The human brain can judge the apparent trustworthiness of a face from a glimpse so fleeting, the person has no idea they have seen it, scientists claim.
Researchers in the US found that brain activity changed in response to how trustworthy a face appeared to be when the face in question had not been consciously perceived. Scientists made the surprise discovery during a series of experiments that were designed to shed light on the the neural processes that underpin the snap judgments people make about others. The findings suggest that parts of our brains are doing more complex subconscious processing of the outside world than many researchers thought. Jonathan Freeman at New York University said the results built on previous work that shows “we form spontaneous judgments of other people that can be largely outside awareness.”
The study focused on the activity of the amygdala, a small almond-shaped region deep inside the brain. The amygdala is intimately involved with processing strong emotions, such as fear. Its central nucleus sends out the signals responsible for the famous and evolutionarily crucial “fight-or-flight” response.
“The social cues for trustworthiness are considerably more subtle and complex than a simple, fearful expression on a clearly emotional face. It suggests that the amygdala’s processing of social cues outside awareness may be more extensive than we thought ,” Freeman said.