Understanding how the brain interprets other’s gazes

ERP analysis and task impact on the perception timing of gaze direction.

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Understanding where others are looking is crucial in everyday interactions. Our brain quickly interpret gaze direction to communicate effectively. A recent study in NeuroImage by the University of Geneva pinpointed exactly when our brains detect gaze direction. This insight is crucial for understanding conditions like autism and may help in Alzheimer’s therapy.

Since birth, faces have been our most common visual stimuli. Our brains are skilled at remembering faces and understanding their signals. Direct eye contact signals social interest while avoiding eye contact sends a different message. Previous studies often focused only on the eyes, ignoring factors like head position.

At UNIGE, researchers used 3D avatars to test how people perceive head and gaze directions. Participants identified head orientation in one task, while in another, they focused on eye direction. Using electroencephalogram (EEG) readings, the team found they could decode these processes independently.

Image showing The brain first perceives the more global visual cues, i.e. the orientation of the head, from 20 milliseconds onwards, before focusing on the more local information, i.e. the eyes, from 140 milliseconds onwards.
The brain first perceives the more global visual cues, i.e. the orientation of the head, from 20 milliseconds onwards, before focusing on the more local information, i.e. the eyes, from 140 milliseconds onwards. credit: UNIGE.

The study revealed that the brain processes head orientation first, starting at 20 milliseconds, followed by eye direction at 140 milliseconds. This hierarchy helps integrate both cues for accurate gaze perception, as explained by Domilė Tautvydaitė, a postdoctoral fellow at UNIGE’s Faculty of Psychology and Educational Sciences.

The study found that people were much better at understanding gaze direction when specifically asked to focus on it. This shows that our ability to perceive gaze is influenced by what we’re paying attention to in social situations. According to Nicolas Burra from UNIGE, when people are actively engaged socially, they’re quicker and more accurate at interpreting others’ intentions.

The research used advanced methods combining EEG and machine learning to predict gaze and head direction perception with high precision, even before participants were consciously aware. Burra notes that this method significantly advances understanding of these cognitive processes.

In autism spectrum disorders, people may struggle to interpret gaze direction and often avoid eye contact. Similarly, Alzheimer’s disease can impair memory and lead to social withdrawal, affecting relationships. Understanding how the brain detects gaze direction is crucial for addressing these challenges.

This study’s findings and methods could help diagnose autism earlier in children. In Alzheimer’s, difficulty recognizing faces, even of loved ones, is a prominent symptom. Research at UNIGE’s ESClab and McGill University aims to deepen our understanding of these neural processes in social interactions and memory, offering potential insights for future studies.

Journal reference:

  1. Domilė Tautvydaitė, Nicolas Burra, et al., The Timing of Gaze Direction Perception: ERP Decoding and Task Modulation. NeuroImage. DOI: 10.1016/j.neuroimage.2024.120659.

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