Color discrimination by the cotton-top tamarin (Saguinus oedipus oedipus) and its relation to fruit coloration.

Old World monkeys and apes have been reported to differ from New World monkeys in their abilities to discriminate colors across the visible spectrum. Old World monkeys and apes (Macaca, Pan, Pongo) discriminate colors quite accurately, while some New World monkeys studied (Saimiri, Cebus) have shown lower sensitivity to and poorer discrimination of long wavelength light. This study examined the color discrimination ability of another New World primate, the cotton-top tamarin, Saguinus oedipus oedipus (family Callitrichidae). The tamarins were trained to discriminate a set of Munsell color chips, both within the same hue category and from the 2 hue categories on either side of the training hue. Results indicated that the cotton-top tamarin can make accurate discriminations across the visible spectrum. Human subjects were tested under similar conditions in order to compare their color discrimination abilities to those of the tamarins. The tamarins and human subjects had the most difficulty discriminating the same hues. The discrimination abilities of the monkeys were assessed in relation to the coloration of fruits eaten in a natural environment. A list of the species of fruits commonly eaten by various species of New World monkeys was compiled and the coloration of fruits at maturity was noted. It was found that most New World primate species eat fruits whose mature coloration ranges across most of the spectrum.