Color preference and manual laterality in the emperor tamarin (Saguinus imperator)

The current research focuses on color preference between red and green stimuli and manual laterality in the emperor tamarin (Saguinus imperator). Trichromacy in primates has been related to a foraging advantage allowing frugivore primates to distinguish ripe from unripe fruits as well to socio-sexual communication, as trichromats would be advantaged in recognizing social and sexual signals. As warm colors can affect the emotive state of the subjects, leading to the activation of one hemisphere over the other (e.g., right hemisphere), this could lead to behavioral lateralization. Thus, studying of hand preference may be relevant when testing color preference. Nine adult zoo emperor tamarins were involved and the study aimed to investigate the preference between red, green, and white cones as well as manual laterality. Tamarins were provided with pairs of red-green, red-white, and green-white combinations of cones. Ten 30-min sessions per combination were carried out and data on the interaction with one of the two cones of each apparatus were collected to assess subjects' color preference. We also recorded the hand used by each subject during the interaction with cones of different colors and the position of the apparatus in respect to the tamarin. We found no preferences for colored versus white cones. Similarly, we reported no group-level preferences within different color combinations, whereas individual-level preferences were found when considering all choices. Finally, we found that red cones elicited a left-hand preference, suggesting a right-hemisphere involvement in the presence of red cones. Although we do not have genetic data on trichromat and dichromat females, the tendency to use the left hand when interacting with red stimuli provides further evidence that warm colors can influence the emotive state of the perceiver, affecting their manual lateralization.