Minsu Ryu, Kazunari Ikeda
Infrequent pitch changes can usually elicit an electroencephalography (EEG) response, the mismatch negativity (MMN). By using a fixed five-tone sequence (AAAAB) composed of two pitches (A and B), Sussman and Gumenyuk (2005) found that the repetition of AAAAB patterns with a narrow stimulus onset asynchrony (SOA), but without inter-group intervals, eliminated the MMN to B tones. They attributed those outcomes to sensory memory formation of the AAAAB sequence. On the other hand, many studies have revealed the enhanced MMN to sound groups by introducing inter-group intervals. In the current study, we compared two experimental conditions with and without inter-group intervals for the research paradigm of Sussman and Gumenyuk (2005). With inter-group intervals, the AAAAB pattern repetition did not prevent the MMN elicitation to B tones for any SOA. Without inter-group intervals, however, the MMN to B tones was reduced for narrow SOAs. Considering the role of inter-group intervals as an enhancer of an auditory group representation, the present outcomes were interpreted.