Situationism is a psychological theory that emphasizes the influence of situational factors over individual traits in determining behavior. It suggests that people's actions are often shaped more by their environment and context than by their personal characteristics. This perspective challenges the idea that behavior is primarily driven by stable personality traits. The theory gained prominence through the work of psychologists like Philip Zimbardo, particularly with the Stanford prison experiment, which illustrated how ordinary individuals could engage in extreme behaviors based on their roles and surroundings. Situationism highlights the importance of understanding the context in which behavior occurs to better comprehend human actions.