Cholin, J. 1 , Rapp, B. 2 & Miozzo, M. 2, 3
1 Basque Center on Cognition, Brain and Language (BCBL). Donostia. Spain.
2 Johns Hopkins University, Baltimore, USA
3 Cambridge University, UK
In a number of languages, inflected words are generally distinguished in the following way: so-called regular words show predictable stem-affix combinations, whereas so-called irregular words take idiosyncratic, generally unpredictable forms. Cross-linguistically, irregular words come in a variety of kinds. In a language like English, irregularity is reflected by stem changes (bring -> brought; run -> ran). In contrast, in many other languages, including German or Italian, stems as well as inflections of irregularly inflected words can deviate from regular, default patterns. For example, the German irregular past-participle form geschwommen [swam] takes the stem schwomm (instead of the infinitive stem schwimm) and the affix –en (instead of the irregular affix –t). Theories of language processing generally agree that irregularly inflected words recruit mechanisms that are distinct from those engaged by regularly inflected words. Consistent with this proposal, irregularly inflected words were found to be specifically impaired in individuals with acquired language deficits, particularly lexical-access deficits. The lexical deficits observed in bilingual individuals offer a unique opportunity to investigate whether the fundamental differences of irregular verb generation reflect differences in the underlying processing in these languages. We examine this issue in the present investigation of WRG, a bilingual German-English aphasic individual who suffered primarily from a lexical-retrieval deficit. Regular and irregular verb inflections were elicited using a sentence-completion task, both in English and German. The results showed a remarkably similar pattern in the two languages: responses were more accurate for regular than irregular verbs. We interpreted these results as reflecting the involvement of similar lexical mechanisms in the processing of irregular words in English and German. In English, such a lexical deficit affects the retrieval of stems, whereas in German it impairs the retrieval of both stems and affixes. These conclusions were further supported by detailed analyses of WRG’s errors.