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The threat capture hypothesis states that threatening stimuli are automatically processed with higher priority than non-threatening stimuli, irrespective of observer intentions or focus of attention. We evaluated the threat capture hypothesis with respect to the early perceptual stages of face processing. We focused on an electrophysiological marker of face processing (the lateralized N170) in response to neutral, happy, and angry facial expressions displayed in competition with a non-face stimulus (a house). We evaluated how effects of facial expression on the lateralized N170 were modulated by task demands. In the pixel task, participants were required to identify the gender of the face, which made the face task-relevant and entailed structural encoding of the face stimulus. In the pixel task, participants identified the location of a missing pixel in the fixation cross, which made the face task-irrelevant and placed it outside the focus of attention. When faces were relevant, the lateralized N170 to angry faces was enhanced compared to happy and neutral faces. When faces were irrelevant, facial expression had no effect. These results reveal the critical role of task demands on the preference for threatening faces, indicating that top-down, voluntary processing modulates the prioritization of threat. [ABSTRACT FROM AUTHOR]

The distribution of retino-tectal projections is dissimilar depending on whether the receptors are situated in the nasal and temporal visual hemiretinas. Indeed, it has been claimed that the superior colliculus receives a greater proportion of its input from the temporal visual hemifield (nasal hemi-retina) relative to the nasal hemifield (temporal hemi-retina). In order to investigate whether these subcortical projections influence face processing, we investigated the early cortical ERP responses to faces and houses presented in the temporal and nasal retinas using monocular viewing. Neutral or fearful faces were presented concurrently with houses on either side of a central fixation cross, while participants were asked to discriminate changes in luminance at the center. Results showed that the lateralized N170, computed as the contralateral-ipsilateral electrode difference, was greater for faces appearing in the nasal relative to the temporal visual hemifield. This was due to a greater ipsilateral N170 for temporal relative to nasal presentations. By contrast, no difference was found across emotional expressions. The enhanced ERP response to faces appearing in the temporal visual field, suggests that the retinotectal pathway modulates cortical processing, most likely through activation of a colliculo-pulvino-amygdalar pathway, with subsequent back-projections from the amygdala to visual cortical regions. However, unattended facial expressions do not seem to modulate the response, at least at these angles of eccentricity. [ABSTRACT FROM AUTHOR]

Gaze direction is an important social signal for human beings. Beside the role of gaze in attention orienting, direct gaze (that is, gaze directed toward an observer) is a highly relevant biological stimulus that elicits attention capture and increases face encoding. Brain imaging studies have emphasized the role of the superior temporal sulcus (STS) in the coding of gaze direction and in the integration of gaze and head cues of social attention. The dynamics of the processing and integration of these cues remains, however, unclear. In order to address this question, we used deviated and frontal faces with averted and direct gaze in a combined electro- and magneto- encephalography (EEG–MEG) study. We showed distinct effects of gaze direction on the N170 and M170 responses. There was an interaction between gaze direction and head orientation between 134 and 162 ms in MEG and a main effect of gaze direction between 171 and 186 ms in EEG. These effects involved the posterior and anterior regions of the STS respectively. Both effects also emphasized the sensitivity to direct gaze. These data highlight the central role of the STS in gaze processing. [ABSTRACT FROM AUTHOR]

Direction of another person's eye gaze provides crucial information about their attention and intentions, which is essential for an effective social interaction. Event-related potential (ERP) measures offer precise temporal tracking of neural processes related to gaze perception. While the sensitivity of the ERP component N170 to face processing is principally agreed, the research on gaze direction effect on this component is thus far inconsistent. Here, we systematically reviewed literature on the sensitivity of N170 to gaze direction. We analysed if four factors, known to affect the face N170 (i.e., emotion, face orientation, task demand, and stimuli motion), were modulated by gaze direction. N170 sensitivity to gaze was reported the most in the studies that involved deviated faces, dynamic stimuli, and that used explicit tasks directly related to gaze or face processing. The present review provides a much-needed summary of the literature to date, highlighting the complexity of the effect of gaze direction on the N170 component, and the need of systematic studies investigating the combination of these factors. • Perception of gaze direction provides crucial attentional and intentional cues for social interactions. • Electroencephalography allows seizing neural mechanisms related to gaze direction processing with high temporal resolution. • Over last two decades reports of studies on gaze direction effect on N170 component are very inconsistent. • Reports were the most coherent across studies using dynamic face stimuli and tasks with explicit processing of the eye region. • Consistent reporting of methodological details and studies systematically manipulating the affecting factors are required. [ABSTRACT FROM AUTHOR]