Abstract
Abstract: :
Purpose: To explore the visual capabilities of animals with different photopigments, we devised a method that allows humans to behave as surrogates for animals with particular cone spectral sensitivities. Methods: A calibrated computer monitor was used to create patterns of excitation in human photoreceptors equivalent to the patterns of excitation in photoreceptors of animals viewing ecologically relevant objects. In one case, we used human surrogates to examine the abilities of New World tamarin monkeys. Polymorphism in tamarin photopigment genes produces several color vision phenotypes. Humans were asked to discriminate between colors simulating ripe and non–ripe fruit as they would appear to human observers with tamarin photopigments. We compared discriminability of fruit across different simulated phenotypes. In the second case, we used humas as surrogates for stickleback fish. Many studies have demonstrated correlations between behavioral responses of stickleback to male fish and human assessments of the colors of those fish. We explored the extent to which color assessments depend on photopigment phenotype by having human subjects rank colors simulated to reproduce the appearance of those colors to a normal human and to a human with stickleback photopigments. Results: The accuracy with which human subjects could discriminate simulated fruit colors depended upon which tamarin pigment set was substituted for the subjects' own pigments. On the other hand, a subject's rankings of simulated fish colors was substantially the same whether the colors were viewed through human pigments or through stickleback pigments. Conclusions: Our general methods may be used economically to explore various questions about perceptual capabilities of non–human animals. In two applications, we (1) amassed data suggesting that differences in the frequencies of tamarin photopigment alleles may be a result of selection for particular color vision phenotypes, and (2) showed that differences in the color vision of humans and stickleback fish may not be significant in the context of human and fish assessments of courtship display colors.
Keywords: color vision • color pigments and opsins • photoreceptors: visual performance