Not All Outgroups Are Equal: Group Type May Influence Group Effect on Matching Behavior

People tend to match the behaviors and expressions of ingroup members or cooperative others more than outgroup members and competitors. We call this the group effect on interpersonal matching. Our review examines different types of groups to identify when different psychological factors may influence this group effect on matching. Specifically, research demonstrates that affiliation goals increase interpersonal matching; however, other factors such as attention and emotional reaction also appear important. We argue that which of these factors enhance the group effect varies depending on whether group categories are based on minimal, incidental, interdependent, or socially consequential differences. In addition, which expressions (e.g., smiles vs. frowns) are matched varies across group types. To facilitate more directed research, this review describes three key factors and provides a framework to consider which may be involved at different levels of groups. By examining different types of groups, a more complete understanding of how group differences increase or decrease interpersonal matching can be uncovered, providing additional insight into the factors influencing interpersonal matching.