The impact of eye gaze on social interactions of females in virtual reality: The mediating role of the uncanniness of avatars and the moderating role of task type.

The introduction of the Metaverse and the rise of social virtual reality platforms such as VRChat has led to increased communication and collaboration in virtual reality. As interactions in social virtual reality take place through avatars, the behaviour, and in particular the eye gaze of an avatar can have an impact on the user experience. However, it is still unclear which features of the user experience are most influenced. Therefore, this study used data from 44 female participants to investigate how avatar gaze behaviour (static eyes vs. real-time tracked eyes) affects their perceived quality of communication and the amount of one-sided eye contact participants make during a communicative or collaborative task in virtual reality. In addition, the study investigated the mediating role of perceived avatar "uncanniness" (i.e., the finding that humanoid objects that imperfectly resemble real people evoke feelings of discomfort) in this relationship and the moderation effect of two multi-user scenarios (collaboration vs. communication). The results showed that uncanniness directly affected the perceived quality of communication. However, it did not significantly mediate the relationship between avatar eye gaze behaviour and the quality of communication or the amount of one-sided eye contact. Finally, there were no significant differences in user experience between the two scenarios. From this, we can conclude that the uncanniness of an avatar being interacted with in VR is not enough to hinder communication and collaboration in an immersive medium. And even if an avatar is perceived as uncanny, normative communication cues such as eye contact are still present. Notably, due to sample availability, the results of this study are based on a female-only sample. Thus, future research can benefit from exploring the outlined effects in a more gender-balanced sample.

Evidence for a two-step model of social group influence.

Social group influence plays an important role in societally relevant phenomena such as rioting and mass panic. One way through which groups influence individuals is by directing their gaze. Evidence that gaze following increases with group size has typically been explained in terms of strategic processes. Here, we tested the role of reflexive processes. In an ecologically valid virtual reality task, we found that participants were more likely to follow the group's gaze when more people looked, even though they knew the group provided no relevant information. Interestingly, participants also sometimes changed their mind after starting to follow the gaze of the group, indicating that automatic imitation can be overruled by strategic processes. This suggests that social group influence is best explained by a two-step model in which bottom-up imitative processes first elicit a reflexive tendency to imitate, before top-down strategic processes determine whether to execute or inhibit this reflex.

Molecular detection of SARS-COV-2 in exhaled breath at the point-of-need.

The SARS-CoV-2 pandemic has highlighted the need for improved technologies to help control the spread of contagious pathogens. While rapid point-of-need testing plays a key role in strategies to rapidly identify and isolate infectious patients, current test approaches have significant shortcomings related to assay limitations and sample type. Direct quantification of viral shedding in exhaled particles may offer a better rapid testing approach, since SARS-CoV-2 is believed to spread mainly by aerosols. It assesses contagiousness directly, the sample is easy and comfortable to obtain, sampling can be standardized, and the limited sample volume lends itself to a fast and sensitive analysis. In view of these benefits, we developed and tested an approach where exhaled particles are efficiently sampled using inertial impaction in a micromachined silicon chip, followed by an RT-qPCR molecular assay to detect SARS-CoV-2 shedding. Our portable, silicon impactor allowed for the efficient capture (>85%) of respiratory particles down to 300 nm without the need for additional equipment. We demonstrate using both conventional off-chip and in-situ PCR directly on the silicon chip that sampling subjects' breath in less than a minute yields sufficient viral RNA to detect infections as early as standard sampling methods. A longitudinal study revealed clear differences in the temporal dynamics of viral load for nasopharyngeal swab, saliva, breath, and antigen tests. Overall, after an infection, the breath-based test remains positive during the first week but is the first to consistently report a negative result, putatively signalling the end of contagiousness and further emphasizing the potential of this tool to help manage the spread of airborne respiratory infections.

Danger, high voltage! Using EEG and EOG measurements for cognitive overload detection in a simulated industrial context.

Industrial settings will be characterized by far-reaching production automation brought about by advancements in robotics and artificial intelligence. As a consequence, human assembly workers will need to adapt quickly to new and more complex assembly procedures, which are most likely to increase cognitive workload, or potentially induce overload. Measurement and optimization protocols need to be developed in order to be able to monitor workers' cognitive load. Previous studies have used electroencephalographic (EEG, measuring brain activity) and electrooculographic (EOG, measuring eye movements) signals, using basic computer-based static tasks and without creating an experience of overload. In this study, EEG and EOG data was collected of 46 participants performing an ecologically valid assembly task while inducing three levels of cognitive load (low, high and overload). The lower individual alpha frequency (IAF) was identified as a promising marker for discriminating between different levels of cognitive load and overload.

