Infant color vision: the effect of test field size on Rayleigh discriminations

The capacity of 1- and 3-month-old infants to discriminate 589 nm and 650 nm test fields from a 589 nm surround was tested using the forced-choice preferential looking (FPL) technique. The size of the test field ranged from 1 to 8 degrees. Test field size strongly influenced the infants' performance. One-month-olds discriminated 8 and 4 degrees (but not 2 degrees) 650 nm fields from the 589 nm surround; 3-month-olds discriminated 4 and 2 degrees (but not 1 degree) 650 nm fields from the 589 nm surround. The dependence of performance on field size suggests that infants' discrimination failures with small fields are due to immaturities of spatial processing or postreceptoral chromatic mechanisms, rather than to any absence or anomaly of receptor types. In addition, adult subjects rated the hue, brightness, and salience of the test stimuli at 0, 26, 52, and 78 degrees eccentricity. The analogy often made between infant vision and adult peripheral vision is discussed in relation to these data.