Social competence is reduced in socially deprived rhesus monkeys (Macaca mulatta)

Rhesus monkeys deprived for some period from their mother have often served as a model for the effect of adverse rearing conditions on social competence in humans. Social competence is the capacity to react in a species-specific way to social interactions. The current study assesses whether early deprivation from peers also affects the rates of […]

Melatonin promotes sleep in three species of diurnal nonhuman primates

Nocturnal melatonin secretion is concurrent with consolidated sleep episodes in diurnal mammals and physiological melatonin levels can promote sleep onset in humans and in pigtail macaques. In order to further investigate the effects of melatonin treatment on sleep parameters in diurnal nonhuman primates, three macaque species have been studied: Macaca nemestrina, Macaca fascicularis, and Macaca […]

Mother–infant interactions in free-ranging rhesus macaques: Relationships between physiological and behavioral variables

Studies of mother–infant relationships in nonhuman primates have increasingly attempted to understand the neuroendocrine bases of interindividual variation in mothering styles and the mechanisms through which early exposure to variable mothering styles affects infant behavioral development. In this study of free-ranging rhesus macaques on Cayo Santiago, Puerto Rico, we aimed to: 1) compare lactating and […]

Effects of social deprivation on maternal behavior of rhesus monkeys

The primary differences between the design of this experiment and that of Seay, Alexander, and Harlow (1964) concerning the maternal behavior of motherless mothers (MMs) were extending of the observation period and balancing the groups for sex of the infants. As in the previous study, females separated at birth from their own mothers and deprived […]

Assessment of stress in non-human primates- application of the neutrophil activation test

A technique measuring leukocyte (neutrophil) activity was used to examine differences between stress levels in a breeding colony of rhesus macoques housed in either a traditional caging system or open-rooms. The leukocyte activation test measured the degree to which blood from the two treatment groups could launch a further neutrophil response (superoxide production) to an […]

The effect of spatial contiguity on discrimination learning by rhesus monkeys.

The role of spatial contiguity in learning was tested in a visual discrimination problem with monkeys, by varying the vertical spatial separation between the differential stimuli and the locus of response. An inverse relationship between spatial separation and performance efficiency was found

Recognizing Facial Cues: Individual Discrimination by Chimpanzees (Pan troglodytes) and Rhesus Monkeys (Macaca mulatta)

Faces are one of the most salient classes of stimuli involved in social communication. Three experiments compared face-recognition abilities in chimpanzees ( Pan troglodytes) and rhesus monkeys ( Macaca mulatta). In the face-matching task, the chimpanzees matched identical photographs of conspecifics’ faces on Trial 1, and the rhesus monkeys did the same after 4 generalization […]

Individual Characteristics: Weaving Psychological and Ethological Approaches

The chapter begins by outlining the development of the questionnaire for assessing individual characteristics of rhesus monkeys in the Madingley colony. The steps taken in preparing items, obtaining reliability and validity, and condensing items are presented, along with examples of how scores arising from principal component analyses can be put to use. In our own […]

A Fruit in Hand is Worth Many More in the Bush: Steep Spatial Discounting by Free-Ranging Rhesus Macaques (Macaca mulatta)

Decision making is one of the principal cognitive processes underlying goal-directed behaviour and thus there is justifiably strong interest in modeling it. However, many of these models have yet to be tested outside of the laboratory. At the same time, field work would benefit from the use of experimental methods developed in the laboratory to […]

Categorization of natural stimuli by monkeys (macaca mulatto)- effects of stimulus set size and modification of exemplars

The concept humans was studied in two experiments on rhesus monkeys, in each of which a two-choice simultaneous discrimination procedure was used. In Experiment 1, the choice was between scenes with humans and scenes without humans, with the slide set sizable enough that a large number of trials could be given without repeating any individual […]