Competitive processes during word-form encoding

Abstract

Abstract: A highly constrained model of phonological encoding, which is minimally affected by the activation levels of alternative morphemes and phonemes, is proposed. In particular, weaver11predicts only facilitatory effects on word production of the prior activation of form related words. However, inhibitory effects of form priming that suggest that a more strongly competitive system is required exist in the literature. Despite superficial similarities, the approach taken by Levelt, Roelofs & Meyer to the problem of word-form encoding differs fundamentally from previous attempts to model this process. This difference hinges on the attitude taken to noise in the system. The encoding of most words occurs within a sea of activated alternative morphemes and their constituent sublexical representations. Some of this activation comes from external sources such as the speech of others or written language. Some activation will be generated directly by the utterance to be produced (i.e., the residual activation of the morphemes just articulated and the anticipatory activation of those to be generated). There is also activation of words that do not form part of the intended utterance but are related in form to a word to be produced (e.g., malapropisms: saying “apartment” when you intended to say “appointment”). Traditionally, models of word-form encoding have used this riot of background activation to explain how speech errors can occur by incorporating selection mechanisms that are sensitive to the activation levels of alternative representations. In Dell’s (1986) model, the selection of a given phoneme is determined by its level of activation during an ordinal selection process. Alternatively, inhibitory or competitive mechanisms have been proposed. Stemberger (1985) postulates inhibition between form-related lexical representations activated by feedback from shared phonemes. Sevald and Dell (1994) propose competition between activated phonemes during a left-to-right assignment process of segments to frames. In contrast, Levelt et al. postulate no competitive selection process at the morpheme level and no feedback of activation from phonemes to morphemes. In addition, the selection by checking device employed in weaver11 divorces the selection and encoding of phonemes from their level of activation, thereby ensuring that encoding runs correctly regardless of the activation levels of alternative phonemes. weaver11 restricts competition to phonetic encoding processes but even here the activation of form related morphemes will speed encoding of the target by increasing the numerator of the access ratio for the target syllables compared with unrelated syllable programs. The strict limitations on activation spreading and competition