Development and validation of a behavioural video coding scheme for detecting mental workload in manual assembly.

Manual assembly in the future Industry 4.0 workplace will put high demands on operators' cognitive processing. The development of mental workload (MWL) measures therefore looms large. Physiological gauges such as electroencephalography (EEG) show promising possibilities, but still lack sufficient reliability when applied in the field. This study presents an alternative measure with a substantial ecological validity. First, we developed a behavioural video coding scheme identifying 11 assembly behaviours potentially revealing MWL being too high. Subsequently, we explored its validity by analysing videos of 24 participants performing a high and a low complexity assembly. Results showed that five of the behaviours identified, such as freezing and the amount of part rotations, significantly differed in occurrence and/or duration between the two conditions. The study hereby proposes a novel and naturalistic method that could help practitioners to map and redesign critical assembly phases, and researchers to enrich validation of MWL-measures through measurement triangulation. Practitioner summary: Current physiological mental workload (MWL) measures still lack sufficient reliability when applied in the field. Therefore, we identified several observable assembly behaviours that could reveal MWL being too high. The results propose a method to map MWL by observing specific assembly behaviours such as freezing and rotating parts. Abbreviations: MWL: mental workload; EEG: electroencephalography; fNIRS: functional near infrared spectroscopy; AOI: area of interest; SMI: SensoMotoric Instruments, ETG: Eye-Tracking Glasses; FPS: frames per second; BORIS: Behavioral Observation Research Interactive Software; IRR: inter-rater reliability; SWAT: Subjective Workload Assessment Technique; NASA-TLX: National Aeronautics and Space Administration Task Load Index; EL: emotional load; DSSQ: Dundee Stress State Questionnaire; PHL: physical load; SBO: Strategisch Basis Onderzoek.

Differential effects of sustained and transient effort triggered by reward - A combined EEG and pupillometry study.

In instrumental task contexts, incentive manipulations such as posting reward on successful performance usually trigger increased effort, which is signified by effort markers like increased pupil size. Yet, it is not fully clear under which circumstances incentives really promote performance, and which role effort plays therein. In the present study, we compared two schemes of associating reward with a Flanker task, while simultaneously acquiring electroencephalography (EEG) and pupillometry data in order to explore the contribution of effort-related processes. In Experiment 1, reward was administered in a block-based fashion, with series of targets in pure reward and no-reward blocks. The results imply increased sustained effort in the reward blocks, as reflected in particular in sustained increased pupil size. Yet, this was not accompanied by a behavioral benefit, suggesting a failure of translating increased effort into a behavioral pay-off. In Experiment 2, we introduced trial-based cues in order to also promote transient preparatory effort application, which indeed led to a behavioral benefit. Again, we observed a sustained pupil-size increase, but also transient ones. Consistent with this, the EEG data of Experiment 2 indicated increased transient preparatory effort preceding target onset, as well as reward modulations of target processing that arose earlier than in Experiment 1. Jointly, our results indicate that incentive-triggered effort can operate on different time-scales, and that, at least for the current task, its transient (and largely preparatory) form is critical for achieving a behavioral benefit, which may relate to the temporal dynamics of the catecholaminergic systems.

Modulation of locus coeruleus activity by novel oddball stimuli.

It has long been known from animal literature that the locus coeruleus (LC), the source region of noradrenergic neurons in the brain, is sensitive to unexpected, novel, and other salient events. In humans, however, direct assessment of LC activity has proven to be challenging due to its small size and difficult localization, which is why noradrenergic activity has often been assessed using more indirect measures such as electroencephalography (EEG) and pupil recordings. Here, we combined high-resolution functional magnetic resonance imaging (fMRI) with a special anatomical sequence to assess neural activity in the LC in response to different types of salient stimuli in an oddball paradigm (novel neutral oddballs, novel emotional oddballs, and familiar target oddballs). We found a significant linear increase of LC activity from standard trials, over familiar target oddballs, to novel neutral and novel emotional oddballs. Importantly, when breaking down this linear trend, only novel oddball stimuli led to robust activity increases as compared to standard trials, with no statistical difference between neutral and emotional ones. This pattern suggests that activity modulations in the LC in the present study were mainly driven by stimulus novelty, rather than by emotional saliency, task relevance, or contextual novelty alone. Moreover, the absence of significant activity modulations in response to target oddballs (which were reported in a recent study) suggests that the LC represents relative rather than absolute saliency of a stimulus in its respective context.

