MONKEYS (MACACA-MULATTA) LEARN CATEGORY MATCHING IN A NONIDENTICAL SAME-DIFFERENT TASK

Same-different judgments of familiar objects and animals were investig ated in rhesus monkeys (Macaca mulatta) in a task based on category ma tches rather than identity matches. Eighteen categories of familiar an imals and objects were each composed of 12 color slides and were prese nted as pairs of slides. Ss indicated ''same'' or ''different'' on a r esponse lever for reinforcement. On Same trials, 2 different views of the same object were presented, typically with differences in perspect ive, lighting, and background. On Different trials, 2 pictures of diff erent objects were presented. Ss acquired the category discriminations and transferred their response judgments accurately to novel pictures from the categories. Transfer was better to objects with which the mo nkeys had actually interacted rather than those with which they did no t interact.