Independent processing of changes in auditory single features and feature conjunctions in humans as indexed by the mismatch negativity

The mismatch negativity (MMN), an event-related potential component of the EEG, is elicited by violations of auditory regularities. In the present study, the stimulus blocks contained two types of standard tones, differing from each other in frequency and intensity. MMNs were recorded to three different types of deviant stimuli: (a) feature deviants, differing from standards in their perceived locus of origin; (b) conjunction deviants, having the frequency of one of the sta nda rds and the intensity of the other; (c) double deviants, differing from standards in both (a) and (b). The MMN to double deviants was similar to the sum of the MMNs to feature and conjunction deviants. This result indicates that changes in simple stimulus features and conjunction of features are processed independently by the automatic sound change detection system indexed by MMN. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.