Across the life-span, the performance in problem-solving tasks varies strongly, due to age-related variation in cognitive abilities as well as the motivation to engage in a task. Nonhuman primates provide an evolutionary perspective on human cognitive and motivational aging, as they lack an insight into their own limited lifetime, and aging trajectories are not affected by customs and societal norms. To test age-related variation in inhibitory control, cognitive flexibility, and persistence, we presented Barbary macaques (Macaca sylvanus), living at La Forêt des Singes in Rocamadour (France), with three problem-solving tasks. We conducted 297 trials with 143 subjects aged 2—30 years. We found no effect of age on success and latency to succeed in the inhibitory control task. In the cognitive flexibility task, 21 out of 99 monkeys were able to switch their strategy, but there was no evidence for an effect of age. Yet, the persistence in the motivation task as well as the overall likelihood to participate in any of the tasks declined with increasing age. These results suggest that motivation declines earlier than the cognitive abilities assessed in this study, corroborating the notion that non-human primates and humans show similar changes in motivation in old age.

Raw data and R code for statistical analysis