Comparison of Categorical Color Perception in Two Estrildid Finches

Sensory systems are predicted to be adapted the perception of important stimuli, such as signals used in communication. Prior work has shown that female zebra finches perceive carotenoid-based orange-red coloration male beaks—a mate choice signal—categorically. Specifically, females exhibited an increased ability discriminate between colors from opposite sides a perceptual category boundary than equally different same side boundary. The Bengalese finch, estrildid finch related is black, brown, and white, lacking carotenoid coloration. To explore relationship categorical color signal use, we tested using continuum finches, also how both species discriminated among differing systematically hue brightness. Unlike found no evidence finches. Instead, combination chromatic distance (hue difference) Michelson contrast (difference brightness) strongly correlated with discrimination on all pairs pattern was finches: this strong correlation held when discriminating categories but not within category. These experiments suggest universal feature avian—or even finch—vision. Our findings provide further insights into mechanism underlying consistent hypothesis for perception.