Abstract
Recent studies have revealed asymmetries in color perception for blue vs. yellow: blue appears more achromatic, whilst yellow appears more saturated. These asymmetries may reflect a prior of the visual system to attribute blue to the lighting and yellow to the objects, because lighting from the sky and in shadows tends to be bluish. To examine when these asymmetries are acquired during development, we compared visual salience for blue/gray changes versus complementary yellow/gray changes with the same chromatic contrast, in infants aged 4-8 months. The colors were shown as patches or as object colors in two different experiments. In both cases, the color changes were presented side by side alternately with a 200 ms ISI. Looking time was measured to test for a spontaneous preference of infants for yellow/gray changes. The results showed that infants aged 6-8 months, but not 4-5 months, looked longer at yellow/gray changes in both color patches and objects images. This suggests that the infants perceived the yellow/gray changes as more salient and possibly as a change in surface rather than lighting color. We also confirmed that infants have similar detection sensitivities to blue and yellow, suggesting that the different preferences for blue/gray changes and yellow/gray changes stem from a higher-order appearance or inference about color rather than a developmental difference in peripheral processing. We used the identical paradigm to also examine whether adults perceived lower salience in the color changes along a bluish axis than along a yellowish or reddish or greenish axis. The results showed similar tendencies to the infants aged 6-8 months: adults reported lower saliences in color changes along the bluish axis than other directions. Our results establish an early developmental trajectory for blue-yellow asymmetries in infants, which may depend on experience with the natural lighting asymmetries arising from sun and sky.