What “Mice Trap” tells us about the mental lexicon

Level ordering has proven inadequate as a morphological theory, leaving unexplained the experimental results taken to support it as a component of innate grammar—young children’s acceptance of irregular plurals in English compounds. The present study demonstrates that these results can be explained by slower access to the grammatically preferred singulars of irregular nouns when compounds are created on-line from plural stimuli. Experiments on English noun–noun compound production and on production of either singular or plural forms from the same or opposite form confirmed that more irregular than regular plurals were used in compounds, and showed that producing irregular singulars from plurals was slower than producing regular singulars. Plural responses were also slower when cue and required response number differed.