Perceptual Development: Visual Object Permanence and Identity

Object Permanence

Early developmental psychologists, like Jean Piaget, believed that infants lacked object permanence until the end of the first year. Most of these studies relied on search methods, and infants' failure to search for hidden objects was believed to be indicative of their lack of knowledge that objects continue to exist when out of view. The rationale was that if infants knew that an object continued to exist when placed under a cover or a blanket, they would search for it. However, with the development of more sensitive research methods, including looking time, reaching in the dark, and simplified search tasks, there is now converging evidence from different laboratories using many different methods indicating that infants as young as 2.5 months possess object permanence, even though infants fail to search for hidden objects until about 8 months. Evidence that infants represent the existence of hidden objects has shifted the focus of research away from the question of whether infants possess object permanence to questions about the nature and content of infants' object representations. Current research suggests that infants possess some basic (or core) information about objects, but that this knowledge changes appreciably with time and experience. For example, even very young infants recognize that objects maintain their numerical identity across space and time, but there are age-related changes in the kind of information (e.g., the spatiotemporal or featural properties of the objects) that infants use to track objects.

Object Identity

Object identity was previously defined as the ability to determine whether two perceptual instances involve the same object or two different objects. However, object identity can be conceptualized as two distinct processes. One process, object individuation, is that of determining numerical identity (how many objects are involved) and the other, object identification, is that of identifying each object by its perceptual attributes (e.g., which objects are involved). Identifying objects on the basis of perceptual attributes requires binding specific features to generic entities. The development of each of these processes is described separately.

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