GlassesValidator: A data quality tool for eye tracking glasses.

According to the proposal for a minimum reporting guideline for an eye tracking study by Holmqvist et al. (2022), the accuracy (in degrees) of eye tracking data should be reported. Currently, there is no easy way to determine accuracy for wearable eye tracking recordings. To enable determining the accuracy quickly and easily, we have produced a simple validation procedure using a printable poster and accompanying Python software. We tested the poster and procedure with 61 participants using one wearable eye tracker. In addition, the software was tested with six different wearable eye trackers. We found that the validation procedure can be administered within a minute per participant and provides measures of accuracy and precision. Calculating the eye-tracking data quality measures can be done offline on a simple computer and requires no advanced computer skills.

How robust are wearable eye trackers to slow and fast head and body movements?

How well can modern wearable eye trackers cope with head and body movement? To investigate this question, we asked four participants to stand still, walk, skip, and jump while fixating a static physical target in space. We did this for six different eye trackers. All the eye trackers were capable of recording gaze during the most dynamic episodes (skipping and jumping). The accuracy became worse as movement got wilder. During skipping and jumping, the biggest error was 5.8∘. However, most errors were smaller than 3∘. We discuss the implications of decreased accuracy in the context of different research scenarios.

Eye tracking: empirical foundations for a minimal reporting guideline.

In this paper, we present a review of how the various aspects of any study using an eye tracker (such as the instrument, methodology, environment, participant, etc.) affect the quality of the recorded eye-tracking data and the obtained eye-movement and gaze measures. We take this review to represent the empirical foundation for reporting guidelines of any study involving an eye tracker. We compare this empirical foundation to five existing reporting guidelines and to a database of 207 published eye-tracking studies. We find that reporting guidelines vary substantially and do not match with actual reporting practices. We end by deriving a minimal, flexible reporting guideline based on empirical research (Section "An empirically based minimal reporting guideline").

Snacking for a reason: detangling effects of socio-economic position and stress on snacking behaviour.

BACKGROUND: As snacking can be considered a cornerstone of an unhealthy diet, investigating psychological drivers of snacking behaviour is urgent, and therefore the purpose of this study. Socio-economic position (SEP) and stress are known to affect many behaviours and outcomes, and were therefore focal points in the study. METHODS: In a cross-sectional survey study, we examined whether Socio-economic position (SEP) would amplify associations between heightened stress levels and self-reported negative-affect related reasons for snacking. Next, we investigated whether Socio-economic position (SEP) predicted frequency of snacking behaviour, and how stress and other reasons for snacking could explain this association. Outcome measures were reasons people indicated for snacking, and frequency of snacking behaviour. RESULTS: Analyses revealed that people seem to find more reasons to snack when they are stressed, and that this association was more pronounced for people with a high compared to low socio-economic position. Furthermore, a higher socio-economic position was associated with a higher frequency of snacking, and both snacking to reward oneself and snacking because of the opportunity to do so remained significant mediators. CONCLUSION: Whereas low socio-economic position was associated with higher stress levels, this did not translate into increased snacking. Contrarily, those with higher socio-economic position could be more prone to using 'reasons to snack', which may result in justification of unhealthy snacking behaviour.

Looking behavior and potential human interactions during locomotion.

As humans move through parts of their environment, they meet others that may or may not try to interact with them. Where do people look when they meet others? We had participants wearing an eye tracker walk through a university building. On the way, they encountered nine "walkers." Walkers were instructed to e.g. ignore the participant, greet him or her, or attempt to hand out a flyer. The participant's gaze was mostly directed to the currently relevant body parts of the walker. Thus, the participants gaze depended on the walker's action. Individual differences in participant's looking behavior were consistent across walkers. Participants who did not respond to the walker seemed to look less at that walker, although this difference was not statistically significant. We suggest that models of gaze allocation should take social motivation into account.

GlassesViewer: Open-source software for viewing and analyzing data from the Tobii Pro Glasses 2 eye tracker.

We present GlassesViewer, open-source software for viewing and analyzing eye-tracking data of the Tobii Pro Glasses 2 head-mounted eye tracker as well as the scene and eye videos and other data streams (pupil size, gyroscope, accelerometer, and TTL input) that this headset can record. The software provides the following functionality written in MATLAB: (1) a graphical interface for navigating the study- and recording structure produced by the Tobii Glasses 2; (2) functionality to unpack, parse, and synchronize the various data and video streams comprising a Glasses 2 recording; and (3) a graphical interface for viewing the Glasses 2's gaze direction, pupil size, gyroscope and accelerometer time-series data, along with the recorded scene and eye camera videos. In this latter interface, segments of data can furthermore be labeled through user-provided event classification algorithms or by means of manual annotation. Lastly, the toolbox provides integration with the GazeCode tool by Benjamins et al. (2018), enabling a completely open-source workflow for analyzing Tobii Pro Glasses 2 recordings.

