Much of the research on object individuation in infancy has used a task in which two different objects emerge in alternation from behind a large screen, which is then removed to reveal either one or two objects. In their seminal work, Xu and Carey (1996) found that it is typically not until the end of the first year that infants detect a violation…

Until recently, it was generally assumed that the ability to attribute false beliefs did not emerge until about 4 years of age. However, recent reports using spontaneous- as opposed to elicited-response tasks have suggested that this ability may be present much earlier. To date, researchers have employed two kinds of spontaneous-response…

Reports that infants in the second year of life can attribute false beliefs to others have all used a "search" paradigm in which an agent with a false belief about an object's location searches for the object. The present research asked whether 18-month-olds would still demonstrate false-belief understanding when tested with a novel "non-search"…

The present research examined whether 5- to 6.5-month-old infants would hold different expectations about various physical events involving a box after receiving evidence that it was either inert or self-propelled. Infants were surprised if the inert but not the self-propelled box: reversed direction spontaneously (Experiment 1); remained…

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…

Prior research suggests that children younger than age 3 or 4 do not understand that an agent may be deceived by an object's misleading appearance. The authors asked whether 14.5-month-olds would give evidence in a violation-of-expectation task that they understand that agents may form false perceptions. Infants first watched events in which an…

As they observe or produce events, infants identify variables that help them predict outcomes in each category of events. How do infants identify a new variable? An explanation-based learning (EBL) account suggests three essential steps: (1) observing contrastive outcomes relevant to the variable; (2) discovering the conditions associated with…

Violation-of-expectation (VOE) tasks have revealed substantial developments in young infants' knowledge about support events: by 5.5 months, infants expect an object to fall when released against but not on a surface; and by 6.5 months, infants expect an object to fall when released with 15% but not 100% of its bottom on a surface. Here we…

Do 18-month-olds understand that an agent's false belief can be corrected by an appropriate, though not an inappropriate, communication? In Experiment 1, infants watched a series of events involving two agents, a ball, and two containers: a box and a cup. To start, agent 1 played with the ball and then hid it in the box, while agent 2 looked on.…

The present research examined whether 12.5-month-old infants take into account what objects an agent knows to be present in a scene when interpreting the agent's actions. In two experiments, the infants watched a female human agent repeatedly reach for and grasp object-A as opposed to object-B on an apparatus floor. Object-B was either (1) visible…

Eight experiments involving 134 infants aged 7.5 to 11.5 months show that even the youngest give evidence that they use featural information to individuate objects in an occlusion event. When tested with an event-mapping task, even 9.5-month olds give evidence that they can use featural information to interpret an occlusion event as long as the…

This study examined two alternative interpretations of violation-of-expectation findings that young infants can represent hidden objects. Findings indicated that 5-month-olds succeeded in reasoning about the interaction of a visible and a hidden object even though the 2 objects were never simultaneously visible and a 3- or 4-minute delay preceded…

Five experiments demonstrated that 6.5-month-olds perseverated in a violation-of-expectation task to examine reasoning about width information in containment events. After watching a familiarization event in which a ball was lowered into a wide container, infants failed to detect the violation when the same ball was lowered into a container half…

Prior research suggests that infants attend to a variable in an event category when they have identified it as relevant for predicting outcomes in the category, and that the age at which infants identify a variable depends largely on the age at which they are exposed to appropriate observations. Thus, depending on age of exposure, infants may…

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…