The Extrafoveal Preview Effect is More Pronounced Where Perception is Poor

The pre-saccadic preview of a peripheral target enhances the speed and accuracy of its post-saccadic processing, termed the extrafoveal preview effect. Peripheral visual performance –and thus the quality of the preview– varies around the visual field, even at iso-eccentric locations. To investigate whether these polar angle asymmetries influence the preview effect, we asked human participants to preview four tilted Gabors at the cardinals, until a central cue indicated to which to saccade. During the saccade, the target orientation either remained or was flipped (valid/invalid preview). After saccade landing, participants discriminated the orientation of the (briefly presented) second Gabor. Gabor contrast was titrated with adaptive staircases. Valid previews increased participants’ post-saccadic contrast sensitivity. This preview effect was inversely related to polar angle perceptual asymmetries; largest at the upper, and smallest at the horizontal meridian. Our finding reveals that the visual system actively compensates for peripheral asymmetries when integrating information across saccades.Statement of RelevanceEven though visual sensitivity degrades with farther distance from fovea, we make use of peripheral information to monitor or preview the surroundings, for instance, when driving (pedestrians at eye level, instrument panel at the lower visual field, farther things in the upper visual field). When we make saccadic eye movements to foveate relevant items, the peripheral information “previewed” before the saccade supports post-saccadic vision. Because our vision differs around the visual field –at the same eccentricity it is best along the horizontal, worst at the upper vertical meridian– investigating whether peripheral information at different polar angles equally facilitates post-saccadic perception has implications for everyday life. Our study reveals that peripheral preview exerts a larger influence on subsequent foveal processing at locations where vision is worse. This finding suggests that the visual system actively compensates for differences in peripheral vision when integrating information across eye movements.