DEVELOPMENT OF RESPONSIVENESS TO NOVEL OBJECTS IN THE TITI MONKEY, CALLICEBUS MOLOCH

Adult titi monkeys react to novelty more strongly and cautiously than other New World primates. Developmental changes in responsiveness were assessed by presenting complex novel objects to family groups consist ing of 11 male-female pairs and their admit (31-33 months), subadult ( 20-23 months), and juvenile offspring (10-16 months). Food and a simpl e block were included as control conditions. Differences in attraction to novel objects were inversely related to age. Juveniles approached more objects, more quickly, and spent more time near them than older s ubjects. Parents, the least responsive age-group, seemed more indiffer ent than cautious. Age-effects were smaller with the block, and neglig ible with food. Even in the most responsive age-group, investigatory b ehavior appeared subdued as compared to other primate species.