One of the most challenging areas for the study of lexical representation, and its role in lexical access from speech, is morphological complexity and allomorphy. Cross-linguistic evidence is especially critical here to deconfound language specific and language universal characteristics of lexical representation. Here we report some results from Polish, which has very rich derivational and inflectional morphology, and a widespread system of morphophonological alternations.
A first series of experiments investigate a combinatorial approach to lexical representation in Polish. Experiment 1, using cross-modal priming, probed the representation of stems and affixes. The affixes involved mostly do not occur in English, and range through derivational and aspectual-derivational to diminutive affixes. The data support a combinatorial model of the mental lexicon with stems and affixes stored separately, so that the same morphemes can participate in the representation of many different words. Experiment 2 used an auditory-auditory delayed priming task (designed to dissociate semantic effects from morphological ones) to find out whether semantic compositionality determines combinatorial storage in Polish to the same extent as in English (Marslen-Wilson et al., 1994, '96), as opposed to Semitic languages such as Hebrew (Deutsch et al. 1998) and Arabic (Boudelaa, personal communication). The experiment contrasted words varying in morphological complexity and in semantic transparency. Priming was obtained only for words which were semantically compositional, irrespective of morphological complexity. This suggests that semantic compositionality plays an important role in determining the lexical representation in Polish, with semantically compositional words represented in a combinatorial fashion, and non-semantically compositional words possibly represented as full forms.
A second series of experiments investigated the abstractness of underlying representations in Polish, probing the representation of verbs and nouns with regular and irregular alternations. Again we used both the cross-modal technique (nouns and verbs) and auditory-auditory delayed repetition (verbs). The results indicate that both regular and irregular alternants map onto the same underlying morpheme, with strong priming both immediately and at a delay, regardless of degree and type of alternation. The results overall, which cannot be attributed to either semantic or phonological factors, support a morphemic combinatorial approach to lexical representation, with alternants of the same verb mapping onto the same underlying lexical entry, and with semantic compositionality playing a crucial role in determining the nature of the representation. The results for the Polish mental lexicon correspond to those obtained for English and are in contrast to the results for Hebrew and Arabic. The theoretical implications of this are discussed.