Wug Test - Jean Berko Gleason (1958)

• The researcher shows a child cards with drawings of imaginary animals, and teaches the child a nonsense name for the animal.
• The researcher says, "This is a wug. Now there is another one. There are two of them. There are two wugs."
• Very young children are baffled by the question and are unable to answer correctly, sometimes responding with "two wug".
• Children aged 4-5 test best in dealing with /z/ after a voiced consonant, and generally say that there are two wugs, with a /z/; they do almost as well with the voiceless /s/.
• Children below the age of 4 do less well in dealing with /z/ in other environments such as after nasals and vowels.
• The Wug Test also includes questions that explore a child's understanding of verb inflections and the possession.
• Additional items were designed to investigate children's ability to handle common derivational bound morphemes such as the agentive -er. (a man who works = worker)