Slow dissolving of emotional distress contributes to hyperarousal.

The mechanisms underlying hyperarousal, the key symptom of insomnia, have remained elusive, hampering cause-targeted treatment. Recently, restless rapid-eye-movement (REM) sleep emerged as a robust signature of sleep in insomnia. Given the role of REM sleep in emotion regulation, we hypothesized that restless REM sleep could interfere with the overnight resolution of emotional distress, thus contributing to accumulation of arousal. Participants (n = 1,199) completed questionnaires on insomnia severity, hyperarousal, self-conscious emotional distress, and thought-like nocturnal mentation that was validated to be a specific proxy for restless REM sleep (selective fragmentation: R = 0.57, P < 0.001; eye movement density: R = 0.46, P < 0.01) in 32 polysomnographically assessed participants. The experience of distress lasting overnight increased with insomnia severity (ß = 0.29, P < 10(-23)), whereas short-lasting distress did not (ß = -0.02, P = 0.41). Insomnia severity was associated with hyperarousal (ß = 0.47, P < 10(-63)) and with the thought-like nocturnal mentation that is specifically associated with restless REM sleep (ß = 0.31, P < 10(-26)). Structural equation modeling showed that 62.4% of the association between these key characteristics of insomnia was mediated specifically by reduced overnight resolution of emotional distress. The model outperformed all alternative mediation pathways. The findings suggest that restless REM sleep reflects a process that interferes with the overnight resolution of distress. Its accumulation may promote the development of chronic hyperarousal, giving clinical relevance to the role of REM sleep in emotion regulation in insomnia, depression, and posttraumatic stress disorder.

Memory effects of sleep, emotional valence, arousal and novelty in children.

Effectiveness of memory consolidation is determined by multiple factors, including sleep after learning, emotional valence, arousal and novelty. Few studies investigated how the effect of sleep compares with (and interacts with) these other factors, of which virtually none are in children. The present study did so by repeated assessment of declarative memory in 386 children (45% boys) aged 9-11 years through an online word-pair task. Children were randomly assigned to either a morning or evening learning session of 30 unrelated word-pairs with positive, neutral or negative valenced cues and neutral targets. After immediately assessing baseline recognition, delayed recognition was recorded either 12 or 24 h later, resulting in four different assessment schedules. One week later, the procedure was repeated with exactly the same word-pairs to evaluate whether effects differed for relearning versus original novel learning. Mixed-effect logistic regression models were used to evaluate how the probability of correct recognition was affected by sleep, valence, arousal, novelty and their interactions. Both immediate and delayed recognition were worse for pairs with negatively valenced or less arousing cue words. Relearning improved immediate and delayed word-pair recognition. In contrast to these effects, sleep did not affect recognition, nor did sleep moderate the effects of arousal, valence and novelty. The findings suggest a robust inclination of children to specifically forget the pairing of words to negatively valenced cue words. In agreement with a recent meta-analysis, children seem to depend less on sleep for the consolidation of information than has been reported for adults, irrespective of the emotional valence, arousal and novelty of word-pairs.

Temperament moderates the association between sleep duration and cognitive performance in children.

The importance of sufficient sleep for cognitive performance has been increasingly recognized. Individual differences in susceptibility to effects of sleep restriction have hardly been investigated in children. We investigated whether individual differences in temperament moderate the association of sleep duration with sustained attention, inhibition, and working memory in 123 children (42% boys) aged 9 to 11 years. Sleep duration was assessed using parental diaries, and temperament traits of extraversion and negative affectivity were assessed by child self-report (Early Adolescent Temperament Questionnaire-Revised). Computerized assessment of sustained attention (short-form Psychomotor Vigilance Task, PVT), inhibition (PVT Go/No-Go adaptation), and working memory (visual Digit Span) were performed at school. Our findings demonstrate that long-sleeping introverted and negatively affective children show worse sustained attention and working memory than short-sleeping children with these temperaments.

The role of sleep timing in children's observational learning.

