Are You “Gazing” at Me? How Others' Gaze Direction and Facial Expression Influence Gaze Perception and Postural Control

In everyday life, interactions between humans are generally modulated by the value attributed to the situation, which partly relies on the partner's behavior. A pleasant or cooperating partner may trigger an approach behavior in the observer, while an unpleasant or threatening partner may trigger an avoidance behavior. In this context, the correct interpretation of other's intentions is crucial to achieve satisfying social interactions. Social cues such as gaze direction and facial expression are both fundamental and interrelated. Typically, whenever gaze direction and facial expression of others communicate the same intention, it enhances both the interlocutor's gaze direction and the perception of facial expressions (i.e., shared signal hypothesis). For instance, an angry face with a direct gaze is perceived as more intense since it represents a threat to the observer. In this study, we propose to examine how the combination of others' gaze direction (direct or deviated) and emotional facial expressions (i.e., happiness, fear, anger, sadness, disgust, and neutrality) influence the observer's gaze perception and postural control. Gaze perception was indexed by the cone of direct gaze (CoDG) referring to the width over which an observer feels someone's gaze is directed at them. A wider CoDG indicates that the observer perceived the face as looking at them over a wider range of gaze directions. Conversely, a narrower CoDG indicates a decrease in the range of gaze directions perceived as direct. Postural control was examined through the center of pressure displacements reflecting postural stability and approach-avoidance tendencies. We also investigated how both gaze perception and postural control may vary according to participants' personality traits and emotional states (e.g., openness, anxiety, etc.). Our results confirmed that gaze perception is influenced by emotional faces: a wider CoDGs was observed with angry and disgusted faces while a narrower CoDG was observed for fearful faces. Furthermore, facial expressions combined with gaze direction influence participants' postural stability but not approach-avoidance behaviors. Results are discussed in the light of the approach-avoidance model, by considering how some personality traits modulate the relation between emotion and posture.

From Social Gaze to Indirect Speech Constructions: How to Induce the Impression That Your Companion Robot Is a Conscious Creature

We implemented different modes of social gaze behavior in our companion robot, F-2, to evaluate the impression of the gaze behaviors on humans in three symmetric communicative situations: (a) the robot telling a story, (b) the person telling a story to the robot, and (c) both parties communicating about objects in the real world while solving a Tangram puzzle. In all the situations the robot localized the human’s eyes and directed its gaze between the human, the environment, and the object of interest in the problem space (if it existed). We examined the balance between different gaze directions as the novel key element to maintaining a feeling of social connection with the robot in humans. We extended the computer model of the robot in order to simulate realistic gaze behavior in the robot and create the impression of the robot changing its internal cognitive states. Other novel results include the implicit, rather than explicit, character of the robot gaze perception for many of our subjects and the role of individual differences, especially the level of emotional intelligence, in terms of human sensitivity to the robotic gaze. Therefore, in this study, we used an iterative approach, extending the applied cognitive architecture in order to simulate the balance between different behavioral reactions and to test it in the experiments. In such a way, we came to a description of the key behavioral cues that suggest to a person that the particular robot can be perceived as an emotional and even conscious creature.

Dysfunctional temporal stages of eye-gaze perception in adults with ADHD: a high-density EEG study

ADHD have been associated with social cognitive impairments across the lifespan, but no studies have specifically addressed the presence of abnormalities in eye-gaze processing in the adult brain. This study investigated the neural basis of eye-gaze perception in adults with ADHD using event-related potentials (ERP). Twenty-three ADHD and 23 controls performed a delayed face-matching task with neutral faces that had either direct or averted gaze. ERPs were classified using microstate analyses. ADHD and controls displayed similar P100 and N170 microstates. ADHD was associated with cluster abnormalities in the attention-sensitive P200 to direct gaze, and in the N250 related to facial recognition. For direct gaze, source localization revealed reduced activity in ADHD for the P200 in the left/midline cerebellum, as well as in a cingulate-occipital network at the N250. These results suggest brain impairments involving eye-gaze decoding in adults with ADHD, suggesting that neural deficits persist across the lifespan.

Applying Hierarchical Bayesian Modeling to Experimental Psychopathology Data: An Introduction and Tutorial

Over the past two decades Bayesian methods have been gaining popularity in many scientific disciplines. However, to this date, they are rarely part of formal graduate statistical training in clinical science. Although Bayesian methods can be an attractive alternative to classical methods for answering certain research questions, they involve a heavy “overhead” (e.g., advanced mathematical methods, complex computations), which pose significant barriers to researchers interested in adding Bayesian methods to their statistical toolbox. To increase the accessibility of Bayesian methods for psychopathology researchers, this paper presents a gentle introduction of the Bayesian inference framework and a tutorial on implementation. We first provide a primer on the key concepts of Bayesian inference and major implementation considerations related to Bayesian estimation. We then demonstrate how to apply hierarchical Bayesian modeling (HBM) to experimental psychopathology data. Using a real dataset collected from two clinical groups (schizophrenia and bipolar disorder) and a healthy comparison sample on a psychophysical gaze perception task, we illustrate how to model individual responses and group differences with probability functions respectful of the presumed underlying data-generating process and the hierarchical nature of the data. We provide the code with explanations and the data used to generate and visualize the results to facilitate learning. Finally, we discuss interpretation of the results in terms of posterior probabilities and compare the results with those obtained using a traditional method.

