Attention modulates perception of visual space.

Attention readily facilitates the detection and discrimination of objects, but it is not known whether it helps to form the vast volume of visual space that contains the objects and where actions are implemented. Conventional wisdom suggests not, given the effortless ease with which we perceive three-dimensional (3D) scenes on opening our eyes. Here, we show evidence to the contrary. In Experiment 1, the observer judged the location of a briefly presented target, placed either on the textured ground or ceiling surface. Judged location was more accurate for a target on the ground, provided that the ground was visible and that the observer directed attention to the lower visual field, not the upper field. This reveals that attention facilitates space perception with reference to the ground. Experiment 2 showed that judged location of a target in mid-air, with both ground and ceiling surfaces present, was more accurate when the observer directed their attention to the lower visual field; this indicates that the attention effect extends to visual space above the ground. These findings underscore the role of attention in anchoring visual orientation in space, which is arguably a primal event that enhances one's ability to interact with objects and surface layouts within the visual space. The fact that the effect of attention was contingent on the ground being visible suggests that our terrestrial visual system is best served by its ecological niche.