Perseveration on a Reversal-learning Task Correlates with Rates of Self-directed Behavior in Nonhuman Primates
In humans and several nonhuman animals, repetitive behavior is associated with deficits on executive function tasks involving response inhibition. We tested for this relationship in nonhuman primates by correlating rates of normative behavior to performance on a reversal-learning task in which animals were required to inhibit a previously learned rule. We focused on rates of self-directed behavior (scratch, autogroom, self touch and manipulation) because these responses are known indicators of arousal or anxiety in primates, however, we also examined rates of other categories of behavior (e.g., locomotion). Behavior rates were obtained from 14 animals representing three nonhuman primate species (Macaca silenus, Saimiri sciureus, Cebus apella) living in separate social groups. The same animals were tested on a reversal-learning task in which they were presented with a black and a grey square on a touch screen and were trained to touch the black square. Once animals learned to select the black square, reward contingencies were reversed and animals were rewarded for selecting the grey square. Performance on the reversal-learning task was positively correlated to self-directed behavior in that animals that exhibited higher rates of self-directed behavior required more trials to achieve reversal. Reversal learning was not correlated to rates of any other category of behavior. Results indicate that rates of behavior associated with anxiety and arousal provide an indicator of executive function in nonhuman primates. The relationship suggests continuity between nonhuman primates and humans in the link between executive functioning and repetitive behavior.