Naming a picture is slower while ignoring a semantically related versus an unrelated distractor word (semantic picture-word interference, or PWI). To locate the PWI effect in the word production processing stream (during perceptual encoding, response selection, or afterward), we used the psychological refractory period paradigm, in which participants identified a tone and then, at varying SOAs, named a picture while ignoring a semantically related or unrelated word (following Dell 'Acqua, Job, Peressotti, & Pascali, 2007). As in results from the Stroop paradigm (Fagot & Pashler, 1992), we found equivalent PWI effects at short and long SOAs following tone identification in two experiments, indicating that semantic competition occurs at response selection or later. Our results suggest that it is premature to assume that competitive selection occurs at multiple levels in the word production system (van Maanen, van Rijn, & Borst, 2009) or that the Stroop and semantic PWI effects are fundamentally different (Dell'Acqua et al., 2007).Keywords Psychological refractory period . Speech production . Picture-word interference paradigm In order to study word production, several well-studied methods have manipulated the difficulty with which we choose a word by increasing the availability of competitor words. We are generally slower when naming the presentation color of a word that spells a different color name (e.g., saying "black" when seeing WHITE vs. saying "black" when seeing BLACK; i.e., Stroop interference: Stroop, 1935). Likewise, we are generally slower when naming a picture of a "dog" while concurrently seeing the displayed word RABBIT rather than the word TABLE (semantic interference in the pictureword interference paradigm; see, e.g., Lupker, 1979).In both paradigms, the delay to choose the appropriate word to name is generally explained in similar ways (e.g., Roelofs, 2003). We are slower to produce the name (color/ picture) in the presence of words that are semantically related rather than unrelated to the target because the related distractor words receive priming from both the target's meaning and the printed distractor. Because the target name is selected on the basis of its activation level relative to the activation of other words in the lexicon, when competitors have increased activation, target selection takes more time (e.g., Roelofs, 1992; cf. Mahon, Costa, Peterson, Vargas, & Caramazza, 2007). This interference effect is thought not to occur during the identification of what meaning we need to convey (e.g., "black" or "dog"), but afterward, during response selection (Roelofs, 1992) or response execution (the prearticulatory buffer; Mahon et al., 2007).One source of evidence for the response selection locus of the Stroop effect comes from the psychological refractory period (PRP) paradigm. The PRP paradigm can be used to determine where the components of task processing occur during performance-for example, during stimulus perception, or afterward, during the selection and execution of the a...