Maracas for Macaca? Evaluation of three potential enrichment objects in two species of zoo-housed macaques

Abstract 10.1002/1098-2361(2000)19:33.3.CO;2-N One group each of Barbary macaques and stump-tailed macaques, both zoo-housed, received hard replica fruits in three experimental conditions: as empty (“unresponsive”) objects, as maracas that rattled when manipulated (“simple responsive”), and as objects from which food items could be extracted (“foraging devices”). Both groups manipulated the replica fruits most when they functioned […]

Do rhesus monkeys recognize themselves in mirrors?

Abstract Self-recognition continues to attract attention because of the evidence of a striking difference between the great apes and humans, on the one hand, and all other primates; the former are capable of self-recognition, whereas no compelling evidence exists for prosimians, monkeys, or lesser apes. This is in spite of numerous attempts to facilitate mirror […]

Capuchins (Cebus apella) can solve a means-end problem

Three capuchin monkeys (Cebus apella) were tested on a 2-choice discrimination task designed to examine their knowledge of support, modeled after Hauser, Kralik, and Botto-Mahan’s (1999) experiments with tamarins. This task involved a choice between 2 pieces of cloth, including 1 with a food reward placed on its surface, and a second cloth with the […]

Beyond stimulus cues and reinforcement signals: A new approach to animal metacognition

Some metacognition paradigms for nonhuman animals encourage the alternative explanation that animals avoid difficult trials based only on reinforcement history and stimulus aversion. To explore this possibility, we placed humans and monkeys in successive uncertainty-monitoring tasks that were qualitatively different, eliminating many associative cues that might support transfer across tasks. In addition, task transfer occurred […]

Comparative behavior of primates. VII. Capacity of monkeys to solve patterned string tests.

31 monkeys, of several species, were required to pull in one of a group of strings arranged before them in various patterns, the correct string being baited with a piece of apple. The authors found that both simple and complicated patterns could be solved by Old and New World monkeys. Marked individual differences appeared. Comparison […]

Paired-comparisons scales for monkey rewards

The method of paired comparisons is applied to food incentives for monkeys, both for amounts and kinds of food. It was found that scale values for rewards (peanuts) was proportional to the logarithm of quantity for the range between ¼ peanut to 4 peanuts. Using 5 qualitatively different foods it was shown that reliable scale […]

Rhesus monkeys (Macaca mulatta) and capuchin monkeys (Cebus apella) remember future responses in a computerized task

Planning is an important aspect of many daily activities for humans. Planning involves forming a strategy in anticipation of a future need. However, evidence that nonhuman animals can plan for future situations is limited, particularly in relation to the many other kinds of cognitive capacities that they appear to share with humans. One critical aspect […]

Behavioural Responses to Photographs by Pictorially Naïve Baboons (Papio Anubis), Gorillas (Gorilla Gorilla) and Chimpanzees (Pan Troglodytes)

This study assessed how pictorially naive nonhuman primates understand pictures. Fifty-five baboons with no prior exposure to pictures were trained to grasp a slice of banana presented against a pebble in a two alternative forced choice task. Post-training testing involved three stimulus pairs: (1) real banana slice vs. its picture, (2) the banana picture vs. […]

Social subordination impairs hypothalamic–pituitary–adrenal function in female rhesus monkeys

Linear dominance hierarchies organize and maintain stability in female rhesus macaque (Macaca mulatta) social groups regardless of group size. As a consequence of their low social status, subordinate females suffer from an array of adverse outcomes including reproductive compromise, impaired immune function, and poor cardiovascular health. However, data that differentiate limbic–hypothalamic–pituitary–adrenal axis (LHPA) parameters between […]

Effects of trait anxiety on performance of socially housed monkeys in a learning test

Studies of individual cognitive capacities of socially housed monkeys may profit from a better understanding of the factors that influence individual performance in test procedures. Trait anxiety of subjects may be an essential factor affecting their performance in cognitive tests. Yet, in contrast to humans and rodents where this relation has been found, there is […]