Comparative Physiological Study of the Processes of Recognition of Different Numbers of Two- and Three-Dimensional Objects and Their Identification in Lower and Higher Monkeys

Abstract

The capability of monkeys for comparison and identification of plane images and three-dimensional objects has been studied using tasks of the “sample choice” type. The study was performed on three species of monkeys with different level of phylogenic development: rhesus macaques Macaca mulatta, brown capuchins Cebus apella, and chimpanzee Pan troglodites. It has been established that representatives of the studied species are able to differentiate two-dimensional images of berries and corresponding three-dimensional models in various quantitative ratios from 1 to 5 and to choose identical signs of stimuli in solving problems of the “sample choice” type. These circumstances argue in favor of the existence of quantitative notions in primates and their capability of counting in the limits from 1 to 5. Rhesus macaques had difficulties in solving complicated combinatory tasks. The obtained facts indicate a sufficiently high level of the pre-verbal cognition in primates.