The role of temporal predictability for early attentional adjustments after conflict.

A frequently-studied phenomenon in cognitive-control research is conflict adaptation, or the finding that congruency effects are smaller after incongruent trials. Prominent cognitive control accounts suggest that this adaptation effect can be explained by transient conflict-induced modulations of selective attention, reducing congruency effects on the next trial. In the present study, we investigated these possible attentional modulations in four experiments using the Stroop and Flanker tasks, dissociating possible enhancements of task-relevant information from suppression of task-irrelevant information by varying when this information was presented. In two experiments, the irrelevant stimulus information was randomly presented shortly before, at the same time, or briefly after the presentation of the relevant dimension. In the other two, irrelevant information was always presented first, making this aspect fully predictable. Despite the central role that attentional adjustments play in theoretical accounts of conflict adaption, we only found evidence for such processes in one of the four experiments. Specifically, we found a modulation of the attention-related posterior N1 event-related potential component that was consistent with paying less attention to the irrelevant information after incongruent trials. This was accompanied by increased inter-trial mid-frontal theta power and a theta-power conflict adaptation effect. We interpret these results as evidence for an adaptive mechanism based on relative attentional inhibition. Importantly, this mechanism only clearly seems to be implemented in a very specific context of high temporal predictability, and only in the Flanker task.

The effect of vagus nerve stimulation on response inhibition.

In the current study, we explored whether vagus nerve stimulation (VNS) in patients with epilepsy, which is believed to increase norepinephrine (NE) levels via activation of the locus coeruleus, would positively affect response inhibition. Moreover, we tried to identify the dynamics of the underlying neural processes by investigating event-related potentials (ERPs) and pupil size. Patients performed a stop-signal task once when stimulation was switched on and once when it was switched off. We found a correlational pattern suggesting that patients who clinically benefit more from VNS treatment also show a larger behavioral advantage, in terms of faster response inhibition, when the vagus nerve is being stimulated. Event-related potential (ERP) results suggested more pronounced reactive inhibition when stimulation was switched on, independent of the individual amount of seizure reduction. Transient go-locked pupil size was increased from go trials to successful stop trials to unsuccessful stop trials but without displaying a clear VNS effect, which however, might relate to limited sensitivity. We conclude that VNS likely has a positive effect on response inhibition, at least in patients with epilepsy that benefit clinically from the treatment, presumably relating to enhancements of response-inhibition mechanisms and, therefore, identify enhanced response inhibition as a possible cognitive benefit of VNS.

Preparing for (valenced) action: The role of differential effort in the orthogonalized go/no-go task.

Associating reward to task performance has been shown to benefit scores of cognitive functions. Importantly, this typically entails associating reward to the execution of a response, hence intertwining action-related processes with motivational ones. However, recently, preparatory action requirements (go/no-go) and outcome valence (reward/punishment) were elegantly separated using a cued orthogonalized go/no-go task. Functional magnetic resonance imaging results from this task showed that typical areas of the "reward network," like the dopaminergic midbrain and the striatum, predominantly encode action rather than valence, displaying enhanced activity when preparing for action (go) compared to inaction (no-go). In the current study, we used ERPs to probe for differences in preparatory state related to cognitive effort in this task, which has similarly been linked to reward-network activity. Importantly, the contingent negative variation, which is linked to effortful cognitive preparation processes during cue-target intervals, was clearly observed in go trials but not in no-go trials. Moreover, target-locked ERP results (N1 and P3) suggested that attention to the target was enhanced when an action had to be performed (go trials), and typical inhibition-related ERP components were not observed in no-go trials, suggesting a lack of active response inhibition. Finally, feedback-related P3 results could suggest that correct feedback was valued more in motivated go trials, again implying that more effort was required to correctly perform the task. Together, these results indicate that the anticipation of action compared to inaction simultaneously entails differences in mental effort, highlighting the need for further dissociation of these concepts.

