Brown Lemurs (Eulemur fulvus) Can Master the Qualitative Version of the Reverse-Reward Contingency

Behavioral flexibility that requires behavioral inhibition has important fitness consequences. One task commonly used to assess behavioral inhibition is the reverse-reward task in which the subject is rewarded by the non selected items. Lemurs were tested for their ability to solve the qualitative version of the reverse-reward task with the choice between identical quantities of different food items instead of different quantities of the same food. Two of four subjects mastered the task without a correction procedure and were able to generalize the acquired rule to novel combinations of food. One of the two subjects competent on the quality version of the task could transfer this ability to different quantities of the same food. Our results are compared to lemurs' performances when tested under the quantitative version in a previous study and those of capuchin monkeys tested under a similar paradigm. The whole results suggest that the qualitative version of the reverse-reward task may be easier to master than its quantitative counterpart and that lemurs perform better than capuchin monkeys as they were able to later transfer the learning rule to the quantitative version of the task.