Make and Break Eye Contact for Livelier Conversation

News subtitle

A new study helps explain how varying eye contact makes interactions more engaging.

Neuroscience researchers Sophie Wohltjen, Guarini ’21, and Professor Thalia Wheatley
Neuroscience researchers Sophie Wohltjen, Guarini ’22, and Professor Thalia Wheatley. (Photo by Eli Burakian ’00)

Making and breaking eye contact can make a conversation more dynamic and engaging, according to a new neuroscience study.

“Eye contact is really immersive and powerful,” says Sophie Wohltjen, Guarini ’21, a graduate student in psychological and brain sciences and lead author. “When two people are having a conversation, eye contact signals that shared attention is high—that they are in peak synchrony with one another. As eye contact persists, that synchrony then decreases.”

The study, by Wohltjen and Thalia Wheatley, the Lincoln Filene Professor in Human Relations, examined the process known as synchrony, when two speakers’ pupils dilate in sync during moments of “shared attention.” The paper was published in the Proceedings of the National Academy of Sciences.

“In the past, it has been assumed that eye contact creates synchrony, but our findings suggest that it’s not that simple,” says Wheatley, principal investigator of the Dartmouth Social Systems Laboratory. “We make eye contact when we are already in sync, and, if anything, eye contact seems to then help break that synchrony. Eye contact may usefully disrupt synchrony momentarily in order to allow for a new thought or idea.”

The researchers say this decrease is also good because too much synchrony can make a conversation stale. “An engaging conversation requires at times being on the same page and at times saying something new. Eye contact seems to be one way we create a shared space while also allowing space for new ideas,” Wohltjen says.

To examine the relationship between eye contact and pupillary synchrony, pairs of Dartmouth students were brought into the lab. Wearing eye-tracking glasses, each pair was asked to have a 10-minute recorded conversation about whatever they wanted. Afterwards, the researchers asked the two participants to continuously rate how engaged they were.

Illustration of how a single instance of eye contact coincides with pupillary synchrony.
Illustration of how a single instance of eye contact coincides with pupillary synchrony. Figure by Sophie Wohltjen.


The research team looked at how pupillary synchrony increases and decreases around instances of eye contact. The results showed that people make eye contact as pupillary synchrony is at its peak. Pupillary synchrony then immediately decreases, only recovering again once eye contact is broken. The data also demonstrated a correlation between instances of eye contact and higher levels of engagement during the conversation.

“Conversation is a creative act in which people build a shared story from independent voices.” Wheatley adds, “Moments of eye contact seem to signal when we have achieved shared understanding and need to contribute our independent voice.”

The team’s results are consistent with other work, which has illustrated how periodically breaking synchrony can allow for creativity and individual exploration.

Amy Olson