Schematic of reward devaluation task and reversal learning tasks. A, All monkeys were trained on an OD task with 40 different object pairs in which one object was always rewarded while the other was never associated with a food reward. Twenty of the pairs were rewarded with food 1 (carrots in this example) and the other 20 pairs were rewarded with food 2 (pears in this example). The order of object pair presentation to the monkey and the food used to reward the correct response for each pair were consistent across all testing sessions. Monkeys were trained to a criterion performance of 90% correct over 5 consecutive days. After this was achieved, the monkey participated in four critical test sessions that were used to evaluate reward devaluation performance. B, C, For the four critical test sessions, only the rewarded objects from the original OD task were used, and the monkey performed 20 trials in which a food 1 object was paired with a food 2 object (left panels). During the Baseline Test 1 session on Day 1 (B; left), the monkey received no food before testing. On Day 2 the next day, testing was preceded by a selective satiation procedure for food 1 (carrots in this case; right panel). The 20-pair OD test session began within 10 min of the monkey completing the satiation procedure (B; right). Two days later, the animal performed the second baseline test (C; left). The day following the second baseline test, the monkey participated in another selective satiation procedure with food 2 and was again tested with food 1 and 2 objects within 10 min of completing satiation (C; right). D, Reversal learning testing began with the monkeys relearning the 40 object pairs from the first OD task to a criterion of 90% correct over 5 consecutive days. E, Once criterion performance was achieved, the rewarded object was reversed and a correct response corresponded to the animal selecting the previously unrewarded object. Testing continued until the monkey attained a performance of 90% correct for 5 consecutive days.