Visual space perception and visually directed action.

TLDR

The study reports two experiments, one of which examined how subjects matched depth intervals on the ground plane to frontal intervals at the same distance. In the second experiment, participants viewed ground‑plane targets and then, with eyes closed, either walked directly to them or pointed toward them while walking along side paths. Subjects needed larger depth intervals than frontal intervals to perceive equality, with the disparity increasing from 4 m to 12 m, yet their walking and pointing accuracy remained high, indicating that the visual distortion does not affect open‑loop motor tasks.

Abstract

The results of two types of experiments are reported. In 1 type, Ss matched depth intervals on the ground plane that appeared equal to frontal intervals at the same distance. The depth intervals had to be made considerably larger than the frontal intervals to appear equal in length, with this physical inequality of equal-appearing intervals increasing with egocentric distance of the intervals (4 m-12 m). In the other type of experiment, Ss viewed targets lying on the ground plane and then, with eyes closed, attempted either to walk directly to their locations or to point continuously toward them while walking along paths that passed off to the side. Performance was quite accurate in both motoric tasks, indicating that the distortion in the mapping from physical to visual space evident in the visual matching task does not manifest itself in the visually open-loop motoric tasks.