Psychology, Department of


Date of this Version


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Stevens, J.R., Marewski, J.N., Schooler, L.J., & Gilby, I.C. (2016). Reflections of the social environment in chimpanzee memory: Applying rational analysis beyond humans. Royal Society Open Science, 3, 160293.
DOI: 10.1098/rsos.160293


Data and R code available at

Copyright (c) 2016 Jeffrey R. Stevens, Julian N. Marewski, Lael J. Schooler, and Ian C. Gilby.
Published by the Royal Society under the terms of the Creative Commons Attribution License 4.0.


In cognitive science, the rational analysis framework allows modelling of how physical and social environments impose information-processing demands onto cognitive systems. In humans, for example, past social contact among individuals predicts their future contact with linear and power functions. These features of the human environment constrain the optimal way to remember information and probably shape how memory records are retained and retrieved. We offer a primer on how biologists can apply rational analysis to study animal behaviour. Using chimpanzees (Pan troglodytes) as a case study, we modelled 19 years of observational data on their social contact patterns. Much like humans, the frequency of past encounters in chimpanzees linearly predicted future encounters, and the recency of past encounters predicted future encounters with a power function. Consistent with the rational analyses carried out for human memory, these findings suggest that chimpanzee memory performance should reflect those environmental regularities. In re-analysing existing chimpanzee memory data, we found that chimpanzee memory patterns mirrored their social contact patterns. Our findings hint that human and chimpanzee memory systems may have evolved to solve similar information-processing problems. Overall, rational analysis offers novel theoretical and methodological avenues for the comparative study of cognition.