Rhesus monkeys use geometric and nongeometric information during a reorientation task.

Abstract

Rhesus monkeys (Macaca mulata) were subjected to a place finding task in a rectangular room perfectly homogeneous and without distinctive featural information.Results of Experiment 1 show that monkeys rely on the large-scale geometry of the room to retrieve a food reward.Experiments 2 and 3 indicate that subjects use also nongeometric information (colored wall) to reorient.Data of Experiments 4 and 5 suggest that monkeys do not use small angular cues but that they are sensitive to the size of the cues (Experiments 6, 7, and 8).Our findings strengthen the idea that a mechanism based on the geometry of the environment is at work in several mammalian species.In addition, the present data offer new perspectives on spatial cognition in animals that are phylogenetically close to humans.Specifically, the joint use of both geometric and landmark-based cues by rhesus monkeys tends to demonstrate that spatial processing became more flexible with evolution.Most of the studies of spatial representations in animals rely on the concept of cognitive map (Tolman, 1948), involving a kind of "bird's eye view" of the environment, which makes it possible to move efficiently in space between places charted on a map.Spatial behaviors of several species have been studied in such a perspective, with the aim to demonstrate that animals do have spatial representations endowed with adaptive properties.Indeed, many animal species appear to be able to construct and use cognitive maps to orient, ranging from fishes (Lopez, Broglio, Rodriguez, Thinus-Blacc, & Salas, 1999) to monkeys (Joubert & Vauclair, 1986;Menzel, 1973Menzel, , 1978)), though the most extensive studies have been conducted in rats at both the behavioral and brain level (see Thinus-Blacc, 1996, for review).Many environmental features are likely to serve as constitutive elements of spatial representations, and understanding their nature is relevant for a more extensive analysis of the spatial mapping