Emergence of the ability to discriminate a blue from gray at one month of age

Two different methods which minimize achromatic cues were used to test the ability of 1-month-olds to discriminate gray from broadband blue (lambda peak = 475-480 nm). Unlike the newborns we tested previously, 1-month-olds demonstrated the discrimination with both methods. In Experiment 1 they showed preferences for each of four blue-and-gray checkerboards over gray squares of the same mean luminance, even though the luminance of the gray …