Behavioral analysis of visual discrimination of sex in female macaque monkeys

In this study, the performance of visually guided sex discrimination and sex preference tasks were investigated in female macaque monkeys to elucidate visual functions in sex discrimination. In the sex discrimination task, monkeys were able to discriminate the sex of a monkey shown in pictures on a computer display. During the discrimination task, some neurons in the orbitofrontal cortex responded specifically to pictures of either male or female monkeys. In the sex preference task, some monkeys watched video movies of either males or females significantly longer than female or male movies, respectively. This preference tendency was consistent with each individual. These results indicated that visual information alone was sufficient to discriminate sex and produce sex preference. The orbitofrontal cortex may be one of the sites responsible for sex discrimination.