Stem overgeneralizations in the acquisition of Croatian verbal morphology: Evidence from parental questionnaires

Studies on verbal overgeneralization often focus on languages with low morphological complexity. The Croatian conjugational system exhibits varying degrees of complexity, and this complexity is not primarily based on the number of inflectional morphemes, but on an elaborate system of stem changes. During early language development, children face the difficult task of acquiring this system, using overgeneralized forms to overcome its complexity. To date, studies have used a corpus-based method to retrieve overgeneralizations in child language, which has had limited success in capturing this phenomenon. The aim of this study was to investigate the production of overgeneralized verb forms in Croatian monolingual children aged 2;6 to 5;11 using a questionnaire in which parents report overgeneralizations used by their children. We tested the relationship between the production of overgeneralized forms and features of the input language (token frequency and class size). We hypothesized that the rate of overgeneralizations will depend on input language features, i.e. a higher rate of overgeneralizations for infrequent verbs and for verbs with smaller class size. The items selected for the questionnaire are the verbs with stem change used by parents in the longitudinal Croatian corpus of child language. Parents report overgeneralized forms in all verb classes, and verb frequency and class size negatively correlate with the proportion of overgeneralizations. Our results show that children gradually abstract morphological systems in a way that is highly sensitive to the properties of the input.