Attending points in time and space.

Both spatial and temporal attention improves auditory processing and these effects seem to originate at perceptual processing stages. It is not yet known if space and time are used in parallel or sequentially for stimulus selection. To directly compare when temporal and spatial attention affect stimulus processing in the auditory modality, short and long empty intervals (600 and 1,200 ms) were presented. Each interval started with a centrally presented tone (S1) and ended with a second tone (S2) presented either on the left or on the right side. Participants had to attend one point in time (offset of the short or long interval) and one position (left or right side) and had to respond to infrequent, deviant offset markers presented at the attended time point and at the attended position. The N1 of concurrently recorded event-related potentials (ERPs) to the frequent standard stimuli was enhanced by both temporal and spatial attention. The temporal and the spatial N1 attention effect had a similar scalp topography, suggesting common neural generators. By contrast, later effects of temporal and spatial attention, consisting of a posterior positivity and an anterior negativity, markedly differed.