Object Permanence in 3 ½- and 4 ½-Month-Old Infants The article Object Permanence in 3 ½- and 4 ½-Month-Old Infants by Renee Baillargeon is based on the developmental psychology topic of object permanence. Object permanence is the ability of an individual to believe that an object cannot exist at two separate points in time without having existed during the interval between them. In psychology’s early stages, Piaget held that infants do not share this belief with adults until about nine months of age after observing infants’ reactions to hidden objects. Although Piaget’s observations have been confirmed by numerous researchers, many also have questioned his interpretations. Some believe a greater amount of the infants’ behavior in his tests was a result of lacking coordination skills and not necessarily a lack of the understanding of object permanence. The interpretation of many suggests that young infants might show evidence of object permanence if tests were administered that did not require coordinated actions, and Baillargeon sought to do just that. A test was designed that would determine if infants were surprised when a visible object appeared to move through the space occupied by another solid object, consisting of a screen that could rotate 180 degree in a fashion similar to a drawbridge and a wooden box that could be lowered and raised. The subjects of the study consisted of twenty-four full-term infants ranging in age from four months, two days, to five months, two days, with half of the infants being assigned to the experimental condition and the other half to the control condition. The experimental condition events consisted of an impossible test event, a possible test event, and a habituation event. In the impossible test event, the screen would lay flat toward the infant with the box visible and in the path of the screen; the screen would