Visual acuity in infants--the effect of variations in stimulus luminance within the photopic range

The forced-choice preferential looking technique was used to measure 2-month-old infants' visual acuity for black-and-white, square-wave gratings at six luminance values between -1.0 and 3.0 log cd/m2. The results indicated that the infants' acuity was relatively unaffected by variations in luminance above 1 log cd/m2, but was reduced by approximately 1 octave at a luminance of -0.8 log cd/m2. These results are in agreement with the results of adults tested in the same apparatus and with previously published data from adult subjects. Our results suggest that for infants, as for adults, variations in room illumination above 1.0 log cd/m2 have little effect on visual acuity.