Automatic auditory word perception as measured by 40 Hz EEG responses.

OBJECTIVES Here we report the existence of automatic speech perception in man, revealed by 40 Hz EEG responses. METHODS We presented to Finnish subjects the Finnish word /tu:li/(wind) as the standard stimulus and another Finnish word /tuli/(fire) as the deviant stimulus using a passive auditory oddball task. The experiment was also conducted with pseudowords as stimuli. RESULTS We observed a global significant increase in 40 Hz EEG power at 600 ms after stimulus onset for words, but not for pseudowords. CONCLUSIONS Our results indicate that the memory representation of the standard verbal stimuli, even if unattended, might not merely be based on the physical features of the stimuli: if a semantic representation exists, then the brain processes it pre-attentively.

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