Determinants of infants' understanding of supporting relations: amount of contact versus position of the center of gravity.

This study investigated the developmental age at which infants recognize about supporting relations between objects and what information they use to judge whether a supported object will fall down or not. Four kinds of events were used. All events involved support in relation of two boxes, which differed in the amount of contact between objects and the amount of discrepancy between the supported object's position and its most balanced position. 115 infants (3 to 13 mo.) saw 4 events which differed on these two variables. Infants 10 months and older looked longer at the event in which the center of a supported box was just outside of the edge of a supporting box, that is, a support relation in which it was difficult to anticipate whether the box would fall down or not. Analysis suggested that infants' attention is not determined by only one simple stimulus variable but by more complicated variables (such as uncertainty of prediction).