The Z Lens is a sophisticated piece of apparatus developed by Roger Sperry and his associates in 1955 to enable them to project visual stimuli onto the retina of the eye so that they are interpreted either by the left or right hemisphere of the brain, not both at once. Sperry, a pioneer of the split brain operation, used it to demonstrate that split brain patients had two separate visual inner worlds. If the picture of an object was presented to the left hemisphere, the patient recognized it when it was presented again to the same hemisphere. However, if the same object was presented to the other half of the visual field, the patient had no recollection of having seen it before.
Kristal, L. ed. (1981). ABC of Psychology. London: Multimedia Publications Inc.
Contributed by: L.A. Keple, December 1, 1995