Thin-slice judgement

Two researchers showed people extraordinarily brief, silent video clips of teachers, just a few seconds, no sound, and asked them to rate the teacher on qualities like warmth, competence, and confidence. Then they compared those snap ratings to the evaluations those same teachers received from students at the end of a full semester. The judgements from a few silent seconds correlated strongly with the considered opinion of students who had spent months in the class. People formed impressions very quickly, and those impressions closely predicted the ratings of people who had seen far more. The finding became famous as evidence for the power of thin slices, the idea that we read people accurately in seconds. Later work has been more cautious: the effect is real but the famous strong number came from small samples, and larger analyses find it more modest than the headline suggested.

You form a strong impression of a person within seconds, and that impression is powerful enough to shape everything that follows, whether or not it is accurate. That is the real danger, not that snap judgements are always wrong, but that they are sticky. Once formed in the first seconds of an interview, your impression steers which questions you ask and how you read the answers, so the rest of the conversation tends to confirm it. Knowing your verdict is largely written in the opening moments, deliberately hold it loosely, and force yourself to look for evidence against your first read, because it formed before you knew anything real.

Source: Ambady and Rosenthal, 1993. Later meta-analytic work finds smaller effects than the original. The popular case for rapid judgement: Malcolm Gladwell, Blink, 2005.

Blink

Malcolm Gladwell, 2005

The case for rapid judgement, worth reading alongside its many documented failures.