Thin Slices of Behavior

Definition

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 [Page 990]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.

Impact

Since its introduction to the field of psychology, research on thin-slice judgments has had a distributed impact across social, applied, and cognitive psychology, and it has recently penetrated the popular literature as well. For instance, judgments based on thin slices have been shown to accurately predict the effectiveness of doctors treating patients, the relationship status of opposite-sex dyads (pairs) interacting, judgments of rapport between two persons, courtroom judges' expectations as to a defendant's guilt, and even testosterone levels in males.

Evidence

Recent research on thin-slice judgments has revealed that the accuracy of such judgments is bounded by several factors. Overall, the thin-slice methodology is useful only so long as relevant and valid information can be extracted from a behavioral stream. Factors that influence the accuracy of thin-slice judgments include culture and exposure, individual differences in the ability to decode information accurately, differences in accuracy based on expertise and group membership, and the type of judgment being made. Although, overall, both children and adults who enjoy greater interpersonal success are generally better decoders of nonverbal behavior, individual differences are tempered by cultural and subcultural exposure. Specifically, people are better at accurately judging targets from their own culture and cultures similar to their own than they are those more foreign. Similarly, ingroup benefits exist for groups such as homosexuals, who show an advantage at accurately determining the sexual orientation of others based on thin slices of behavior. More individually, thin-slice judgments can be affected by people's expertise and competency with the particular social context being assessed. Together, these caveats regarding thin slices illustrate how the validity and utility of a thin slice ultimately depends both on the construct being evaluated and on the context within which accuracy is being judged.

For example, although a thin slice may provide valid information regarding an individual's affective state, it may provide entirely invalid information regarding other aspects of that individual, such as future intentions. Much of this variance due to culture and exposure is cogently explained by recent work suggesting the existence of nonverbal dialects and accents that are culturally determined. Exposure to particular dialects and familiarity with cultural norms and constructs contribute to the increased accuracy. Thus, exposure to information about persons based on their group membership and familiarity with the context of evaluation bolsters expertise and accuracy.

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