An Electroencephalography Investigation of the Effects of Attention on Crossmodal Temporal Acuity

Science Center, Bent Corridor

Our perception of the world hinges on our ability to accurately combine the many stimuli in our environment. This multisensory integration is highly dependent on the temporal relationship between unisensory events and our brain’s ability to discern small timing differences between stimuli (crossmodal temporal acuity). Our previous research investigated whether attention alters crossmodal temporal acuity using a crossmodal temporal order judgment (CTOJ) task in which participants were asked to report if a flash or beep occurring at different time intervals appeared first while concurrently completing a visual distractor task. We found that increasing the difficulty (perceptual load) of the distractor task lead to sharp declines in participants’ crossmodal temporal acuity. The current study uses electroencephalography (EEG) to understand the neural mechanisms that lead to decreased crossmodal temporal acuity. Participants completed a CTOJ task as described above while EEG activity was recorded from electrodes positioned on the scalp. EEG activity was averaged based on the onset of the flash producing an event-related potential (ERP) waveform for each perceptual load level. The ERP waves show peaks in activity over time, allowing us to interpret neural activity across the scalp, and correspondingly in the brain. The amplitude of early peaks (P1, N1), typically associated with sensory processing, decreased in amplitude with increasing perceptual load. However, we saw the opposite effect for later peaks (P2) suggesting a delayed compensation for early effects of distraction. This line of research could ultimately help our understanding of the disruptions in temporal acuity often found in attentional disorders.