No one likes to be excluded from a group: exclusion can decrease mood, reduce self-esteem and feelings of belonging, and even ultimately lead to negative behavior (e.g., the shootings at Virginia Tech). As a result, we often try to fit in with others in both conscious and automatic ways.
Psychologists Jessica L. Lakin of Drew University, Tanya L. Chartrand of Duke University, and Robert M. Arkin of The Ohio State University studied people's tendency to copy automatically the behaviors of others in order to find out how this mimicry can be used as an affiliation strategy.