Eye contact
Eye contact is hard to maintain when you have to search for the right word to use. shiranai / Flickr

Maintaining eye contact is a distraction that our brains just can't handle when we're searching for the right words, a new study finds.

There is interference in the brain between focusing on someone else's face and the process of finding the best words to express ourselves, according to the study published in the journal Cognition. This is why we commonly avert our eyes from someone's face even when we are talking to them, the researchers say.

The cognitive resources used by both processes are related, the scientists at Kyoto University in Japan say. This results in competition between the process of retrieving and selecting words, and maintaining eye contact when we try to it all at once.

The researchers compared videos of people speaking while maintaining eye contact with videos of people who averted their eyes. They found that people were slower to find the right words when directing their gaze at another person.

However, the effect was only pronounced when searching for less obvious words, they found.

For instance, connecting the word 'ball' to the word 'bounce' is not likely to use up too much of your cognitive resources as the association is close. However when given the word 'phone', there are more immediate options: call, answer or talk, for instance.

Searching through these and picking the right one might require you to look away from the person you're talking to in order to give yourself a bit of mental space, the researchers found.

"The results support the hypothesis that eye contact shares domain-general cognitive resource with verb generation," the authors write in the paper.

"This further indicates that a full understanding of functional and dysfunctional communication must consider the interaction and interference of verbal and non-verbal channels."