Are non-semantic morphological effects incompatible with a distributed connectionist approach to lexical processing?

On a distributed connectionist approach, morphology reflects a learned sens itivity to the systematic relationships among the surface forms of words an d their meanings. Performance on lexical tasks should thus exhibit graded e ffects of both semantic and formal similarity. Although there is evidence f or such effects, there are also demonstrations of morphological effects in the absence of semantic similarity (when formal similarity is controlled) i n morphologically rich languages like Hebrew. Such findings are typically i nterpreted as being problematic for the connectionist account. To evaluate whether this interpretation is valid, we carried out simulations in which a set of morphologically related words varying in semantic transparency were embedded in either a morphologically rich or impoverished artificial langu age. We found that morphological priming increased with degree of semantic transparency in both languages. Critically, priming extended to semanticall y opaque items in the morphologically rich language (consistent with findin gs in Hebrew) but not in the impoverished language (consistent with finding s in English). Such priming arises because the processing of all items, inc luding opaque forms, is influenced by the degree of morphological organisat ion of the entire system. These findings suggest that, rather than being ch allenged by the occurrence of non-semantic morphological effects in morphol ogically rich languages, the connectionist approach may provide an explanat ion for the cross-linguistic differences in the occurrence of these effects .