The current research examined how people form context-based trait impressions and why some of these impressions are stronger than others. This research drew from principles of attention theory (Kruschke, 1996, 2001) in order to account for the processes underlying impression formation in context According to attention theory, the traits expressed by an individual target person in a rarely occurring context should be more strongly associated with that context than the traits expressed in a commonly occurring context are associated with the common context That is, people form stronger impressions of others' behavior in rare compared to common contexts. Four experiments provide support for these predictions. The current study is one of the first to examine the cognitive mechanisms by which perceivers form trait impressions of individuals across different contexts and to explain why some of these impressions are stronger than others. Implications of the nature of these impression formation processes are discussed. (C) 2016 Elsevier Inc All rights reserved.