Attribution theory proposes that people make causal explanations for behaviors and events, classifying them as either internal/dispositional (due to traits and abilities) or external/situational (due to outside factors). However, people are subject to attribution biases like the fundamental attribution error of overemphasizing internal causes for others' behaviors. Kelley's covariation model examines consensus, distinctiveness, and consistency of behaviors to determine whether to attribute them internally or externally. People also differ in attributional style, with optimists explaining negatives externally and positives internally versus pessimists.