Effect of context and efference copy on visual straight ahead

Vision Res. 1989;29(12):1729-36. doi: 10.1016/0042-6989(89)90155-7.

Abstract

Bias in efferent commands to the eye changes the apparent straight ahead direction in an unstructured visual field, but has little effect in a normal visual environment. Naive subjects set a visible marker to appear straight ahead under monocular viewing conditions and while pressing on the viewing eye. Three background conditions were used: a naturalistic landscape photograph, a blank field, and a repeating checkerboard texture that provides strong contours but no information about visual direction. Effect of eyepress on straight-ahead judgments was small but significant with the landscape background, and larger with the blank field; the checkerboard texture yielded a bias halfway between the magnitudes of bias in the other two conditions. A visual capture theory predicts that the textured field should work like a blank one, while an oculomotor theory predicts that it should work like a natural one. Interpreted in this context, the results show the two theories to be about equally important in judging straight ahead. A second experiment with experienced observers and moving backgrounds gave the same result.

MeSH terms

  • Eye Movements / physiology*
  • Fixation, Ocular / physiology*
  • Humans
  • Vision, Ocular / physiology*
  • Visual Perception / physiology*