The role of mental state understanding in distinctively human cumulative cultural evolution

Abstract

This thesis aimed to contribute to the existing literature exploring distinctively human cognitive mechanisms. Specifically, the aim was to investigate whether, and how, the distinctively human propensity for understanding the mental states of others (referred to commonly in the literature as ‘theory of mind’) facilitates cumulative cultural evolution. The general methodology used throughout this thesis involved grid search tasks in which participants searched for stimuli using vicarious information generated from a participant who had already attempted the same grid search. The first experimental chapter in this thesis explored the suitability of the grid search task for capturing search behaviour in response to vicarious information about search outcomes. The second experimental chapter explored adult transmission behaviour, and whether small amounts of intentionally produced information could facilitate cumulative culture relative to small amounts of inadvertently produced information. This methodology was extended to a sample of children in Chapter 4 in order to assess whether the ability to intentionally select beneficial information to facilitate cumulative culture increases with age. The final experimental chapter explored a similar task context, but instead of manipulating downward transmissions, manipulated upward transmissions to assess whether feedback from successors influences the quality of information sent by the predecessor. Together these studies explored the ability (which may be distinctive to humans) to tailor transmitted information to the needs of a specific receiver in order to best facilitate the retention of beneficial knowledge. This thesis found that the sharing of intentionally selected knowledge is sufficient for generating cumulative cultural evolution over generations, relative to circumstances where only inadvertent cues about a predecessor’s performance is available. Furthermore, the developmental trajectory found in this capacity suggests that it may be supported by distinctively human cognitive mechanisms. We believe that capacities for understanding others’ minds were responsible for the successful performance of the adults and older children in the transmission chain tasks, and we argue for the logical plausibility of this interpretation. However, other alternative interpretations of our results remain possible, and these are also discussed, along with potential future research ideas which might differentiate between competing explanations.