Examining the roles of regularity and lexical class in 18–26-month-olds' representations of how words sound

By around 12 months, infants have well-specified phonetic representations for the nouns they understand, for
instance looking less at a car upon hearing ‘cur’ than ‘car’ (Swingley and Aslin, 2002). Here we test whether such
high-fidelity representations extend to irregular nouns, and regular and irregular verbs. A corpus analysis confirms
the intuition that irregular verbs are far more common than irregular nouns in speech to young children.
Two eyetracking experiments then test whether toddlers are sensitive to mispronunciation in regular and
irregular nouns (Experiment 1) and verbs (Experiment 2). For nouns, we find a mispronunciation effect and no
regularity effect in 18-month-olds. For verbs, in Experiment 2a, we find only a regularity effect and no
mispronunciation effect in 18-month-olds, though toddlers’ poor comprehension overall limits interpretation.
Finally, in Experiment 2b we find a mispronunciation effect and no regularity effect in 26-month-olds. The
interlocking roles of lexical class and regularity for wordform representations and early word learning are
discussed.