Self-perception theory
We infer our own attitudes by observing how we behave, as an outside observer would.
What it means
Self-perception theory proposes that when internal cues are weak or ambiguous, people deduce their own attitudes, preferences, and emotions by observing their own behavior and the context in which it occurs, much as an outside observer would infer them. The mechanism is inferential rather than introspective: rather than reading off a pre-existing internal state, the person reasons 'I am doing this freely, so I must like it (or believe it).' Bem advanced the theory as a parsimonious alternative to cognitive dissonance, arguing that attitude change after counter-attitudinal behavior need not involve aversive tension but can be simple self-inference, and the two accounts are now seen as applying in different conditions — dissonance when behavior clearly contradicts a salient prior attitude, self-perception when the prior attitude is weak or absent. It also offers an account of the overjustification effect and of why small commitments shift later behavior, as in the foot-in-the-door technique. It matters because it implies that getting people to act can change what they believe, and that we are often surprisingly uncertain about our own attitudes until we watch ourselves.
Examples
Asked to advocate a position, people come to believe it more strongly — they infer their attitude from hearing themselves argue for it.
Agreeing to put a small charity sticker in your window makes you likelier to donate later: you watch yourself support the cause and conclude you must be the sort who cares.
Someone who cycles to work only because the car is in the shop notices six weeks on that he keeps choosing the bike — and starts calling himself a cyclist.
First described in Daryl Bem (1972).