MISMATCH NEGATIVITY TO SLIGHT PITCH CHANGES OUTSIDE STRONG ATTENTIONAL FOCUS

The mismatch negativity (MMN) component of the auditory event-related potential (ERP) is elicited by infrequent, physically deviant stimuli in a sequence of frequent homogeneous stimuli (''standards''). It has been suggested that the MMN is generated by an automatic (attention-in -dependent) neural mismatch process between the sensory input and a me mory trace encoding the physical features of the standard stimulus. Th e MMN independence of attention was addressed in the present study. St andard stimuli and two types of deviant stimuli, differing from standa rds in frequency either ''widely'' (5%) or ''slightly'' (3%), were dic hotically presented in random order at a very rapid rate. The subject attended either to left- or right-ear stimuli, counting the number of ''slight deviants'' in that ear. A reading condition with the same sti muli was also included. Even in the present attend conditions with ver y strong attentional focus, the MMN was elicited by the slight deviant s in the unattended input stream. Furthermore, its amplitude was simil ar to that of the MMN elicited by the equivalent deviant stimuli durin g reading. The results suggest that auditory frequency is fully analyz ed even in the absence of attention.