Wug test

The Wug Test was created by Jean Berko Gleason in 1958. It was designed as a way to analyze the acquisition of the plural and other inflectional morphemes in English-speaking children.

There are three plural allomorphs in English: /z/, the most general form (dogs, /dAgz/); /s/, which appears after voiceless consonants (cats /k}ts/); and /@z/, which appears after sibilants (horses, /hOrs@z/).

The child is presented with some sort of pretend creature, and told, "This is a wug." Another wug is revealed, and the researcher says, "Now there are two of them. There are two...?" Children who have successfully acquired the allomorph /z/ of the plural morpheme will respond: wugs /wVgz/ (see SAMPA for phonetic symbol key).

Very young children are baffled by the question and are unable to answer correctly, sometimes responding with "Two wug." Preschoolers aged 4 to 5 test best in dealing with /s/ and /z/ after a voiced consonant; less well in dealing with /z/ in other environments such as after nasals, rhotics, and vowels. Children in grade 1 were almost fully competent with both /s/ and /z/. Both preschool and first-grade children dealt poorly with /@z/, giving the correct answer less than half the time, possibly because it occurs in the most restrictive context.

The Wug Test also includes questions that determine a child's understanding of verb conjugation and the possessive. Additional items were designed to investigate children's ability to handle common derivational morphemes such as the agentive -er (a man who "zibs" is a ....?). A final series of questions called on the children to explain common compound words in their vocabulary ("Why is a birthday called a birthday?") Very young children (preschoolers) form compounds rather than agentives with -er. They say that a man whose job is to "zib" is a "zibman". Young children also explain compound words in terms of their salient features: they respond that a birthday is called "birthday" because you get presents.

The original Wug Test is reported in Jean Berko Gleason's article "The Child's Learning of English Morphology," Word 14:150-77 (1958).