Transfer of odd-item search performance in a chimpanzee (Pan troglodytes)

An adult female chimpanzee (Pan troglodytes) who was trained only on odd-item search with a large number of items was tested for transfer of the odd-item search performance to new stimuli and to minimal items (1 target and 2 uniform distractors). The subject showed transfer to new target-distractor pairs when the number of items was large enough but showed no transfer to a minimal display even when the trained (old) target-distractor pair was presented. The results suggest that her performance on odd-item search was controlled mainly by perceptual cues such as pop-out of the target among the uniform distractors but not on relational cues such as the oddity rule.