Excerpts from

Snap Judgements

The Teaching Economist, Issue 19, Fall 2000



What would you think of having someone evaluate your teaching after viewing just a soundless 10-second video clip of you in action? Sounds crazy, doesn't it? But researchers who study "thin slices" of expressive behavior have found that viewers of such a clip feel quite comfortable making an evaluation based on such limited input. What's more, this instant analysis tracks relatively well with students' end-of-term evaluations.


According to
Harvard researchers Nalini Ambady and Robert Rosenthal,
observers who were presented with a 10-second silent video clip of a teacher in a classroom setting had no difficulty rating the teacher on a 15-item checklist of personality traits. Moreover, when the clip was cut to five seconds, the ratings were the same, and they remained the same when the clip was cut to two seconds of videotape.

(From "Snap Judgements" )

These findings were discussed recently by Malcolm Gladwell in The New Yorker, ("The New-Boys Network," 5/29/2000, pp. 68-86). Gladwell admits that this all seems unbelievable, but after he viewed both ten second clips and two seconds clips, he concluded that the eight seconds were "superfluous," noting that "anything beyond the first flash of insight is unnecessary"(p. 70). Snap judgments are just that -- made in a snap.


The next step for Ambady and Rosenthal was to compare these snap judgments with judgements of teacher effectiveness based on end-of-term student evaluations. The correlation was relatively high.

(From "Snap Judgements" )


As Gladwell concludes, "A person watching a two-second silent video clip of a teacher he has never met will reach conclusions about how good that teacher is that are very similar to those of a student who sits in the teacher's class for an entire semester" (p. 70).











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