Interference and facilitation in spoken word production: effects of morphologically and semantically related context stimuli on picture naming.

We report two picture-word interference experiments investigating conceptual and lexical activation, and response selection, in speaking. We varied stimulus onset asynchrony to investigate potential fine-grained activation and competition effects. Morphologically related existing and pseudoword adjectives, as well as associatively related adjectives, served as context stimuli in Experiment 1. In Experiment 2, we focused on semantic interference by using morphologically related and unrelated subordinates of the target concept as context stimuli. Morphologically complex pseudowords were also included as context stimuli. Pseudowords should not interfere, given that they have no lexical or conceptual representation. We consistently obtained facilitation with all morphologically related context stimuli, irrespective of their lexical status. We argue that effects originate at the word-form level, and discuss how our results may help decide among the many explanations of semantic interference in picture naming.