to spatial information, while audition is more sensitive to temporal information. When both visual and auditory information are available simultaneously, the modality appropriateness hypothesis predicts that, depending on the task, the most appropriate (i.e., reliable) modality dominates perception. While previous research mainly focused on discrepant information from different sensory inputs to scrutinize the modality appropriateness hypothesis, the current study aimed at investigating the modality appropriateness hypothesis when multimodal information was provided in a nondiscrepant and simultaneous manner. To this end, participants performed a temporal rhythm reproduction task for which the auditory modality is known to be the most appropriate. The experiment comprised an auditory (i.e., beeps), a visual (i.e., flashing dots), and an audiovisual condition (i.e., beeps and dots simultaneously). Moreover, constant as well as variable interstimulus intervals were implemented. Results revealed higher accuracy and lower variability in the auditory condition for both interstimulus interval types when compared to the visual condition. More importantly, there were no differences between the auditory and the audiovisual condition across both interstimulus interval types. This indicates that the auditory modality dominated multimodal perception in the task, whereas the visual modality was disregarded and hence did not add to reproduction performance.

Gait Adaptations to Physical Fatigue During the Negotiation of Variable and Unexpected Obstacles.

OBJECTIVE: The purpose of this study was to investigate how physical fatigue impacts one's ability to negotiate unexpected and randomly located obstacles during locomotion. BACKGROUND: Physically demanding occupations place workers at risk of trips and falls-a major health and financial burden. How worker physical fatigue and fitness impacts their ability to navigate through unpredictable environments is not thoroughly explored in current literature. In this exploratory study, we further examine these relationships. METHODS: Twenty-one young, physically fit participants completed a series of obstacle negotiation trials in the dark, where an obstacle would suddenly be illuminated as they reached it. Participants then engaged in a fatigue protocol, before repeating a series of the same negotiation trials. RESULTS: When fatigued, participants exhibited a significant decrease in leading toe and trailing toe clearance, as well as a significant increase in leading heel clearance. Moreover, participants stepped closer to the obstacle with their both feet on the step prior to negotiation. Participants also walked at a faster velocity. Regression analyses revealed that participants' VO2max and height were significant predictors of foot placement metrics. CONCLUSION: Results indicate that physical fatigue negatively impacts crossing mechanics of young, healthy individuals, and that a higher level of VO2 capacity may reduce the occurrences of altered crossing behavior that coincide with physical fatigue. APPLICATION: These results highlight the effect of fatigue on worker safety during performance of job-related duties and are of interest to professionals seeking to reduce the incidence of slips, trips, and falls in the workplace.

An Attentive Blank Stare Under Simulator-induced Spatial Disorientation Events.

OBJECTIVE: This study investigated the effect of the spatial disorientation (SD) events on an attentive blank stare in the cockpit scene and demonstrated how much the flight task and visual delayed discrimination task were competing for the pilots' attention. BACKGROUND: SD in flight is the leading cause of human error-related aircraft accidents in the military, general and commercial aviation, and has been an unsolved problem since the inception of flight. In-flight safety research, visually scanning cockpit instruments, and detecting changes are critical countermeasures against SD. METHOD: Thirty male military pilots were performing a dual task involving piloting a flight simulator and visual change detection, while eye movements were obtained using an eye tracker. RESULTS: Pilots made more flight errors and spent less time gazing at the area of change in SD-conflict than in non-conflict flights. The vestibular origin SD-conflict led not only to deteriorated piloting and visual scanning but also to problems coordinating overt and covert attention, resulting in lower noticeability of visual changes despite gazing at them. CONCLUSION: Our study shows that looking at a given area in space is not a sufficient condition for effective covert attention allocation and the correct response to a visual stimulus. It seems to be important to make pilots aware of this during SD training. APPLICATION: To reduce change blindness, some strategies, such as reducing the number of secondary tasks is extremely valuable. Particular efforts should also be focused on improving the design of the aircraft cockpit by increasing the conspicuousness of critical information.

Negative Consequences of Pressure on Marksmanship May be Offset by Early Training Exposure to Contextually Relevant Threat Training: A Systematic Review and Meta-Analysis.

OBJECTIVE: The purpose of this meta-analytic review is to examine the relationship between increased psychological pressure and Use of Force (UOF) behaviours, identifying current training methodologies and effectiveness of transfer of training interventions in high threat-simulated scenarios. BACKGROUND: Data from UOF performance within Law Enforcement indicates a low transfer of marksmanship training into real-world UOF, resulting in unnecessary damage to property, personal injury and increased risk to loss of life. This meta-analysis examines both the impact of increased pressure and current training interventions. METHOD: A meta-analysis was conducted across a wide range of published research to answer the primary research questions. RESULTS: Increased levels of perceived pressure demonstrated an average decrease in marksmanship accuracy of 14.8%, together with a small increase in incorrect Decision Making (DM) and faster reaction Times (RT). Experience demonstrated a mitigating effect for pressure for marksmanship with a 1.1% increase for every one year of service but no effect on DM or RT. Training interventions utilizing a variety of early contextually relevant exposures to increased pressure improved performance over traditional training on average by 10.6%. CONCLUSION: The outcomes illustrate the negative effect of pressure on marksmanship and UOF behaviours, and that early exposure to contextually relevant pressure may increase the transfer of training to real-world performance. APPLICATION: Occupational experience is an important component in reducing the impact of pressure on UOF performance, and transfer of training may be enhanced through training methodologies that combine early exposure to contextually relevant pressure, that may replicate the benefits of experience.

Learning different task spaces: how explored density aligns the Quiet Eye.

In the current study, predictions of a theoretical account to the explanation of the Quiet Eye (QE) were investigated. To this end, by manipulating the learning environment, participants (n = 52) learned an underhand throwing task which required to explore task-solution spaces of low vs. high density over a 4-week training phase (640 training trials). Although throwing performance was improved, surprisingly, in posttest and retention test shorter QE durations were found. It is speculated that on a short-time learning scale this effect might be explained by more efficient information processing. Moreover, a trend was observed which suggests that-in line with the inhibition hypothesis-when exploring high-density task-solution spaces longer QE durations are required. However, the rather small effect sizes necessitate further research, which will allow to manipulate the response-effect mappings more directly as, for example, in virtual environments.