Remembering first impressions: Effects of intentionality and diagnosticity on subsequent memory

People rely on first impressions every day as an important tool to interpret social behavior. While research is beginning
to reveal the neural underpinnings of first impressions, particularly through understanding the role of dorsal medial prefrontal
cortex (dmPFC), little is known about the way in which first impressions are encoded into memory. This is surprising because
first impressions are relevant from a social perspective for future interactions, requiring that they be transferred to memory.
The present study used a subsequent-memory paradigm to test the conditions under which the dmPFC is implicated in the encoding
of first impressions. We found that intentionally forming impressions engages the dmPFC more than does incidentally forming
impressions, and that this engagement supports the encoding of remembered impressions. In addition, we found that diagnostic
information, which more readily lends itself to forming trait impressions, engages the dmPFC more than does neutral information.
These results indicate that the neural system subserving memory for impressions is sensitive to consciously formed impressions.
The results also suggest a distinction between a social memory system and other explicit memory systems governed by the medial
temporal lobes.