Page 45 - Demo

Sexually selective cognition in primates432use facial symmetry to judge the quality of competitors. Second, Lonsdorf et al. (2019) investigated whether capuchin monkeys were biased towards same-sex or opposite-sex conspecifics. They found that females looked longer at same-sex stimuli, whereas no clear bias was found in males. Altogether, preferential looking tasks have been successfully applied to study mostly macaque species, even though a few studies have extended this method to other species.In addition to preferential looking tasks, some studies have used different test paradigms to investigate preferences for secondary sexual characteristics. Deaner et al. (2005) developed a pay-per-view paradigm in which rhesus macaques could give up a certain amount of their reward to look at pictures depicting different conspecifics. They found that individuals were willing to give up rewards to look at high-status faces and the perinea of conspecifics. Watson et al. (2012) adapted the paradigm into a free-ranging version. On a touchscreen, female rhesus macaques could choose between two coloured dots, one of which they had learned to associate with an empty screen and one with a specific image category during forced-choice trials at the start of the session. Irrespective of their choice, individuals received a reward at the end of each trial. By changing the image category between sessions, the authors identified the image categories that were most preferred over seeing an empty screen. Based on their choices, female macaques seemed to prefer pictures of perinea and high-status faces, confirming the results of Deaner et al. (2005). Thus, it seems that rhesus macaques choose to look at stimuli that contain traits indicative of good mate quality when they are “asked” what they want to see.In short, studies of sexually selective cognition in primates have mostly focused on attention and choice tasks. Furthermore, the range of species that have been tested is very narrow. Therefore, future studies should not only employ a wider range of paradigms encompassing different cognitive processes but also apply them to a wider range of species.Opportunities for sexually selective cognition research in primatesAs shown in this review, many different paradigms have been used to examine sexually selective cognition in humans, but relatively few have been employed in primates, even though some would be suitable for this purpose. Therefore, we suggest specific methods that can be employed in future primate research. Many Tom Roth.indd 43 08-01-2024 10:41