Prolonged eye contact synchronizes brain activity between two people, according to a new study at the National Institute of Physiological Science (NIPS). This synchronicity is crucial in establishing and facilitating our face-to-face social interactions.
Eye contact is fundamental in most personal interactions. In most cultures, we are taught from a young age to maintain eye contact when we speak to another person. In fact, not making eye contact may be considered impolite, and can even risk losing the other party’s attention.
The mechanisms of visual attention through eye contact between two people (mutual gaze), and toward a third person or an object (joint attention), have been extensively studied. However, what is actually going on in the brain during this time has remained unclear.
To further understand this topic, the researchers enrolled 96 volunteers who did not know each other. They then conducted a series of tests to investigate the brain activity during situations with sustained eye contact.
Three sets of experiments were conducted in a two-day period. Participants were paired with different partners and instructed to hold each other’s gaze under various conditions. The researchers used functional magnetic resonance imagining to monitor the brain activity that took place during each gaze.
“We expected that eye-blink synchronization would be a sign of shared attention when performing a task requiring joint attention, and the shared attention would be retained as a social memory,” said Takahiko Koike, the study’s first author.
The researchers also hypothesized that the right inferior frontal gyrus (IFG) in the brain would be activated by both the initiator and the respondent to the gaze.
Indeed, the researchers detected synchronization of eye-blinks, as well as greater inter-brain synchronization in the IFG, in both participants when eye contact was established. Compared with findings from previous studies, these outcomes show that synchronization of eye-blinks is not attributable to a common activity, but rather to mutual gaze.
The findings indicate that mutual eye contact might be a crucial component for human face-to-face social interactions, given its potential to bind two individuals into a singular connected system. The researchers would like to conduct further investigation to truly understand what is at work behind interpersonal communications.
“Based on the enhancement of behavioral and neural synchronization during mutual gaze, we now know that shared attention is hard to establish without eye contact,” said Norihiro Sadato, senior author of the study.
“Further investigation into the workings of eye contact may reveal the specific functional roles of neural synchronization between people.”