Object representation guides infants' reaching in the dark.

Infants were presented with two sounding objects of different sizes in light and dark, in which sound cued the object's identity. Reaching behavior was assessed to determine if object size influenced preparation for grasping the object. In both light and dark, infants aligned their hands when contacting the large object compared with the small object, which resulted in a reach with both hands extended for the large object and reach with one hand more extended for the small object. Infants contacted the large object more frequently on the bottom and sides rather than the top, where the sound source was located. Reaching in the dark by 6 1/2-month-olds is not merely directed toward a sound source but rather shows preparation in relation to the object's size. These findings were interpreted as evidence that mental representation of previously seen objects can guide subsequent motor action by 6 1/2-month-old infants.