In the past years, the question of whether lexical competitors become phonologically coactivated during speech planning has received a lot of attention, as the answer to this question is central to the discussion about serial-discrete versus cascaded models of lexical access (Levelt et al., 1991, 1999; Dell & O'Seaghdha, 1991). Meanwhile it has been experimentally demonstrated that near-synonymous competitors are indeed phonologically coactivated (such as "sofa", when "couch" is the target; Peterson & Savoy, 1998; Jescheniak & Schriefers, 1998), but no such effect has been obtained for non-synonymous semantic competitors (such as "hand", when "foot" is the target, Levelt et al., 1991; Peterson & Savoy, 1998). However, it has repeatedly been pointed out that the available chronometric techniques might not be sensitive enough to reliably detect small phonological coactivation effects that are to be expected under cascaded models also for the latter type of competitors (Dell & O'Seaghdha, 1991; Harley, 1993). We performed a series of experiments using a new event-related brain potential (ERP) paradigm for the study of lexical activation processes during speech production (Jescheniak, Schriefers, Garrett, & Friederici, 2001). It combines a delayed picture naming task with a priming technique. While native speakers of German prepared the naming of an object, they heard an auditory target word to which the ERP was recorded. This auditory target word was related to the prepared picture name in various ways. It was either phonologically related ("Sand" - sand, if "Hand" - hand was the target), or the name of a semantic competitor ("Fuss" -foot), or related to the phonological form of the semantic competitor ("Mus" - pap, mediated semantic-phonological condition). These experiments consistently showed semantic and phonological priming effects, as manifested in less negative going ERP-waveforms in the N400 time window. However, they also consistently demonstrated the absence of mediated semantic-phonological priming, even for the case that the semantic competitor had been named a few trials earlier. These ERP findings are thus in line with the extant behavioral data, further suggesting that mediated semantic-phonological priming does not occur for same semantic category competitors during lexical access.
References
Dell, G. S., & O'Seaghdha, P. G. (1991). Mediated and convergent lexical priming in language production: A comment on Levelt et al. (1991). Psychological Review, 98, 604-614.
Harley, T. A. (1993). Phonological activation of semantic competitors during lexical access in speech production. Language and Cognitive Processes, 8, 291-309.
Jescheniak, J. D., & Schriefers, H. (1998). Serial discrete versus cascaded processing in lexical access in speech production: Further evidence from the co-activation of near-synonyms. Journal of Experimental Psychology: Learning, Memory and Cognition, 24, 1256-1274.
Jescheniak, J. D., Schriefers, H., Garrett, M. F., & Friederici, A. D. (2001). Exploring the activation of semantic and phonological codes during speech production with event-related brain potentials. Submitted for publication.
Levelt, W. J. M., Schriefers, H., Vorberg, D., Meyer, A. S., Pechmann, T., & Havinga, J. (1991). The time course of lexical access in speech production: A study of picture naming. Psychological Review, 98, 122-142.
Levelt, W. J. M., Roelofs, A., & Meyer A. S. (1999). A theory of lexical access in speech production. Behavioral and brain sciences, 22, 1-75.
Peterson, R. R., & Savoy, P. (1998). Lexical selection and phonological encoding during language production: Evidence for cascaded processing. Journal of Experimental Psychology: Learning, Memory, and Cognition, 24, 539-557.