MONDAY, Jan. 30 (HealthDay News) -- The need for a connection to other people is so powerful that being ignored by a stranger can make someone feel left out, according to a new study.

People need to feel they are part of a group or connected to others in order to be happy, the researchers explained. This sense of belonging can come from joining a club, a friendly neighbor or -- as this study reveals -- even eye contact from a stranger.

In conducting the study, researchers randomly chose people walking on the Purdue University campus in West Lafayette, Ind. A research assistant either looked them in the eye, looked them in the eye and smiled or looked in their general direction but not directly at them. Once they passed the research assistant, the study subjects were asked how connected they felt to others.

The study, published in Psychological Science, found those who had gotten eye contact from the research assistant felt less disconnected than those who were ignored -- even when they didn't get a smile.

"These are people that you don't know, just walking by you, but them looking at you or giving you the air gaze -- looking through you -- seemed to have at least momentary effect," said study co-author Eric Wesselmann of Purdue University in a school news release. "What we find so interesting about this is that now we can further speak to the power of human social connection. It seems to be a very strong phenomenon."

The researchers noted previous studies have shown that being excluded by a group -- even one that they condemn -- can make people feel left out.

More information

The Stanford University Encyclopedia of Philosophy provides more information on friendship.