Lexical Retrieval is not by Competition: Evidence from the Blocked Naming Paradigm.

A central issue in research on speech production is whether or not the retrieval of words from the mental lexicon is a competitive process. An important experimental paradigm to study the dynamics of lexical retrieval is the blocked naming paradigm, in which participants name pictures of objects that are grouped by semantic category ('homogenous' or 'related' blocks) or not grouped by semantic category ('heterogeneous' or 'unrelated' blocks). Typically, pictures are repeated multiple times (or cycles) within both related and unrelated blocks. It is known that participants are slower in related than in unrelated blocks when the data are collapsed over all within-block repetitions. This semantic interference effect, as observed in the blocked naming task, is the strongest empirical evidence for the hypothesis of lexical selection by competition. Here we show, contrary to the accepted view, that the default polarity of semantic context effects in the blocked naming paradigm is facilitation, rather than interference. In a series of experiments we find that interference arises only when items repeat within a block, and only because of that repetition: What looks to be 'semantic interference' in the blocked naming paradigm is actually less repetition priming in related compared to unrelated blocks. These data undermine the theory of lexical selection by competition and indicate a model in which the most highly activated word is retrieved, regardless of the activation levels of nontarget words. We conclude that the theory of lexical selection by competition, and by extension the important psycholinguistic models based on that assumption, are no longer viable, and frame a new way to approach the question of how words are retrieved in spoken language production.