Predictors of participation in a choice and sequence task using multiple touchscreens in wild chacma baboons

Participation in cognitive tests by individuals can vary because of neophobia, motivation, environment and social factors. Inconsistent participation in cognitive experiments can lead to misleading conclusions. To better understand what might drive such inconsistencies, we explored individual patterns of participation and how these related to individual traits in a wild population of chacma baboons, Papio ursinus , using the first multi-touchscreen experiment conducted with primates. We tested 142 individuals of varying age, sex and rank across two study groups using two touchscreen tasks of differing complexity. Participation in this study was at a similar level to that reported in captive studies. Using a mixed-model approach, we found that participation varied between individuals, and that young individuals were the most likely to participate at least once. However, older individuals participated for the longest periods. No sex difference was found in the likelihood of participation, but males participated for longer during sessions than females. We found that rank had no impact on participation, probably because the multi-touchscreen set-up allowed low-ranking individuals to participate elsewhere if displaced by high-ranking individuals. A preference for participating in the easier task was consistent across age, sex and rank. These results suggest that predictors of individual participation can be identified, meaning that experimental designs should accommodate potentially species- or group-specific factors that influence participation or otherwise statistically control for potential biases.