Errors of Omission in English-Speaking Children's Production of Plurals and the Past Tense: The Effects of Frequency, Phonology, and Competition.

How do English-speaking children inflect nouns for plurality and verbs for the past tense? We assess theoretical answers to this question by considering errors of omission, which occur when children produce a stem in place of its inflected counterpart (e.g., saying "dress" to refer to 5 dresses). A total of 307 children (aged 3;11-9;9) participated in 3 inflection studies. In Study 1, we show that errors of omission occur until the age of 7 and are more likely with both sibilant regular nouns (e.g., dress) and irregular nouns (e.g., man) than regular nouns (e.g., dog). Sibilant nouns are more likely to be inflected if they are high frequency. In Studies 2 and 3, we show that similar effects apply to the inflection of verbs and that there is an advantage for "regular-like" irregulars whose inflected form, but not stem form, ends in d/t. The results imply that (a) stems and inflected forms compete for production and (b) children generalize both product-oriented and source-oriented schemas when learning about inflectional morphology.