Automatic Auditory Processing of English Words as Indexed by the Mismatch Negativity, Using a Multiple Deviant Paradigm

Abstract

The results showed that MMN responses could be elicited by speech stimuli with large, single acoustic deviances, within a multiple deviant paradigm design. This result has positive clinical implications for the testing of subjects who may only tolerate short testing sessions (e.g., pathological populations) in that responses to a wider range of speech stimuli may be recorded without necessarily having to increase session length. The results also demonstrated that MMN responses were elicited by large, single acoustic deviances but not fine acoustic deviances within the speech stimuli. The poor results for the fine acoustic deviances support previous studies that have used single contrast paradigms and found that when carefully controlled methodological designs and strict methods of analysis are applied, robust responses to fine-grained CV syllable contrasts may be difficult to obtain. The enhanced MMN observed in response to the real word deviants among nonword standards may provide further evidence for the presence of long-term neural traces for words in the brain, however possible contextual effects limit the interpretation of these data. Further research is needed to investigate the ability of the MMN response to accurately reflect speech sounds with fine acoustic contrasts, as well as the ability of the MMN to reflect neural traces for words in the brain, before it can be reliably used as a clinical tool in the investigation of spoken word processing in pathological populations.