This is how first impressions are made

Scientists have identified the neural systems involved in forming first impressions of others, which show how we encode social information and then evaluate it in making initial judgements.

Each new person we meet may be a source of ambiguous and complex information. However, when encountering someone for the first time, we are often quick to judge whether we like that person or not. Previous research has shown that people make relatively accurate and persistent evaluations based on rapid observations of even less than half a minute.

The study, conducted by the Universities of New York (NYU) and Harvard, sought to investigate the brain mechanisms that give rise to impressions formed immediately after meeting a new person. Accordingly, researchers examined brain activity when these participants made initial evaluations of fictional individuals. They were given written profiles of 20 individuals implying different personality traits.

The profiles, presented along with pictures of these fictional individuals, included scenarios indicating both positive (intelligent) and negative (lazy) traits in their depictions. After reading the profiles, the participants were asked to evaluate how much they liked or disliked each profiled individual.

These impressions varied depending on how much each participant valued the different positive and negative traits conveyed. For instance, if a participant liked intelligence more than they disliked laziness, he or she might form a positive impression. During this impression formation period, participants' brain activity was observed using functional magnetic resonance imaging (fMRI). Based on the participants' ratings, the researchers were able to 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.

The second, the posterior cingulate cortex (PCC), has been linked to economic decision-making and assigning subjective value to rewards. 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.

The study was done in the lab of Elizabeth Phelps, an NYU professor of psychology and neuroscience and a co-author. The study was lead by Daniela Schiller, post-doctoral fellow in NYU department of Psychology, said a NYU release.