Inflectional Morphology: The study of inflectional morphology has played an important role in cognitive psychology ever since Jean Berko demonstrated in the 1950s that young children can inflect novel words in the well-known wug test. In this test, children are shown the picture of a single novel object and told that it is, say, a ‘wug’. They are then shown a picture of two such objects and prompted to name them ‘Here are two ????’. Berko showed that children are highly likely to pluralise the novel word by adding an `s'. This suggested that even 4 or 5 year-old children are able to identify subtle regularities in language and use them in a creative way. Language learning is not merely a question of imitating what you hear.