Glossary
Truth Bias
What is truth bias?
Truth bias is a tendency to judge communication as honest, often unless something prompts suspicion. It helps ordinary communication proceed, while also leaving room for deception.
How truth-default theory explains it
Levine's 2022 account proposes that people often accept messages without actively deciding whether they are true. Suspicion can interrupt that default. Beliefs, social context, and repeated messages can affect acceptance.
An everyday example
Imagine a colleague says, “The meeting has moved to three o'clock.” You change your plans without first investigating whether the colleague is honest. Then a message from the organizer still lists two o'clock. That conflict gives you a reason to check the calendar or ask the organizer. Suspicion starts an investigation; it does not prove that the colleague lied. They may simply be mistaken.
Truth bias and accuracy
If most messages are truthful, a tendency to believe them is not necessarily inaccurate. A response tendency and the ability to distinguish truths from lies are different measures.
Suppose, in a hypothetical set of 100 messages, 90 are true and 10 are deliberate lies. Someone who labels every message truthful is correct 90 times but detects none of the lies. Their high overall accuracy comes from the messages' composition, not from an ability to distinguish honesty from deception. This separates a tendency to believe from successful discrimination.
Why it matters
Use concrete evidence when truth matters. Presumed signs of dishonesty should not substitute for checking the claim.
The illusory truth effect is related but different: repetition can make a statement seem more credible.