A single route, full decomposition model of morphological complexity: MEG evidence

Against longstanding assumptions in the psycholinguistics literature, we argue for a model of morphological complexity that has all complex words assembled by the grammar from lexical roots and functional morphemes. This assembly occurs even for irregular forms like gave. Morphological relatedness is argued to be an identity relation between repetitions of a single root, distinguishable from semantic and phonological relatedness. Evidence for the model is provided in two MEG priming experiments that measure root activation prior to lexical decision. Both regular and irregular allomorphs of a root are shown to prime the root equally. These results are incompatible both with connectionist models that treat all morphological relatedness as similarity and with dual mechanism models in which only regular forms involve composition.