A dynamic account of the A-not-B error in capuchin monkeys (Cebus apella)
Rosengart, Carrie Robin
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Piaget (1954) found that between 8 to 10 months of age children retrieved an object from a hiding location (A), and were able to do this on repeated trials. However, if the object were switched to a new hiding lo25cation (B) the child would perseverate and search the original A hiding location. This error was more likely to be observed as the delay between hiding and the opportunity for searching increases. Memory mechanisms are not sufficient to explain all findings (i.e., children make errors even when objects are placed under translucent cups). The purpose of this research was to explore the circumstances that lead capuchin monkeys (Cebus apella) to make the A-not-B error. According to the dynamic systems perspective the A-not-B error is due to the visual, attentional and motor process involved in searching for the object as well as the short-term memory for where the object was last seen and long-term memory about past searches rather than a lack of object permanence (knowledge that objects continue to exist when they are out of sight). This model was tested in two experiments with eight pair-housed monkeys. In both experiments, the delay between hiding a food reward and opportunity for retrieval was manipulated. Experiment 1 used discrete hiding locations and obvious spatial cues, and Experiment 2 used continuous hiding locations and few spatial cues. Each monkey was tested with four different delay conditions (0, 10, 30 and 120 seconds) for both A and B trials. Regardless of the amount of spatial cues, the monkeys were more accurate on A trials as compared to B trials. The two experiments were also comparable in the way increased delay periods caused decreases in search accuracy. On B trials in Experiment 2 the searches were biased towards the A location. It appears that motor activity associated with searching at the A location contributes to the A-not-B error. This study supports the dynamic systems account for the A-not-B error, indicating the perseverative searching is a more general phenomenon than had previously been suggested.