An Electrophysiological Study on Intra- and Inter-modal Duration Discrimination: Effects of Performance Level

Duration discrimination is severely impaired when the duration markers are delivered from different sensory modalities (inter-modal) instead of from the same modality (intra-modal). The present study examined the brain activity related to this impairment using eventrelated potentials. Durations were marked either by two auditory signals (AA) or by an auditory and a visual signal (AV), and there were two levels of discrimination difficulty (easy and difficult). A negative component (contingent negative variation) which appeared between the two markers at fronto-central sites and is said to be related to time perception, was larger for AA than for AV, and was not influenced by discrimination difficulty. A principal component analysis showed that the first and the third principal component captured differences in brain activity patterns between sensory modalities and difficulties, whereas the second principal component could reflect brain activity related to time perception in general, regardless of the modalities.