How long does it take us to make up our mind about someone?


About 100 milliseconds. Seriously:

People often draw trait inferences from the facial appearance of other people. We investigated the minimal conditions under which people make such inferences. In five experiments, each focusing on a specific trait judgment, we manipulated the exposure time of unfamiliar faces. Judgments made after a 100-ms exposure correlated highly with judgments made in the absence of time constraints, suggesting that this exposure time was sufficient for participants to form an impression. In fact, for all judgments-attractiveness, likeability, trustworthiness, competence, and aggressiveness-increased exposure time did not significantly increase the correlations. When exposure time increased from 100 to 500 ms, participants’ judgments became more negative, response times for judgments decreased, and confidence in judgments increased. When exposure time increased from 500 to 1,000 ms, trait judgments and response times did not change significantly (with one exception), but confidence increased for some of the judgments; this result suggests that additional time may simply boost confidence in judgments. However, increased exposure time led to more differentiated person impressions.

Source: “First impressions: making up your mind after a 100-ms exposure to a face.” from Psychol Sci. 2006 Jul;17(7):592-8.

What’s even more interesting is how often we’re right about what we surmise from quick judgments about people’s faces. I’ve written about this in Wired Magazine; we’re right more often than not when evaluating people’s conscientiousness, extraversion and trustworthiness based only on a glance at their mug.

A look at someone’s face can also give you clues on many many other things such as how orgasmic a woman is and whether a CEO will lead a company to success.

I find the whole area of thin-slicing (“the ability to find patterns in events based only on “thin slices,” or narrow windows, of experience.”) fascinating. If you want to learn more about it, check out Malcolm Gladwell’s #1 bestseller Blink: The Power of Thinking Without Thinking.

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