Pattamadilok, C. 1 , Colin, C. 1 , Morais, J. 1 & Kolinsky, R. 1, 2
1 Université Libre de Bruxelles, Belgium
2 Fonds de la Recherche Scientifique-FNRS, Belgium
Behavioral and brain-imaging studies demonstrated the influence of orthographic knowledge on active and high-level speech processing tasks even when written words are not presented. No studies, however, have successfully shown that such influence could be observed at a very low processing level: when speech is unattended. Here, the Mismatch Negativity, a specific ERP component that is an automatic index of experience-dependent auditory memory traces, was used to investigate this issue. An ‘‘odd-ball’’ sequence of acoustic stimuli containing a frequent-standard word /tRi/-“TRI”, an orthographically congruent infrequent-deviant word, /kRi/-“CRI”, and an orthographically incongruent infrequent-deviant word, /pRi/-“PRIX”, was presented to 14 participants in a passive listening situation where participants watched silent movies and ignored the auditory stimuli. Both deviant words elicited a typical MMN over the fronto-central regions, reflecting automatic discrimination of standard and deviant stimuli. Most interestingly, the MMN elicited by the orthographically incongruent deviant word showed higher peak and mean amplitude than the one elicited by the orthographically congruent deviant word. We concluded that orthographic knowledge qualitatively changes the nature of spoken words. Once reading is acquired, the “phonological” representations might become “phonographic” representations. The implication of this observation on the architecture of the speech processing models will be discussed.