Eye contact and facial expressions provide important social and emotional information. People, perhaps without consciously doing so, probe each other’s eyes and faces for positive or negative mood signs. In some contexts, the meeting of eyes arouses strong emotions.
Mutual eye contact that signals attraction initially begins as a brief glance and progresses into a repeated volleying of eye contact, according to Beverly Palmer, Ph.D. and professor of psychology at California State University, Dominguez Hills.
In the process of civil inattention strangers in close proximity, such as a crowd, avoid eye contact in order to help maintain their privacy.
When two or more individuals talk, the person that talks is used to being looked at. Therefore, making eye contact is making other people expect conversation.
Eye aversion and mental processing
A study by Phelps, Doherty-Sneddon, and Warnock concluded that children who avoid eye contact while considering their responses to questions are more likely to answer correctly than children who maintain eye contact. According to Doherty-Sneddon:
"Looking at faces is quite mentally demanding. We get useful information from the face when listening to someone, but human faces are very stimulating and all this takes processing. So when we are trying to concentrate and process something else that’s mentally demanding, it’s unhelpful to look at faces."
Contrariwise, Doherty-Sneddon suggests that a blank stare indicates a lack of understanding.