either left or right. To test for cue recruitment, binocular disparity cues (3D cues) were added to the Necker cube, to specify which part of the cube was in front and which was in back. The apparent direction of rotation was thereby brought under experimenter control. The new cue was that the cube moved upward or downward on every trial (contingent on its direction of rotation). Test trials contained the new cue but not the trusted cue. On these trials, trainees tended to see the cube rotating in the same direction it had during training (depending on whether its motion was upward or downward). External links and references Adams, Banks, and van Ee (2001). Adaptation to three-dimensional distortions in human vision. Nature Neuroscience, 4: 1063–1064. Backus (2011). Recruitment of new visual cues for perceptual appearance. Chapter 6 (pp. 101–119) in: Sensory Cue Integration. Edited by Trommershäuser, Körding, and Landy. Oxford University Press. Ernst, Banks, and Bulthoff (2000). Touch can change visual slant perception. Nature Neuroscience, 3: 69–73. Haijiang, Saunders, Stone and Backus (2006). Demonstration of cue recruitment: Change in visual appearance by means of Pavlovian conditioning. Proc. Natl. Acad. Sci. USA, 103: 483–488. Sinha and Poggio (1996). Role of learning in three-dimensional form perception. Nature, 384: 460–463. Learning methods Perception