What is "object permanence," and at what stage is it developed?

Object permanence refers to the understanding that objects continue to exist even when they are not visible. This cognitive milestone is a key component of cognitive development and indicates a significant shift in a child's understanding of the world around them.

During the sensorimotor stage, which spans from birth to about 2 years of age, infants learn about their environment primarily through their senses and actions. It is within this stage that they begin to develop the concept of object permanence. Initially, young infants may not realize that when an object is out of sight, it still exists. As they progress through this stage, they begin to search for hidden objects, demonstrating their understanding that these objects have an existence independent of their perception.

The development of object permanence is crucial as it forms the foundation for later cognitive skills, including memory and the ability to understand more complex concepts about the world.