Spatiotemporal mapping of visual attention.
Résumé
The spatial distribution and the temporal dynamics of attention are well understood in isolation, but their interaction remains an open question. How does the shape of the attentional focus evolve over time? To answer this question, we measured spatiotemporal maps of endogenous and exogenous attention in humans (more than 140,000 trials in 23 subjects). We tested the visibility of a low-contrast target presented (50 ms) at different spatial distances and temporal delays from a cue in a noisy background. The cue was a non-informative salient peripheral (5°) stimulus for exogenous attention and a central arrow cue (valid 66.6%) pointing left or right for endogenous attention. As a measure of attention, we determined, for each distance and delay, the background contrast compensation required to keep performance at 75%. The spatiotemporal mapping of exogenous attention revealed a significant enhancement zone from 150 to 430 ms, extending up to 6° from the cue. Endogenous attention maps showed a peak at the cued side at 400 ms and between 8 and 10° from the cue. Modeling suggests that the data are compatible with a constant spotlight shape across time. Our results represent the first detailed spatiotemporal maps of both endogenous and exogenous attention.