Endogenous spatial attention in far-peripheral vision: Effects of eccentricity and cortical magnification scaling

Endogenous spatial attention allows observers to prioritize behaviorally relevant locations, but whether it remains effective in far-peripheral vision, where the cortical representation of a given stimulus is markedly reduced, is not fully understood. The present study examined whether endogenous spatial attention produces reaction-time facilitation at 40° eccentricity and whether the magnitude of this facilitation varies with eccentricity and stimulus scaling based on cortical magnification. Fifteen participants completed two experiments using a spatial-cuing task in which central arrow cues predicted the side on which targets would appear at 3°, 10°, and 40° eccentricity, with double-headed arrows serving as neutral cues. In Experiment 1, target stimuli were identical in physical size across eccentricities. In Experiment 2, stimulus size was adjusted according to the cortical magnification factor to partially reduce eccentricity-dependent differences in cortical representation. In both experiments, responses were fastest in the valid condition, intermediate in the neutral condition, and slowest in the invalid condition. A reliable cuing effect was observed at 40° eccentricity in both experiments. The magnitude of the cuing effect did not reliably differ across eccentricities in either experiment, nor between the unscaled and M-scaled conditions at 40°. These findings indicate that endogenous spatial attention remains behaviorally effective in far-peripheral vision at 40° eccentricity.