Mismatch negativity effects of alternating vowels in morphologically complex word forms

In some languages, morphologically complex word forms may involve vowel alternations between front and back phonemes, as illustrated in the German noun Stock (Stock∼Stöcke ‘stick∼sticks’) versus the non-alternating Stoff (Stoff∼Stoffe ‘cloth∼cloths’). This study was aimed to investigate the consequences of the presence or absence of these alternations for the fine structure of lexical representations. Previous research has shown that certain vowel oppositions are processed in an asymmetric way, as studied by means of brain electric activity (e.g. Eulitz & Lahiri, 2004). Here, we contrasted base form and diminutive stems of German nouns in a Mismatch Negativity (MMN) study. We compared the alternating noun Stock with non-alternating Stoff and obtained a consistently stronger MMN if Stoff was preceded by a fronted stem. This was an initial stem fragment in Experiment 1 and its diminutive form in Experiment 2. The results of our experiments indicate asymmetries in processing at the phonetics/morpho-phonology interface and are discussed on the background of several models of lexical representation and morphological processing. We conjecture that our findings are best explained by differences in abstract phonological representations.