A new elementary feature of vision.

Humans can discriminate among elementary features such as orientation, color, and depth in parallel. The author showed that discontinuities in lines, such as a vernier offset, can be detected in a flash presentation with subsequent mask, and an offset, even below the diameter of foveal photoreceptors, is identified among distractors. This result suggests that the visual system simultaneously detects misalignments or gradients of orientation in the hyperacuity range at many positions in the visual field. The direction of the vernier offset, however, cannot be classified simultaneously in several stimuli, but requires serial search.