Orientation Sensitivity
A phenomenon of visual processing in which certain line orientations are more quickly and easily processed and discriminated than other line orientations.
Origin
The earliest known observation dates to 1861, when physicist Ernst Mach found that people made the smallest errors judging horizontal and vertical lines and the largest at 45 degrees. A neural basis emerged when David Hubel and Torsten Wiesel discovered, in 1959, that neurons in the visual cortex fire preferentially for specific orientations — with more cells tuned to cardinal angles than oblique ones. The phenomenon was formally named "the oblique effect" in 1972 by psychologist Stuart Appelle, in a review published in Psychological Bulletin. Hubel and Wiesel received the Nobel Prize in 1981.