Smart Ungulates: What Sheep and Goats' Performances in a Reversed-Reward Contingency Task Tell Us About the Evolution of Cognitive Flexibility.

Cognitive flexibility and inhibitory control are core executive functions that enable animals to adapt their behaviour to variable environments. Although these abilities are extensively studied in primates, and despite a growing interest in ungulate cognition, research specifically targeting executive functions in ungulates remains limited. In this study, we compare the performance of domestic goats (Capra hircus) and sheep (Ovis aries) in a reversed-reward contingency (RRC) task. This task is traditionally used to test inhibitory control (the ability to resist a prepotent response), but it should also involve cognitive flexibility (the ability to adapt to changed contingencies). Overall, goats performed better than sheep. Two young goats met the success criterion spontaneously, and two more succeeded following corrective procedures. No sheep exceeded chance-level performance. Only younger goats solved the task, confirming that cognitive flexibility is indeed a core process in this task for ungulates. The differences between sheep and goats reflect subtle differences in their behavioural flexibility both in the social and ecological domains. These results extend comparative cognition research beyond primates, highlighting ungulates as promising models for studying the evolution of executive functions.