Acquisition of information can be facilitated through different learning strategies, classically associated with either declarative or procedural memory modalities. The consolidation of the acquired information has been positively associated with sleep. In addition, subsequent performance was better when acquisition was quickly followed by sleep, rather than daytime wakefulness. Prior studies with adults have indicated the viability of the alternative learning strategy of observational learning for motor skill acquisition, as well as the importance of sleep and sleep timing. However, relatively little research has been dedicated to studying the importance of sleep for the consolidation of procedural memory in children. Therefore, this study investigated whether children could encode procedural information through observational learning, and whether sleep timing could affect subsequent consolidation and performance. School-aged children aged 9-12years (N=86, 43% male, Mage=10.64years, SD=.85) were trained on a procedural fingertapping task through observation, either in the morning or evening; creating immediate wake and immediate sleep groups, respectively. Performance was evaluated the subsequent evening or morning on either a congruent or incongruent task version. Observation and task execution was conducted using an online interface, allowing for remote participation. Performance of the immediate wake group was lower for a congruent version, expressed by a higher error rate, opposed to an incongruent version; an effect not observed in the immediate sleep group. This finding showed that observational learning did not improve performance in children. Yet, immediate sleep prevented performance reduction on the previously observed task. These results support a benefit of sleep in observational learning in children, but in a way different from that seen in adults, where sleep enhanced performance after learning by observation.

The role of attention and health goals in nudging healthy food choice.

Introduction: Nudging is a promising intervention technique that supports people in pursuing their healthy eating goals. Recent research suggests that, despite previous assumptions, disclosure of the presence of a nudge does not compromise nudge effectiveness. However, it is unknown whether attention to a nudge affects nudge effects. We assessed the role of attention systematically, by examining explicit and implicit attention to nudges, while also exploring healthy eating goals as a potential moderator. Methods: Participants were assigned to a nudge (i.e., a shopping basket inlay with pictures of healthy items) or control condition (i.e., a shopping basket inlay with neutral pictures) and chose a snack in an experimental supermarket field study. Explicit and implicit attention (with a mobile eye-tracker) to nudges, healthiness of snack choice, and healthy eating goals were assessed. Results: Results showed that attention to the nudge did not hamper the nudge's effect. Furthermore, individuals with strong healthy eating goals made healthier food choices in the nudge condition. Individuals with weak to non-existent healthy eating goals were not influenced by the nudge. Discussion: Findings are in line with the viewpoint that nudging does not by definition work 'in the dark', and suggests that nudges support people in adhering to their healthy eating goal.

Eye contact avoidance in crowds: A large wearable eye-tracking study.

Eye contact is essential for human interactions. We investigated whether humans are able to avoid eye contact while navigating crowds. At a science festival, we fitted 62 participants with a wearable eye tracker and instructed them to walk a route. Half of the participants were further instructed to avoid eye contact. We report that humans can flexibly allocate their gaze while navigating crowds and avoid eye contact primarily by orienting their head and eyes towards the floor. We discuss implications for crowd navigation and gaze behavior. In addition, we address a number of issues encountered in such field studies with regard to data quality, control of the environment, and participant adherence to instructions. We stress that methodological innovation and scientific progress are strongly interrelated.

Perception of the Potential for Interaction in Social Scenes.

In urban environments, humans often encounter other people that may engage one in interaction. How do humans perceive such invitations to interact at a glance? We briefly presented participants with pictures of actors carrying out one of 11 behaviors (e.g., waving or looking at a phone) at four camera-actor distances. Participants were asked to describe what they might do in such a situation, how they decided, and what stood out most in the photograph. In addition, participants rated how likely they deemed interaction to take place. Participants formulated clear responses about how they might act. We show convincingly that what participants would do depended on the depicted behavior, but not the camera-actor distance. The likeliness to interact ratings depended both on the depicted behavior and the camera-actor distance. We conclude that humans perceive the "gist" of photographs and that various aspects of the actor, action, and context depicted in photographs are subjectively available at a glance. Our conclusions are discussed in the context of scene perception, social robotics, and intercultural differences.

Episodic and semantic memory processes in the boundary extension effect: An investigation using the remember/know paradigm.

