The article says that because there's a strong correlation between ratings by people who have only seen 30 second clips and ratings by people who have been in class all semester, that first impressions are very accurate.

The alternative explanation is that we make snap judgments easily, and have a hard time letting go of them even after several months.

If the judgments are about whether we're going to like something, is your alternative explanation actually even different?

Maybe it's worse with harvard undergraduates than "normal people", because they are better at recalling and rationalizing their decisions.

Not sure why the result is so surprising. If you are warm and confident, you are likely to appear as such in a 30 second video. If not, then not so likely. I'm not sure of all the criteria one would use to judge professional, but surely dress and appearance play a large part, and you can judge that just from a still image.

Competence is certainly harder to tell from a short clip, but I think people's impressions, both long and short term, for competence are a function of the more immediately apparent characteristics. If you wear an inside out t-shirt and have dishevelled hair, your competence rating is probably going to take a hit, even after a long term exposure.

It's important to note that the study didn't actually measure objective values such as competence, rather it measured perception (and student's perception, at that) of such traits.

I'm curious as to why the author was impressed that in three 30 second samples, a student's perception of traits correlated with students who had more time (albeit several months) to develop that perception. Did they think that the instructor would act noticeably different? Or, did they think that for some reason the several month experience would develop more than perception, and actual knowledge?

Now, for a more interesting study, I'd be interested in seeing how well the student's perception correlated to a professional psychological profile, analytical review, and other _objective_ measurements of the teacher.

Headline: s/It's/Its/

ech, thanks

Isn't this just called "experience"? When you've been through 13-16 years of schooling, you learn what good teachers look (act, talk, stand, etc.) like.