Attractiveness, Trustworthiness Gauged in Milliseconds

A study by Princeton psychologists has found that judgments about attractiveness and character traits such as trustworthiness and competence are formed in just one-tenth of a second.

In an experiment, subjects were shown different faces for durations of 100 milliseconds to one full second then rated how trustworthy, likable, competent, or attractive each was as well as their confidence in their rating. Researchers found that while the observers' confidence in their increased with longer durations, their initial impressions remained the same.

The study's co-author Alex Todorov suggests that like fear, these split-second responses may be linked to the amygdala:

"The fear response involves the amygdala, a part of the brain that existed in animals for millions of years before the development of the prefrontal cortex, where rational thoughts come from…We imagine trust to be a rather sophisticated response, but our observations indicate that trust might be a case of a high-level judgment being made by a low-level brain structure. Perhaps the signal bypasses the cortex altogether."