Visual feature binding in early infancy.

How does the developing brain of the human infant solve the feature-binding problem when visual stimuli consisting of multiple colored objects are presented? A habituation--dishabituation procedure revealed that 1-month-old infants have the ability to discriminate changes in the conjunction of a familiar shape and color in two objects. However, this good earlier performance was followed by poorer performance at 2 months of age. The performance improved again at 3 months of age. Detailed analysis of the oculomotor behaviors revealed that the age of 2 months was a period of drastic transition when the tendency to stay with the fixated objects disappeared and repetitive saccades between the two objects emerged. Our findings suggest that the ability to perceive conjunctions of features is available to infants very early, that the perceptual/neural basis at 1 and at 3 months of age may be fundamentally different, and that feature integration by vigorous eye movements or selective attention may be the key functional difference between the age groups.