Object permanence: The understanding that an object still exists even if it can't be seen or heard. For example, a child knows that a toy still exists under a blanket even though they can't see it.
Stranger anxiety: The fear or wariness that infants often display when encountering unfamiliar people. It is common during the sensorimotor stage as babies become more aware of social interactions.
Egocentrism:The inability to understand or consider other people's perspectives. In this stage, infants are primarily focused on their own experiences and have difficulty understanding others' viewpoints.