Two experiments investigated whether lexical retrieval for speaking can be characterized as a competitive process by assessing the effects of semantic context on picture and word naming in German. In Experiment 1 we demonstrated that pictures are named slower in the context of same-category items than in the context of items from various semantic categories, replicating ®ndings by Kroll and Stewart (Journal of Memory and Language, 33 (1994) 149). In Experiment 2 we used words instead of pictures. Participants either named the words in the context of same-or different-category items, or produced the words together with their corresponding determiner. While in the former condition words were named faster in the context of samecategory items than of different-category items, the opposite pattern was obtained for the latter condition. These ®ndings con®rm the claim that the interfering effect of semantic context re¯ects competition in the retrieval of lexical entries in speaking. q

The relationship between semantic-syntactic and phonological levels in speaking was investigated using a picture naming procedure with simultaneously presented visual or auditory distractor words. Previous results with auditory distractors have been used to support the independent stage model (e.g., H. Schriefers, A. S. Meyer, & W. J. M. Levelt, 1990) whereas results with visual distractors have been used to support an interactive view (e.g., P. A. Starreveld & W. La Heij, 1996b). Experiment 1 demonstrated that with auditory distractors semantic effects preceded phonological effects whereas the reverse pattern held for visual distractors. Experiment 2 indicated that the results for visual distractors followed the auditory pattern when distractor presentation time was limited. Experiment 3 demonstrated an interaction between phonological and semantic relatedness of distractors for auditory presentation, supporting an interactive account of lexical access in speaking.

In the cyclic semantic blocking paradigm participants repeatedly name sets of objects with semantically related names ( homogeneous sets) or unrelated names ( heterogeneous sets). The naming latencies are typically longer in related than in unrelated sets. In Experiment 1 we replicated this semantic blocking effect and demonstrated that the effect only arose after all objects of a set had been shown and named once. In Experiment 2, the objects of a set were presented simultaneously (instead of on successive trials). Evidence for semantic blocking was found in the naming latencies and in the gaze durations for the objects, which were longer in homogeneous than in heterogeneous sets. For the gaze-to-speech lag between the offset of gaze on an object and the onset of the articulation of its name, a repetition priming effect was obtained but no blocking effect. Experiment 3 showed that the blocking effect for speech onset latencies generalized to new, previously unnamed lexical items. We propose that the blocking effect is due to refractory behaviour in the semantic system.

In a size judgment task on words denoting concrete objects, subliminally presented stimuli that preceded the targets influenced response times and were dependent on whether responses to the prime and the target were congruent or incongruent (Experiment 1). These findings, mirroring S. Dehaene et al. (1998), imply that primes are unconsciously categorized and processed to the response stage. However, the effect does not generalize to primes that are not in the response set (Experiment 2), and even exposure to primes not in the response set in an interleaved naming-size judgment task fails to induce it (Experiment 3). However, the effect generalizes from lowercase primes to the same set of uppercase targets (Experiment 4), suggesting an abstract level of operation. The findings suggest that rather than resulting from unconscious prime categorization, the congruity effect results from automatized stimulus-response mappings. Potential differences between the number and the word domain are discussed.

A number of recent studies have found that objects are named more slowly in the context of same-category items than in the context of items from various semantic categories. Several experiments reported here indicated that this semantic effect is relatively persistent because it was essentially unaffected by the presence of interspersed filler items. The authors suggest that the effect is specific to the retrieval of lexical-semantic codes and characterize mechanisms that could support the effect at this processing level, such as incremental learning in the links between conceptual and lexical codes and the temporary increase of lexical resting levels. The results underscore the necessity of incorporating mechanisms of long-term adaptation into current models of spoken production.