First impressions are commonly assumed to be particularly important; instead, judgments of the targets in later situations were more strongly associated with overall impressions, indicating an acquaintance effect

There Is No Primacy Effect in Interpersonal Perception: A Series of Preregistered Analyses Using Judgments of Actual Behavior. Anne Wiedenroth, Nele M. Wessels, Daniel Leising. Social Psychological and Personality Science, November 13, 2020. https://doi.org/10.1177/1948550620969279

Rolf Degen's take: https://twitter.com/DegenRolf/status/1327527434909065217

Abstract: First impressions are commonly assumed to be particularly important: Information about a person that we obtain early on may shape our overall impression of that person more strongly than information obtained later. In contrast to previous research, the present series of preregistered analyses uses actual person judgment data to investigate this so-called primacy effect: Perceivers (N = 1,395) judged the videotaped behavior of target persons (N = 200) in 10 different situations. Separate subsamples of about 200 perceivers each were used in moving from exploratory to increasingly confirmatory analyses. Contrary to our expectations, no primacy effect was found. Instead, judgments of the targets in later situations were more strongly associated with overall impressions, indicating an acquaintance effect. Relying on early information seems unreasonable when more comprehensive information is readily available. Early information may, however, affect perceivers’ behavioral reactions to the targets and thus their future interactions, if such interactions are possible.

Keywords: primacy effect, order effects, impression formation, behavior observation, personality judgment