How stereotypes develop from memory limitations and second-hand knowledge

We investigated the evolution of stereotypes in three experiments using the social transmission paradigm (Martin et al., 2014). Participants studied “aliens” that could be categorized by perceptible features (shape and color). Aliens were studied with six individual personality attributes (e.g., serious, arrogant) that were initially randomly assigned. The attributes as recalled by a participant were given to the next participant for study, so that information was transmitted in chains from one generation of participants to the next. Experiment 1 (N = 140 university students) tested an adjusted version of the transmission paradigm, in which all test items had been studied, for subsequent use in Experiments 2 (N = 160 university students) and 3 (N = 164 university students). We replicated previous results: Although each chain started with random attributes assigned to aliens, over the course of four generations recall became easier and more stereotypical. In Experiments 2 and 3 we introduced second-hand knowledge (explicit stereotypes) about groups of aliens before or after participants studied the individual aliens, followed by the memory test. Again, stereotypes developed. Moreover, these stereotypes increasingly aligned with the explicit stereotypes in later generations, even though the stereotypes were not true initially. These effects occurred both for participants who saw explicit stereotypes before and those who saw them after they studied the individual aliens. We conclude that incomplete memory and second-hand knowledge contribute to stereotype formation.