Pupil size directly modulates the feedforward response in human primary visual cortex independently of attention.

Controversy revolves around the question of whether psychological factors like attention and emotion can influence the initial feedforward response in primary visual cortex (V1). Although traditionally, the electrophysiological correlate of this response in humans (the C1 component) has been found to be unaltered by psychological influences, a number of recent studies have described attentional and emotional modulations. Yet, research into psychological effects on the feedforward V1 response has neglected possible direct contributions of concomitant pupil-size modulations, which are known to also occur under various conditions of attentional load and emotional state. Here we tested the hypothesis that such pupil-size differences themselves directly affect the feedforward V1 response. We report data from two complementary experiments, in which we used procedures that modulate pupil size without differences in attentional load or emotion while simultaneously recording pupil-size and EEG data. Our results confirm that pupil size indeed directly influences the feedforward V1 response, showing an inverse relationship between pupil size and early V1 activity. While it is unclear in how far this effect represents a functionally-relevant adaptation, it identifies pupil-size differences as an important modulating factor of the feedforward response of V1 and could hence represent a confounding variable in research investigating the neural influence of psychological factors on early visual processing.

Electrophysiological evidence for the involvement of proactive and reactive control in a rewarded stop-signal task.

Reward availability is known to facilitate various cognitive operations, which is usually studied in cue-based paradigms that allow for enhanced preparation in reward-related trials. However, recent research using tasks that signal reward availability via task-relevant stimuli suggests that reward can also rapidly promote performance independent of global strategic preparation. Notably, this effect was also observed in a reward-related stop-signal task, in which behavioral measures of inhibition speed were found to be shorter in trials signaling reward. Corresponding fMRI results implied that this effect relies on boosted reactive control as indicated by increased activity in the 'inhibition-related network' in the reward-related condition. Here, we used EEG to better characterize transient modulations of attentional processes likely preceding this ultimate implementation of response inhibition. Importantly, such modulations would probably reflect enhanced proactive control in the form of more top-down attention to reward-related features. Counter to the notion that behavioral benefits would rely purely on reactive control, we found increased stop-evoked attentional processing (larger N1 component) on reward-related trials. This effect was accompanied by enhanced frontal P3 amplitudes reflecting successful stopping, and earlier and larger ERP differences between successful and failed stop trials in the reward-related condition. Finally, more global proactive control processes in the form of a reward context modulation of reward-unrelated trials did not have an effect on stopping performance but did influence attentional processing of go stimuli. Together, these results suggest that proactive and reactive processes can interact to bring about stimulus-specific reward benefits when the task precludes differential global preparation.

Open your eyes for prediction errors.

Previous studies have demonstrated that autonomic arousal is increased following correct task performance on a difficult, relative to an easy, task. Here, we hypothesized that this arousal response reflects the (relative) surprise of correct performance following a difficult versus an easy task. Following this line of reasoning, we would expect to find a reversed pattern following erroneous responses, because errors are less expected during an easy than during a difficult task. To test this, participants performed a flanker task while pupil size was measured online. As predicted, the results demonstrated that pupil size was larger following difficult (incongruent) correct trials than following easy (congruent) correct trials, but smaller following difficult than following easy incorrect trials. Moreover, participants with larger congruency effects, and hence a larger difference in outcome expectancies between the two trial types, showed larger differences in pupil size after both correct and incorrect responses, further corroborating the idea that pupil size increased as a measure of performance prediction errors.

The effect of alcohol and placebo on post-error adjustments.

Several studies have shown detrimental effects of alcohol on post-error adjustments. In contrast to previous studies, which focused on only one aspect of post-error adaptive behavior, we compared the effect of alcohol and placebo on post-error slowing (PES), post-error reduction of interference (PERI) and post-error improvement of accuracy (PIA). Moreover, we used a between-subjects design (N = 45) comparing a control condition to both an alcohol and an alcohol-placebo condition as to disentangle physiological and expectancy effects of alcohol. In a standard Stroop congruency task, we found that intoxicated participants as well as participants with the incorrect belief of being intoxicated showed significant decreased PES compared to a control group. Furthermore, we found evidence for a condition-independent post-error increase of interference and post-error decrease of accuracy. The underlying mechanisms of the post-error adaptation effects are discussed in terms of the orienting account (Notebaert et al., 2009).