ERPs and attention: Deep data, broad theory

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-independent) neural mismatch process between the sensory input and a memory trace encoding the physical features of the standard stimulus. The MMN independence of attention was addressed in the present study. Standard stimuli and two types of deviant stimuli, differing from standards in frequency either "widely" (5%) or "slightly" (3%) were dichotically 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 stimuli was also included. Even in the present attend conditions with very strong attentional focus, the MMN was elicited by the slight deviants in the unattended input stream. Furthermore, its amplitude was similar to that of the MMN elicited by the equivalent deviant stimuli during reading. The results suggest that auditory frequency is fully analyzed even in the absence of attention.

Attention and mismatch negativity

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-independent) neural mismatch process with a memory trace that encodes the physical features of the standard stimulus. The proposed MMN independence of attention was addressed in the present study. Standard stimuli and two types of deviant stimuli, differing from standards either in frequency or intensity, were dichotically presented in random order and at a rapid rate. The subject attended either to left- or right-ear stimuli, counting the number of a designated type of deviants in that ear. In the present conditions of very strongly focused attention, the MMN was elicited even by frequency change in the ignored input stream, and its amplitude was very similar to that of the MMN elicited by equivalent deviant stimuli (targets) in the attended input stream. In contrast, the MMN to intensity deviation was clearly attenuated in the absence of attention. This effect is, however, probably due to the attention effect on the MMN generator itself rather than the antecedent sensory-analysis and -storing functions.