Attribution theory, developed by psychologist Fritz Heider and later expanded by Harold Kelley, examines how people explain behaviour and events. It distinguishes between:
Internal (dispositional) attributions – behaviour explained by personality, motives, or traits.
External (situational) attributions – behaviour explained by context, luck, or environment.
Kelley’s covariation model suggests we look at three factors:
Consensus (do others behave the same way?),
Consistency (does this person usually behave like this?), and
Distinctiveness (does this behaviour happen only in this situation?).
Attribution theory helps us understand everyday judgments, from why someone was late to how juries decide guilt. But it also shows how biases (like the fundamental attribution error) can distort our reasoning.