It is said first impressions last forever. But what goes in a person's brain when he or she meets someone new is something that has plagued the researchers since time immemorial.
Scientists have now identified the neural systems involved in forming first impressions of others.
Neuroscientists at New York University and Harvard University have shown how people encode social information, and then evaluate it to make initial judgments.
The study was aimed at probing the brain mechanisms that give rise to impressions formed immediately after meeting a new person.
Led by Daniela Schiller, a post-doctoral fellow in NYU's Department of Psychology and its Center for Neural Science, the researchers wanted to explore the process of first impression formation.
Thus, they designed an experiment in which they examined the brain activity, when the participants made initial evaluations of fictional individuals after they were given written profiles of 20 individuals implying different personality traits.
The profiles, presented along with pictures of fictional individuals, included scenarios indicating both positive traits (e.g., intelligent) and negative ones (e.g., lazy) in their depictions.
After reading the profiles, the participants were asked to evaluate how much they liked or disliked each profiled individual.
The impressions varied depending on how much each participant valued the different positive and negative traits conveyed.
During this impression formation period, the participants' brain activity was observed using functional magnetic resonance imaging (fMRI).
On the basis of the participants' ratings, scientists could determine the difference in brain activity when they encountered information that was more, as opposed to less, important in forming the first impression.
The neuroimaging results showed significant activity in two regions of the brain during the encoding of impression-relevant information-the first, the amygdala, is a small structure in the medial temporal lobe that previously has been linked to emotional learning about inanimate objects, as well as social evaluations based on trust or race group.
And the second is the posterior cingulate cortex (PCC), which has been linked to economic decision-making and assigning subjective value to rewards.
The researchers found that these parts of the brain, which are implicated in value processing in a number of domains, showed increased activity when encoding information that was consistent with the impression. br>
"Even when we only briefly encounter others, brain regions that are important in forming evaluations are engaged, resulting in a quick first impression," Nature magazine quoted one of the authors of the study as saying.
Schille concluded: "When encoding everyday social information during a social encounter, these regions sort information based on its personal and subjective significance, and summarize it into an ultimate score, a first impression."
The study appears in the journal Nature Neuroscience.