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.

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 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").

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.

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.

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.

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.

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.

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.

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.

Genome-wide analysis of insomnia in 1,331,010 individuals identifies new risk loci and functional pathways.

Insomnia is the second most prevalent mental disorder, with no sufficient treatment available. Despite substantial heritability, insight into the associated genes and neurobiological pathways remains limited. Here, we use a large genetic association sample (n = 1,331,010) to detect novel loci and gain insight into the pathways, tissue and cell types involved in insomnia complaints. We identify 202 loci implicating 956 genes through positional, expression quantitative trait loci, and chromatin mapping. The meta-analysis explained 2.6% of the variance. We show gene set enrichments for the axonal part of neurons, cortical and subcortical tissues, and specific cell types, including striatal, hypothalamic, and claustrum neurons. We found considerable genetic correlations with psychiatric traits and sleep duration, and modest correlations with other sleep-related traits. Mendelian randomization identified the causal effects of insomnia on depression, diabetes, and cardiovascular disease, and the protective effects of educational attainment and intracranial volume. Our findings highlight key brain areas and cell types implicated in insomnia, and provide new treatment targets.

Insomnia disorder subtypes derived from life history and traits of affect and personality.

BACKGROUND: Insomnia disorder is the second most prevalent mental disorder, and it is a primary risk factor for depression. Inconsistent clinical and biomarker findings in patients with insomnia disorder suggest that heterogeneity exists and that subtypes of this disease remain unrecognised. Previous top-down proposed subtypes in nosologies have had insufficient validity. In this large-scale study, we aimed to reveal robust subtypes of insomnia disorder by use of data-driven analyses on a multidimensional set of biologically based traits. METHODS: In this series of studies, we recruited participants from the Netherlands Sleep Registry, a database of volunteers aged 18 years or older, who we followed up online to survey traits, sleep, life events, and health history with 34 selected questionnaires of which participants completed at least one. We identified insomnia disorder subtypes by use of latent class analyses. We evaluated the value of our identified subtypes of insomnia disorder by use of a second, non-overlapping cohort who were recruited through a newsletter that was emailed to a new sample of Netherlands Sleep Registry participants, and by assessment of within-subject stability over several years of follow-up. We extensively tested the clinical validity of these subtypes for the development of sleep complaints, comorbidities (including depression), and response to benzodiazepines; in two subtypes of insomnia disorder, we also assessed the clinical relevance of these subtypes by use of an electroencephalogram biomarker and the effectiveness of cognitive behavioural therapy. To facilitate implementation, we subsequently constructed a concise subtype questionnaire and we validated this questionnaire in the second, non-overlapping cohort. FINDINGS: 4322 Netherlands Sleep Registry participants completed at least one of the selected questionnaires, a demographic questionnaire, and an assessment of their Insomnia Severity Index (ISI) between March 2, 2010, and Oct 28, 2016. 2224 (51%) participants had probable insomnia disorder, defined as an ISI score of at least 10, and 2098 (49%) participants with a lower ISI score served as a control group. With a latent class analysis of the questionnaire responses of 2224 participants, we identified five novel insomnia disorder subtypes: highly distressed, moderately distressed but reward sensitive (ie, with intact responses to pleasurable emotions), moderately distressed and reward insensitive, slightly distressed with high reactivity (to their environment and life events), and slightly distressed with low reactivity. In a second, non-overlapping replication sample of 251 new participants who were assessed between June 12, 2017, and Nov 26, 2017, five subtypes were also identified to be optimal. In both the development sample and replication sample, each participant was classified as having only one subtype with high posterior probability (0·91-1·00). In 215 of the original sample of 2224 participants with insomnia who were reassessed 4·8 (SD 1·6) years later (between April 13, 2017, and June 21, 2017), the probability of maintaining their original subtype was 0·87, indicating a high stability of the classification. We found differences between the identified subtypes in developmental trajectories, response to treatment, the presence of an electroencephalogram biomarker, and the risk of depression that was up to five times different between groups, which indicated a clinical relevance of these subtypes. INTERPRETATION: High-dimensional data-driven subtyping of people with insomnia has addressed an unmet need to reduce the heterogeneity of insomnia disorder. Subtyping facilitates identification of the underlying causes of insomnia, development of personalised treatments, and selection of patients with the highest risk of depression for inclusion in trials regarding prevention of depression. FUNDING: European Research Council and Netherlands Organization for Scientific Research.

Multi-target visual search organisation across the lifespan: cancellation task performance in a large and demographically stratified sample of healthy adults.

Accurate tests of cognition are vital in (neuro)psychology. Cancellation tasks are popular tests of attention and executive function, in which participants find and 'cancel' targets among distractors. Despite extensive use in neurological patients, it remains unclear whether demographic variables (that vary among patients) affect cancellation performance. Here, we describe performance in 523 healthy participants of a web-based cancellation task. Age, sex, and level of education did not affect cancellation performance in this sample. We provide norm scores for indices of spatial bias, perseverations, revisits, processing speed, and search organisation. Furthermore, a cluster analysis identified four cognitive profiles among participants, characterised by many omissions (N=18), many revisits (N=18), relatively poor search organisation (N=125), and relatively good search organisation (N=362). Thus, patient scores pertaining to search organisation should be interpreted cautiously: Given the large proportion of healthy individuals with poor search organisation, disorganised search in patients might be pre-existing rather than disorder-related.