These are data from the two primary dependent measures from my ESRC grant examining how novel lab-based stereotypes form via a process of cumulative cultural evolution. The data were collected from undergraduate participants who were tested individually. Each participant was a single 'generation' within a 'diffusion chain' of seven generations. Participants were asked to try and learn some information about some novel social targets. The responses each participant produced during a test phase were used as the learning materials for the next participant (i.e., generation). The dependent measures of interest were the accuracy with which people completed the task and the amount of structure that was present in their responses. We were interested in whether a stereotype-like categorical structure would develop as information was passed down the chains and whether this would result in associated increases in accuracy.While much is known about the substantial influence stereotypes exert on our lives, relatively little is known about how stereotypes form. One possibility is that stereotypes form unintentionally over time when information is passed from person to person. The current research will examine this possibility by utilising a diffusion chain methodology. The first participant in a chain will attempt to learn and recall information (ie, personality traits) randomly assigned to novel target individuals; the recollections of this participant will then be used as the learning materials for the subsequent participant - this process continues to form a chain. It is predicted that the merest hint of pattern in the memories of one participant will be unconsciously detected and inadvertently amplified in the recollections of the next participant. Thus, as it passes from one person to the next, a task that is initially random and requires remembering multiple traits associated with many different individuals will become increasingly structured and learnable. This structure will continue to accrue over time until a stable, easily learnable relationship exists between category membership and associated information - until a stereotype has formed.

Lab-based experimental psychology using a diffusion chain methodology. The data were collected on personal computers. A sample of undergraduate students was recruited to take part in the experiments.