Fuse left and right images.

Twist – you will see two surfaces with the upper one slanted and the lower one frontal plane.

Hinge – You will see the same two surfaces side by side with the left one slanted and the right one frontal plane.

*The slant is more obvious in the twist configuration, because there is a gradient of discontinuities at the boundary between the two surfaces.

• Gillam, B., Chambers, D., & Russo, T. (1988). Postfusional latency in stereoscopic slant perception and the primitives of stereopsis. Journal of Experimental Psychology: Human Perception and Performance, 14(2), 163-175.
  
  
• Gillam, B., Blackburn, S., & Brooks, K. (2007). Hinge versus twist : The effects of `reference surfaces' and discontinuities on stereoscopic slant perception. Perception, 36, 596-616.