Why do children sometimes say words such as doggie for several different animals?

When children use a word like "doggie" to refer to several different animals, they are engaging in a common aspect of language acquisition known as overextension. This occurs because young children are in the process of concept formation, where they learn to symbolize and represent the world around them using words and gestures.1

During the early stages of developmental psychology, specifically the sensorimotor and representative intelligence stages identified by Jean Piaget, children rely on trial and error to categorize their environment. Because their vocabulary is still limited, they often apply a known label to new objects that share similar characteristics, such as four legs or fur. As their cognitive skills and vocabulary grow, they refine these associations to distinguish between different animals more accurately. This process is a natural part of developing meaningful speech as they move beyond simple imitation toward true comprehension.1