OVERREGULARIZATION IN ENGLISH PLURAL AND PAST TENSE INFLECTIONAL MORPHOLOGY - A RESPONSE TO MARCUS (1995)

In a recent note, Marcus (1995) suggests that the rate of overregulari zation of English irregular plural nouns is not substantively differen t from that of English irregular past tense verbs. This finding is cla imed to be in conflict with the predictions of connectionist models (P lunkett & Marchman, 1991, 1993) which are said to depend solely on the dominance of regular over irregular forms in determining overregulati on errors. However, these conclusions may be premature given that Marc us averaged overregulation rates across irregular nominal forms that v aried in token frequency and across samples representing a broad range of children's ages. A connectionist view would predict an interplay b etween type frequency and other item level factors, e.g. token frequen cy, as well as differences in the developmental trajectories of the ac quisition of nouns and verbs. In this response, we briefly review long itudinal parental report data (N = 26) which indicate that children ar e significantly more likely to produce noun overregularizations than v erb overregularizations across a prescribed age period (1;5 to 2;6). A t the same time, these data also show that children are familiar with proportionately more irregular nouns than irregular verbs. These findi ngs are consistent with the predictions of Plunkett & Marchman (1991, 1993) in that the larger regular class affects the frequency of noun e rrors but also that familiarity with individual irregular nouns tends to reduce the likelihood of overregularizations. In contrast to the co nclusion of Marcus (1995), the connectionist approach to English infle ctional morphology-provides a plausible explanation of the phenomenon of overregularization in both the English plural and past tense system s.