engleski

More than just ‘adding the -ed’: Can we predict verb overgeneralizations in morphologically rich languages?

The acquisition of inflectional morphology can be particularly challenging for children and often leads to the production of incorrect forms, including overgeneralization of a given rule to irregular word forms (e.g., bring to bringed instead of brought in English). Overgeneralized forms reflect the complexity of the morphological system and reveal the strategies children use when confronted with it. Highly inflected languages exhibit some features related to early language acquisition that are not entirely consistent with findings in less inflected languages (Dressler 2005), especially English, which is usually taken as a model to draw inferences about this phenomenon. The Croatian conjugation system displays different degrees of complexity based not only on the number of inflectional morphemes but also on an elaborate system of stem changes. For most verbs it is not sufficient to attach the corresponding affix to the infinitive stem because the infinitive stem and the simple present stem differ in phonological features (cf. šet-a- ti.INF ‘to walk’ and šeć-e-m.PRS.1SG ‘I walk’). During early language development, children are likely to use overgeneralized forms to overcome this complexity. These forms are often used interchangeably with ‘adult-like’ forms (e.g., plesati.INF ‘to dance’ > plesam / plešem.PRS.1SG ‘I dance’), that is, children use more than one form per slot in the morphological paradigm. Both the correct and overgeneralized forms are attested simultaneously, but not with the same frequency. In the research on the acquisition of inflectional morphology, two main factors influencing overgeneralization can be identified – token frequency (how often a child is exposed to a particular verb form) and phonological neighbourhood density or class size (the number of verbs with phonologically similar word stems bearing the same corresponding inflectional morpheme). However, not many studies investigated the influence of these factors in morphologically rich languages, especially on the acquisition of verbal morphology (cf. Kirjavainen, Nikolaev & Kidd 2012 ; Engelmann et al. 2019). The aim of this study was to investigate the production of overgeneralized verb forms in preschool Croatian- speaking children aged 2 ; 6 to 5 ; 11 using a questionnaire in which parents report overgeneralizations in the language of their children. We hypothesized that parents will report overgeneralized forms in all verb classes in which the stem changes, but that the frequency of overgeneralizations will depend on the features of the input, i.e. it will correlate with the frequency of verbs (higher rate of overgeneralizations for infrequent verbs) and class size in lemmas, tokens and tokens of selected verb types (higher rate of overgeneralizations for verbs with smaller class size). To date, studies have used a corpus-based method to retrieve overgeneralizations in child language, which has had limited success in capturing this phenomenon due to the low density of language sampling and low-frequency phenomena such as overgeneralizations tend to be underrepresented. A parental questionnaire could provide more precise information about the overgeneralization of verb forms. The verbs for the questionnaire were selected from the longitudinal Croatian corpus of child language (Kovačević 2002) to ensure that they occur in child-directed speech (CDS). To refine the selection, we used two lexical databases that contain information on the estimated age of acquisition and subjective word frequency retrieved from native speakers. A total of 36 verbs were included in the study. For each verb, two items were created: the ‘adult-like’ form and the overgeneralized form. The frequency of verbs was calculated from the longitudinal child language corpus (CDS) and corpus of written adult language (hrWaC, Ljubešić & Klubička 2014). We obtained two types of frequency information for each of the preselected verbs: the overall frequency of all morphological types of a verb and the frequency of specific morphological types of a verb that were central to our study. The class size was calculated from the same sources in lemmas, tokens and tokens of selected types. Parents were asked to indicate how often their child produces a particular verb form using a 5- point Likert scale. Altogether, 87 parents completed the online questionnaire, therefore, we obtained data for 87 children. The results showed that parents reported overgeneralized forms in child language for all verbs included in the questionnaire. We found a negative relationship between the proportion of overgeneralized forms and the overall verb frequency in both CDS and hrWaC. Verbs with a lower frequency have a higher proportion of overgeneralized forms. We also found a negative relationship between the class size in tokens (CDS) and both the frequency of overgeneralized forms and the proportion of overgeneralized forms. The same results were found for the class size in specific morphological types of a verb (hrWaC). The frequency of overgeneralized forms and the proportion of overgeneralized forms are lower in larger classes, that is, in classes that are more frequent in the language surrounding children. The frequency and class size showed better correlations with the measures in the questionnaire when calculated on tokens of specific morphological forms, i.e. those where overgeneralization is expected. Our results are consistent with previous studies that have confirmed a facilitating effect of frequency and class size on the acquisition of inflectional morphology (e.g., Kirjavainen, Nikolaev & Kidd 2012 ; Engelmann et al. 2019). The present study reveals that preschool children still resort to the mechanism of overgeneralizations to overcome the complexity of verbal morphology.

first language acquisition ; overgeneralization ; verbs ; Croatian ; frequency ; class size

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