The inhibition of automatic saccades in early infancy.

Adult patients with damage centered around the frontal eye fields are severely impaired in the ability to suppress unwanted automatic saccades and in the ability to make volitional eye movements. Over the first few weeks of life most saccades generated by infants appear to be automatic, and are triggered in response to exogenous factors. In the first experiment, the ability of 4-month-old infants to inhibit automatic saccades was studied by exposing them to a series of trials in which a peripheral cue stimulus predicted the location (opposite) in which a colorful, dynamic target stimulus appeared. The results indicate that 4-month-old infants are able to learn to inhibit automatic saccades to a peripheral stimulus, implying maturation of the frontal eye fields by this age. The results of Experiment 2, in which there was no contingent relationship between the cue and target, indicated that the decline in orienting to the cue observed in the first experiment was not due to differential habituation to the less-complex stimulus.