Behavioural and ERP effects of paradigm complexity on visual word recognition

Abstract

Are words with form variations in the stem (e.g. foot ~ feet) perceptually processed in the same way as those without (e.g. table)? The majority of psycholinguistic literature concerning (ir)regular morphology concentrates on the processing or storage of inflected forms (e.g., feet vs. tables or thought vs. walked) in relation to their base forms. This article discusses the recognition of base forms of words in relation to their paradigmatic complexity (stem allomorphy). Do words like foot have some benefits in their recognition because of stem allomorphy, or do they rather cause an inhibition effect because of competition in form variation? Or could it be that there is no activation of the allomorph feet when we process the word foot, and thus no influence on the base form? With these and related questions in mind, we investigated the temporal dynamics of processing Finnish monomorphemic nouns with rich stem allomorphy versus nouns with no variation in stem by conducting an event-related potential (ERP) experiment during a single word lexical decision task. Behaviourally and in the ERP data, items with rich stem allomorphy received shorter latencies than the items without stem variation. In the ERP data, the difference waveform between the two word types shows a centro-parietal N400 component consistent with the view that any factor that facilitates lexical access should reduce the N400 amplitude. On the other hand, the global field power waveforms derived from the ERP data give some support to our hypothesis that the brain allocates more processing power to the items with rich stem allomorphy. To explain this response pattern, we conjecture that activation of stem allomorphs at the lemma level facilitates lexical access from form to meaning.