In regular social encounters, the gaze is crucial. Our ability to communicate instantly is dependent on the brain’s ability to recognize and decipher other people’s gaze directions. What elements affect the way our brain determines gaze direction?
A team from the University of Geneva (UNIGE) was able to pinpoint the precise instant at which the direction of gaze is identified with previously unheard-of precision in a study that was published in the journal NeuroImage. These discoveries greatly advance our knowledge of autism spectrum illnesses and may present therapeutic opportunities for Alzheimer’s patients.
The most frequent and reliable visual cues we are exposed to from the moment of our birth are the faces of people. The ability to memorize, identify, and decipher facial expressions is a developed brain function. Direct eye contact, for example, indicates a desire to communicate socially, but avoiding eye contact sends the opposite message.
But how quickly does our brain register other people’s gaze? Many studies have been conducted on this subject. Still, most of the articles that are now in print ignore additional elements, such as head orientation, in favor of focusing on the study of the eye region alone.
Analyzing gaze in the brain
Participants in the study were shown 3D avatars by a UNIGE team, each with a unique head and gaze orientation. In task one, participants had to point out the head’s orientation, and in task two, they had to point out the eyes’ direction.
Through electroencephalogram analysis, the research team has found that these two processes may be reliably deciphered apart from one another.
The experiment also shows how these two pieces of information are processed in a particular hierarchy. First, the brain registers the more global visual cues, such as the head’s orientation, from 20 milliseconds onward, and then it focuses on the more local information, such as the eyes, from 140 milliseconds onward,” says the study’s first author, Domilė Tautvydaitė, an associate researcher and postdoctoral fellow at the UNIGE, Faculty of Psychology and Educational Sciences.
“This hierarchical organization then allows for integration of eye region and head orientation information, to ensure the accurate and effective judgment of gaze direction.”
The study also shows that when participants were explicitly instructed to focus on the gaze of the presented faces, the decoding of gaze direction was considerably more accurate. This indicates that the gaze is perceived and understood differently depending on the task setting.
“In daily life, these findings demonstrate that individuals who are actively participating in a’social mode,’ are more adept and quick at discerning the intentions of others,” says Nicolas Burra, the study’s principal investigator and senior lecturer at the Faculty of Psychology and Educational Sciences at UNIGE.
A cutting-edge method
The technique yields remarkably precise outcomes for these two systems. Through the integration of machine-learning approaches with electroencephalography (EEG) measurement of neural activity, the research team was able to predict head direction and gaze decoding before the subjects even realized it was happening.
“This method represents a significant technical innovation in the field, allowing for a much more precise analysis than it was previously attainable,” says Nicolas Burra.
Eye contact may be avoided by those with autism spectrum disorders as their ability to interpret this information may be compromised. This also holds true for Alzheimer’s disease, when memory loss damages a person’s social interactions and frequently results in social disengagement as the condition progresses. Therefore, knowledge of the brain mechanisms behind gaze direction detection is crucial.
The study’s findings and methodology have a tangible impact on children’s early diagnosis of autism spectrum disorders. The inability to recognize faces, especially those of family members, is one of the most noticeable signs of Alzheimer’s disease as it advances.
Thus, our work opens the door to a deeper comprehension of the brain mechanisms associated with decreased social interaction and face memory—a topic that Dr. Tautvydaitė of McGill University in Canada is presently investigating.
In this area, the ESClab laboratory study at UNIGE will carry out further research by examining these processes in real-world social interactions.
