Definition · Plain-language
Cognitive dissonance
Cognitive dissonance is the psychological discomfort that arises when a person holds two or more contradictory beliefs, values or behaviours simultaneously.
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Festinger’s theory and the $1 vs $20 experiment
Leon Festinger introduced cognitive dissonance theory in 1957, proposing that the mind strives for internal consistency — a state he called consonance. Dissonance arises when two "cognitions" (beliefs, behaviours, values) are psychologically inconsistent. In the landmark Festinger and Carlsmith (1959) experiment, participants who performed a dull task and were paid $1 to tell the next participant it was interesting rated the task as more enjoyable than those paid $20. The $1 group experienced greater dissonance (little external justification for lying) and reduced it by changing their belief about the task. Those paid $20 could attribute their behaviour to the payment, so their beliefs changed less.
Three modes of dissonance reduction
Festinger identified three main strategies for reducing cognitive dissonance. First, changing one of the conflicting cognitions — a smoker who believes smoking causes cancer may quit. Second, adding a new cognition that reconciles the conflict — the smoker may add "but I exercise, which compensates". Third, trivialising the conflict — "everybody dies of something". Post-decision dissonance occurs after making a choice: people reduce residual doubt by increasing appreciation of the chosen option and devaluing the rejected one. Effort justification is a related pattern in which people rate the outcome of a difficult, costly or painful process more highly to justify the effort invested — a mechanism studied by Aronson and Mills (1959).
Applications in persuasion, belief perseverance and health behaviour
Cognitive dissonance is fundamental to understanding why people resist changing their minds when confronted with contrary evidence — a phenomenon called belief perseverance. Motivated reasoning (Kunda 1990) describes how people engage in biased information processing to reach conclusions that relieve dissonance. In health behaviour, dissonance-based interventions use hypocrisy induction to change behaviour: people publicly advocate for a healthy behaviour they do not privately practise, experience dissonance, and then change their behaviour to match their advocacy. This technique has been used effectively to promote condom use (Aronson et al. 1991) and water conservation.
Key facts
At a glance
- Definition: discomfort from holding contradictory beliefs, values or behaviours
- Coined by: Leon Festinger (1957, A Theory of Cognitive Dissonance)
- Festinger & Carlsmith 1959: $1 vs $20 attitude-change experiment
- Three reduction modes: change a cognition, add a reconciling cognition, trivialise
- Effort justification: Aronson & Mills (1959) — costly initiation raises liking
- Belief perseverance: dissonance explains why people resist contrary evidence
- Applied technique: hypocrisy induction to promote health behaviour change
- Related concept: motivated reasoning (Kunda 1990)
Common misconceptions
What people often get wrong
Often heard: Cognitive dissonance means you are confused or indecisive.
Actually: Cognitive dissonance is a specific psychological state — the discomfort of holding contradictory cognitions — and it does not imply confusion. A person may be entirely clear about both their conflicting beliefs and still experience the tension that defines dissonance.
Often heard: People always resolve cognitive dissonance by seeking the truth.
Actually: The theory predicts that people reduce dissonance by whichever means is least costly, which is rarely seeking new evidence. They more often rationalise, trivialise or selectively expose themselves to information that confirms the preferred view — which is why dissonance underlies confirmation bias and motivated reasoning.
Often heard: Cognitive dissonance only applies to moral dilemmas.
Actually: Dissonance arises from any inconsistency between cognitions — including choices between consumer products, beliefs about skill or ability, and factual knowledge. The Festinger & Carlsmith study used a boring task with no moral dimension at all.
Common questions
FAQ
What is the best-known experiment on cognitive dissonance?+
The Festinger and Carlsmith (1959) study is the classic example. Participants paid just $1 to lie about a boring task later rated the task as more enjoyable than those paid $20, because the small payment left them without an external justification for lying and so they changed their attitude toward the task to resolve the dissonance.
How does cognitive dissonance relate to confirmation bias?+
Confirmation bias — the tendency to seek, interpret and recall information that confirms existing beliefs — can be partly explained as a dissonance-reduction strategy. Seeking confirming information and avoiding disconfirming information prevents the psychological discomfort of having to confront contradictory evidence.
Can cognitive dissonance be useful?+
Yes. Hypocrisy-induction interventions deliberately create dissonance to motivate behaviour change: when people publicly advocate for a value they privately violate, the resulting dissonance is resolved by changing their behaviour to match the advocacy. Research by Aronson and colleagues has shown this effective for health and environmental behaviour.
Going deeper
