Stimulus control and the growth of the infant’s effective visual field*

The size of the infant’s effective visual field was studied weekly in infants starting at 2 weeks of age until they were 10 weeks old, The field was initially quite small, 15 deg to either side of their line of regard. Over the 2-month period of the study, it more than doubled for stimulus conditions in which the peripheral event was in motion and the fixation object static, and it remained approximately the same size when motion was present in the fixation event and the peripheral object was static. As with adults, the infant’s effective visual field is directly related to the stimuli available.