Object distance as a determinant of visual fixation in early infancy.

Data from two experiments show that the duration of visual fixation of solid objects by infants aged 6 to 20 weeks varies as a function of object distance between 30 and 90 centimeters. There was no characteristic habituation of fixation of an object at 90 centimeters but there was a marked increase in fixation time when objects were advanced to 30 centimeters (experiment 1). A linear decline in fixation times occurred as the object distance increased from 30 to 90 centimeters with the real size and the angular size of the object held constant (experiment 2). No evidence for visual size constancy in young infants was obtained by this method.