FUNCTIONAL SPECIFICITY IN EYE GAZE PROCESSING: EVIDENCE FROM DEVELOPMENTAL PROSOPAGNOSIA

<p>The eyes of other people subserve two core functions in human social cognition: gaze perception and face identity recognition. This thesis reports two psychophysical studies that examine the degree of functional specificity between eye gaze processing and face identity processing by testing if various aspects of gaze processing are intact in people with developmental prosopagnosia (DP) – the lifelong inability to recognise face identity. Study 1 investigates spatial integration in eye gaze perception using two tasks. DP and control participants completed one task that measured perception of gaze direction from the two eyes and another that measured the Wollaston illusion (whereby perceived eye gaze is pulled by head rotation; requiring the integration of eye and head direction). Study 2 investigates temporal integration in eye gaze perception using two tasks. The first task measured adaptation effects in eye gaze perception, which reflects sensitivity to gaze direction and its sensory representations. The second task measured serial dependence in gaze perception, which reflects temporal integration of gaze direction and its perceptual stability. Despite their deficits in recognising face identity, DP participants showed normal gaze processing across all studies. These results demonstrate the functional specificity of gaze processing and imply that gaze perception is carried out by dedicated mechanisms not used for processing identity. Our findings align with models of face processing that posit distinct pathways for gaze and identity analysis, and further clarify the selectivity of face processing dysfunctions in developmental prosopagnosia.</p>

FUNCTIONAL SPECIFICITY IN EYE GAZE PROCESSING: EVIDENCE FROM DEVELOPMENTAL PROSOPAGNOSIA

<p>The eyes of other people subserve two core functions in human social cognition: gaze perception and face identity recognition. This thesis reports two psychophysical studies that examine the degree of functional specificity between eye gaze processing and face identity processing by testing if various aspects of gaze processing are intact in people with developmental prosopagnosia (DP) – the lifelong inability to recognise face identity. Study 1 investigates spatial integration in eye gaze perception using two tasks. DP and control participants completed one task that measured perception of gaze direction from the two eyes and another that measured the Wollaston illusion (whereby perceived eye gaze is pulled by head rotation; requiring the integration of eye and head direction). Study 2 investigates temporal integration in eye gaze perception using two tasks. The first task measured adaptation effects in eye gaze perception, which reflects sensitivity to gaze direction and its sensory representations. The second task measured serial dependence in gaze perception, which reflects temporal integration of gaze direction and its perceptual stability. Despite their deficits in recognising face identity, DP participants showed normal gaze processing across all studies. These results demonstrate the functional specificity of gaze processing and imply that gaze perception is carried out by dedicated mechanisms not used for processing identity. Our findings align with models of face processing that posit distinct pathways for gaze and identity analysis, and further clarify the selectivity of face processing dysfunctions in developmental prosopagnosia.</p>

Functional Specificity In Eye Gaze Processing: Evidence From Developmental Prosopagnosia

<p>The eyes of other people subserve two core functions in human social cognition: gaze perception and face identity recognition. This thesis reports two psychophysical studies that examine the degree of functional specificity between eye gaze processing and face identity processing by testing if various aspects of gaze processing are intact in people with developmental prosopagnosia (DP) – the lifelong inability to recognise face identity. Study 1 investigates spatial integration in eye gaze perception using two tasks. DP and control participants completed one task that measured perception of gaze direction from the two eyes and another that measured the Wollaston illusion (whereby perceived eye gaze is pulled by head rotation; requiring the integration of eye and head direction). Study 2 investigates temporal integration in eye gaze perception using two tasks. The first task measured adaptation effects in eye gaze perception, which reflects sensitivity to gaze direction and its sensory representations. The second task measured serial dependence in gaze perception, which reflects temporal integration of gaze direction and its perceptual stability. Despite their deficits in recognising face identity, DP participants showed normal gaze processing across all studies. These results demonstrate the functional specificity of gaze processing and imply that gaze perception is carried out by dedicated mechanisms not used for processing identity. Our findings align with models of face processing that posit distinct pathways for gaze and identity analysis, and further clarify the selectivity of face processing dysfunctions in developmental prosopagnosia.</p>

Aberrant Activation of the Mentalizing Brain System During Eye Gaze Discrimination in Bipolar Disorder

Bipolar disorder (BD) is associated with a range of social cognitive deficits. This study investigated the functioning of the mentalizing brain system in BD probed by an eye gaze perception task during fMRI. Compared with healthy controls (n = 21), BD participants (n = 14) showed reduced preferential activation for self-directed gaze discrimination in the medial prefrontal cortex (mPFC) and temporo-parietal junction (TPJ), which was associated with poorer cognitive and social functioning. Aberrant functions of the mentalizing system should be further investigated as marker of social dysfunction and treatment targets.

Sclera color in humans facilitates gaze perception during daytime and nighttime

Species vary widely in the conspicuousness of their eye morphology and this could influence gaze perception. Eyes with conspicuous morphology can enhance gaze perception while eyes with camouflaged morphology may hinder gaze perception. While evidence suggests that conspicuous eye morphology enhances gaze perception, little is known about how environmental conditions affect this interaction. Thus, we investigated whether environmental light conditions affect gaze perception. Human subjects (Homo sapiens) were instructed to find direct-gaze faces within arrays of averted-gaze faces or to find averted-gaze faces within arrays of directed-gaze faces. The faces were displayed under conditions simulating nighttime or daytime conditions. Furthermore, the faces had naturally-colored sclera (white) or modified sclera (same color as the iris). Participants were fastest and most accurate in detecting faces during the daytime and nighttime conditions when the sclera were naturally-colored. Participants were worst at detecting faces with modified sclera during the nighttime conditions. These results suggest that eyes with conspicuous morphology enhance gaze perception during both daytime and nighttime conditions.