Recent research has shown that infants as young as 13 months can attribute false beliefs to agents, suggesting that the psychological-reasoning subsystem necessary for attributing reality-incongruent informational states (Subsystem-2, SS2) is operational in infancy. The present research asked whether 18-month-olds' false-belief reasoning extends…

Examined whether 6.5- and 5.5-month-old infants believe, like 11-month-old infants, that a moving object's size affects how far a stationary object is displaced in a collision. After a habituation event, tests indicated that the 6.5-month-old infants and 5.5-month-old female infants believed the size of the moving object affected the collision…

Three experiments test object permanenece in 3 1/2- and 4 1/2-month-old infants, and use an impossible-possible-habituation event format. The 4 1/2-month-olds, and the 3 1/2-month-olds who were fast habituators, look reliably longer at the impossible than at the possible event. Results seriously question Piaget's (1954) claims regarding the age at…

Examined infants' use of configural and physical knowledge in segregating three-dimensional adjacent displays. Found that infants do use configural knowledge: they expect similar parts to belong to same unit and dissimilar parts to belong to distinct units. Also found that physical knowledge, such as impenetrability and support, influences their…

Four experiments examined very young infants' expectations about containment events. Found that 2- to 3.5-month-olds recognized that objects could be lowered inside a container with an open but not a closed top. Three-and-a-half-month-olds realized that objects could not pass through the container's back wall and should have moved with it to a new…

Observed the reactions of 3.5-month-old infants looking at a carrot that should have but did not appear in a window after passing behind a screen. The results of this and several similar experiments indicated that 3.5-month-old infants are able to represent and reason about hidden objects. (BC)