Individual differences in task participation in wild chacma baboons

Despite the controlled testing conditions that are typical of captive environments, many evaluations of animal cognition fail to ensure that all tested individuals participate. This is even more evident under wild conditions, as animals are not restricted in their movement or social interactions and have other activities available. In this study, we aimed to understand variation in cognitive task participation in wild chacma baboons, Papio ursinus. We quantified individual differences in the latency and likelihood to approach and explore two types of stimuli for two cognitive tests: a set of coloured paper bags (in an associative learning test) and a blue cardboard square (in a second-order conditioning test). We evaluated whether participation in each task was predicted by individuals' phenotypic traits/states, as well as by two additional aspects of their behaviour: (1) the availability of competing activities at the time of testing and (2) their propensity to exploit social information. We found consistent results for both types of stimuli regarding the effect of age: juveniles were more likely to contact the stimuli and explore them for longer. Similarly, for both tasks, individuals involved in an activity at the time of testing were less likely to contact the stimuli and had a lower exploration time. Finally, juveniles and females with a high propensity to use social information (i.e. scrounge) were more likely, and had shorter latencies, to contact the paper bags. Our findings not only highlight the potential bias cognitive studies conducted in the wild can have, but also some of the individual attributes and external factors that determine task participation. (c) 2020 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.