Young infants view physically possible support events as unexpected: New evidence for rule learning.

It has been suggested that one of the mechanisms by which infants acquire their physical knowledge is rule learning: Infants generate rules about the likely outcomes of events and revise these rules when confronted with discrepant outcomes. This approach predicts that when infants' rules are only partially correct, they will view as unexpected events that are physically possible and even ordinary but happen to contradict their faulty rules. Here we provide evidence for this prediction in young infants' responses to support events. According to prior findings, by 6.5months of age, most infants expect an object to be stable if released with half or more of its bottom surface on a support; by 8months, most infants have refined this rule and realize that an object can be stable with less support as long as the middle of the object's bottom surface is supported. In line with these findings, 7.5- but not 8.5-month-olds viewed as unexpected a possible event in which a wide box remained stable when released with only the middle third of its bottom surface resting on a narrow platform. These results provide new evidence that young infants, like older children and adults, generate and revise rules to make sense of physical events.