The differentiation of activity in infants' exploration of objects.

If an activity during manipulative play is exploratory, it should, in contrast to other activity, be used differentially for objects that vary in novelty. In a study of 5-month-olds, different definitions of exploratory mouthing were tested, and results suggested that mouthing followed immediately by a look fulfilled some criteria for an exploratory activity. In the next study of 5- to 11-month-olds, mouthing with looks after and examining, a measure of visual-manipulative inspection, met the criteria for exploratory activity; other kinds of mouthing and visual-manipulatory activity did not. Exploratory mouthing decreased with age and examining increased. The exploratory function of mouthing apparently was not due to concurrent manual activity providing haptic information. The conclusion is that some activities are exploratory and information-gathering and other activities are nonexploratory and serve other functions.