The organizational principles of impression formation.

Trait impressions about others are a fundamental tool to navigate the rich social environment and yet a unitary model of its organizational principles is still lacking. The statistical properties of impression formation observed in previous studies are akin to processes that govern information encoding and storage in memory, suggesting similar cognitive and computational mechanisms. Here, in 2,780 participants, impression formation has been formalized with a computational model representing three organizational principles of memory (temporal, semantic and valence-related). The model specifically captured two main patterns of impression formation: (1) a negative valence effect that makes negative impressions loom longer than positive ones; (2) an interaction effect between the temporal and valence content that endorses more negative impressions when negative information is met first. This work shows that mechanisms of information encoding, storage and retrieval interact in ways that explain biased impression formation about social partners, thereby providing quantitative evidence for those mechanisms in individuals' impressions of others' social qualities. We discuss the implications of these results for social impressions in different, real-world contexts, and suggest how the proposed model might be extended to capture other kinds of effects, from negativity bias and pessimism to social discrimination.