First let’s define the difference between a first impression, which is based on potentially up to 10,000 cues in less than a minute of interaction with another person, and formed in the limbic system and therefore has a high degree of accuracy, ( 70 percent or higher ) and a stereotype which is based on past experiences, radical, ethnic, socioeconomic and other learned prejudicial information and formed in the neocortex and has a low degree of accuracy less than 30 percent.
A first impression is typically accessing credibility, likeability, attractiveness, and power. First impressions help us asses if someone is safe to approach. So, for example, Attractiveness may seem a stereotypical assessment, however facial and body symmetry and other cues such as shiny hair and clear skin can also indicate overall health so someone is safer to approach and genetically healthy, (approach because they would make healthy babies.)
First impressions happen very quickly. Harvard teaching fellows were videotaped and a 10-second silent piece of that video was shown to outside observers, who were asked to rate the teachers on a 15-item checklist of personality traits. Even when Ambady cut the video back to 5 seconds--even to 2 seconds--the ratings remained the same. All the important stuff happened, apparently, in the first 2 seconds.
Here's the scariest part: Ambady and Rosenthal discovered that a person's conclusions after watching that 2-second video clip of a teacher he has never met are very similar to the conclusions reached by classroom participants after an entire semester's exposure.
