Evidence that the mismatch negativity system works on the basis of objects.

The purpose of this study was to determine whether the system that underlies the mismatch negativity (MMN) of event-related potentials would operate on the basis of objects if stimuli were delivered in such a way as to create the impression of two objects. To this end, tones were alternated between ears with one combination of features for each ear. Deviant tones, which differed from the standard tones of both ears, were delivered separately to each ear. The deviants elicited MMNs only with respect to the standards of the ear to which they were delivered. The data indicate that the MMN system operated on the basis of objects and that the integration of objects occurs preattentively in the auditory system.