Effects of the azimuthal position of stationary and moving sound images on the mismatch negativity phenomenon.

This report presents results obtained from studies of the phenomenon of mismatch negativity in conditions of dichotic stimulation with presentation of deviant stimuli modeling movement of a sound image towards or away from a standard stimulus and on presentation of stationary deviants located at an angle of 90 degrees to the standard. Standard stimuli were located close to the left or right ear or in the midline of the head. All deviant stimuli induced mismatch negativity. Movement of the deviant stimulus from the standard was found to induce mismatch negativity with the longest latency and smallest amplitude for all azimuthal positions of the standard stimulus. In addition, it was only in this direction of movement that there was a relationship between measures of mismatch negativity and the azimuth of the standard. It was suggested that the process of the recognition of differences between interaural delay times is significantly dependent on the nature of changes in this parameter at the moment at which the deviant stimulus is presented.