What does the Wug Test demonstrate about children's language processing?

The Wug Test, designed by linguist Jean Berko Gleason, illustrates that children possess the ability to internalize and apply grammatical rules rather than relying solely on imitation. In this test, children are presented with an invented word, “wug,” and then shown a picture of two of these creatures, asking them to complete the sentence by forming the plural: “Now there are two __.” The children commonly respond with “wugs,” demonstrating their understanding of the regular pluralization rule in English, even though they have never encountered the word before.

This ability to generalize grammatical rules to new, unfamiliar words shows that children have an underlying competence regarding language rules. They are not just repeating phrases they have heard; rather, they are actively using their cognitive capabilities to generate new forms based on their understanding of the language structure. This insight into how children acquire language emphasizes the importance of innate linguistic capacities and the natural ability to learn language through exposure rather than through explicit teaching alone.