What concept is demonstrated when D'Andre begins to search for a toy train after it is hidden?

The concept demonstrated when D'Andre begins to search for a toy train after it is hidden is object permanence. This cognitive milestone is a key part of developmental psychology, particularly in understanding how infants and toddlers perceive the world around them. Object permanence refers to the understanding that objects continue to exist even when they cannot be seen, heard, or otherwise sensed.

In this scenario, D'Andre searching for the train indicates that he has developed the ability to mentally represent the hidden object, which signifies that he recognizes the train still exists even though it is no longer visible. This realization typically emerges during the sensorimotor stage of cognitive development, as outlined by developmental theorist Jean Piaget, usually around 8 to 12 months of age.

The other concepts listed—symbolic thinking, conservation, and egocentrism—address different aspects of cognitive development. Symbolic thinking involves the ability to use symbols or mental representations, conservation is the understanding that certain properties of objects remain the same despite changes in form or arrangement, and egocentrism refers to the inability to understand a situation from another person's point of view. However, none of these pertain directly to the realization that an object hidden from view continues to exist, which is the central idea of