Encyclopedia of Social Psychology

Thin slices of behavior is a term coined by Nalini Ambady and Robert Rosenthal in their study examining the accurate judgments of teacher effectiveness. They discovered that very brief (10-second and even 2-second) clips of dynamic silent video clips provided sufficient information for naive raters to evaluate a teacher’s effectiveness in high correlation with students’ final course ratings of their instructors. Distinctively, thin slices are thus defined as brief excerpts of expressive behavior, sampled from the behavioral stream, that contain dynamic information and are less than 5 minutes long. Thin slices can be sampled from any available channel of communication, including the face, the body, speech, the voice, transcripts, or combinations of all of these. Hence, static images (e.g., photographs) and larger chunks of dynamic behaviors would not qualify as thin slices. Thin slices retain much, if not most, of the information encoded via dynamic, fluid behavior while reducing or sometimes eliminating the information encoded within the ongoing verbal stream, the past history of targets, and the global, comprehensive context within which the behavior is taking place.