BACKGROUND: Boundary extension (BE) is a phenomenon where participants report from memory that they have experienced more information of a scene than was initially presented. The goal of the current study was to investigate whether BE is fully based on episodic memory or also involves semantic scheme knowledge. METHODS: The study incorporated the remember/know paradigm into a BE task. Scenes were first learned incidentally, with participants later indicating whether they remembered or knew that they had seen the scene before. Next, they had to rate 3 views - zoomed in, zoomed out or unchanged - of the original picture on similarity in closeness in order to measure BE. RESULTS: The results showed a systematic BE pattern, but no difference in the amount of BE for episodic ('remember') and semantic ('know') memory. Additionally, the remember/know paradigm used in this study showed good sensitivity for both the remember and know responses. DISCUSSION: The results suggest that BE might not critically depend on the contextual information provided by episodic memory, but rather depends on schematic knowledge shared by episodic and semantic memory. Schematic knowledge might be involved in BE by providing an expectation of what likely lies beyond the boundaries of the scene based on semantic guidance. GEL CLASSIFICATION: 2343 learning & memory.

When in Doubt, Follow the Crowd? Responsiveness to Social Proof Nudges in the Absence of Clear Preferences.

Nudges have gained popularity as a behavioral change tool that aims to facilitate the selection of the sensible choice option by altering the way choice options are presented. Although nudges are designed to facilitate these choices without interfering with people's prior preferences, both the relation between individuals' prior preferences and nudge effectiveness, as well as the notion that nudges 'facilitate' decision-making have received little empirical scrutiny. Two studies examine the hypothesis that a social proof nudge is particularly effective when people have no clear prior preference, either because people are indifferent (in a color-categorization task; Study 1, N = 255) or because people experience a choice conflict (making shopping decisions about meat products; Study 2, N = 97). Both studies employed a social proof nudge to steer participants' choices. The potential facilitating effect of the nudge was tested using a mouse-tracker paradigm that implicitly assessed experienced uncertainty during decision-making. Results showed that the nudge was effective in steering participants' decisions; the facilitation effect (i.e., reduced uncertainty regarding the decision) was only observed for conflicting preferences, but not under indifference. A better understanding of when and how nudges can influence individuals' behavior may help in deciding whether nudges are an appropriate policy tool for changing particular undesirable behavior.

Task-related gaze control in human crowd navigation.

Human crowds provide an interesting case for research on the perception of people. In this study, we investigate how visual information is acquired for (1) navigating human crowds and (2) seeking out social affordances in crowds by studying gaze behavior during human crowd navigation under different task instructions. Observers (n = 11) wore head-mounted eye-tracking glasses and walked two rounds through hallways containing walking crowds (n = 38) and static objects. For round one, observers were instructed to avoid collisions. For round two, observers furthermore had to indicate with a button press whether oncoming people made eye contact. Task performance (walking speed, absence of collisions) was similar across rounds. Fixation durations indicated that heads, bodies, objects, and walls maintained gaze comparably long. Only crowds in the distance maintained gaze relatively longer. We find no compelling evidence that human bodies and heads hold one's gaze more than objects while navigating crowds. When eye contact was assessed, heads were fixated more often and for a total longer duration, which came at the cost of looking at bodies. We conclude that gaze behavior in crowd navigation is task-dependent, and that not every fixation is strictly necessary for navigating crowds. When explicitly tasked with seeking out potential social affordances, gaze is modulated as a result. We discuss our findings in the light of current theories and models of gaze behavior. Furthermore, we show that in a head-mounted eye-tracking study, a large degree of experimental control can be maintained while many degrees of freedom on the side of the observer remain.

An eye-tracking approach to Autonomous sensory meridian response (ASMR): The physiology and nature of tingles in relation to the pupil.

Autonomous sensory meridian response (ASMR) is a sensory phenomenon commonly characterized by pleasant tingling sensations arising from the back of the head and accompanied by feelings of relaxation and calmness. Although research has found ASMR to have a distinct physiological pattern with increased skin conductance levels and reduced heart rate, the specific tingles felt in ASMR have not received much investigation. The aim of the present study was to investigate the physiology and characteristics of ASMR further by examining whether experiencing ASMR is visible from the pupil of the eye. A total of 91 participants were recruited and assigned to three different groups based on their experience of ASMR (ASMR vs. non-ASMR vs. unsure). Participants were instructed to watch a control video and an ASMR video and to report any tingling sensations by pressing down a button on the keyboard. Pupil diameter was measured over the duration of both videos using a tower-mounted eye tracker. Data was analyzed on a general level, averaging pupil diameter over each video, as well as on a more specific level, comparing pupil diameter during reported episodes of tingling sensations to pupil diameter outside of those episodes. On the general level, results revealed no significant differences between the groups. On the specific level, however, the tingling sensations experienced in ASMR were found to cause statistically significant increases in pupil diameter, demonstrating that they have a physiological basis. The results of the study further reinforce the credibility of ASMR and suggest that the tingles felt in ASMR are at the very core of the experience itself.