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When facing uncertainty, humans often build mental models of alternative outcomes. Considering diverging scenarios allows agents to respond adaptively to different actual worlds by developing contingency plans (covering one's bases). In a pre-registered experiment, we tested whether chimpanzees (Pan troglodytes) prepare for two mutually exclusive possibilities. Chimpanzees could access two pieces of food, but only if they successfully protected them from a human competitor. In one condition, chimpanzees could be certain about which piece of food the human experimenter would attempt to steal. In a second condition, either one of the food rewards was a potential target of the competitor. We found that chimpanzees were significantly more likely to protect both pieces of food in the second relative to the first condition, raising the possibility that chimpanzees represent and prepare effectively for different possible worlds. Postprint

When facing uncertainty, humans often build mental models of alternative outcomes. Considering diverging scenarios allows agents to respond adaptively to different actual worlds by developing contingency plans (covering one's bases). In a pre-registered experiment, we tested whether chimpanzees (Pan troglodytes) prepare for two mutually exclusive possibilities. Chimpanzees could access two pieces of food, but only if they successfully protected them from a human competitor. In one condition, chimpanzees could be certain about which piece of food the human experimenter would attempt to steal. In a second condition, either one of the food rewards was a potential target of the competitor. We found that chimpanzees were significantly more likely to protect both pieces of food in the second relative to the first condition, raising the possibility that chimpanzees represent and prepare effectively for different possible worlds.

Description of the power analysis for Exp. 3 and supplementary figures and tables for Exp. 1-3.

Experiment 1: Description of the 3D tracking setup, the pre-processing of the 3D data, and of the assumption checks, and detailed results of all models. Experiment 2: Description of the setup and the warm-up procedure, additional analyses concerning potential effects of control predictor variables (e.g., order effects), and detailed results of all models.

Additional materials; Raw data and analyses

The field of primate cognition studies how primates, including humans, perceive, process, store, retrieve, and use information to guide decision making and other behavior. Much of this research is motivated by a desire to understand how these abilities evolved. Large and diverse samples from a wide range of species are vital to achieving this goal. In reality, however, primate cognition research suffers from small sample sizes and is often limited to a handful of species, which constrains the evolutionary inferences we can draw. We conducted a systematic review of primate cognition research published between 2014 and 2019 to quantify the extent of this problem. Across 574 studies, the median sample size was 7 individuals. Less than 15% of primate species were studied at all, and only 19% of studies included more than one species. Further, the species that were studied varied widely in how much research attention they received, partly because a small number of test sites contributed most of the studies. These results suggest that the generalizability of primate cognition studies may be severely limited. Publication bias, questionable research practices, and a lack of replication attempts may exacerbate these problems. We describe the ManyPrimates project as one approach to overcoming some of these issues by establishing an infrastructure for large-scale collaboration in primate cognition research. Building on similar initiatives in other areas of psychology, this approach has already yielded one of the largest and most diverse primate samples to date and enables us to ask many research questions that can only be addressed through collaboration

Supplementary text file including additional details regarding the methods and analyses, additional results, and result tables of all GLMMs.