ABSTRACT
Beyond the level of simple neural effects, illusions may arise from inappropriate information-processing strategies or cognitive judgmental processes. There is a technique that eliminates the contribution of optical and retinal mechanisms without any change in the nature of the stimulus reaching the higher centers. This technique involves the stereoscopic separation of elements in the illusion configuration. Koehler and Wallach’s theory was probably the first to propose that visual illusions might be the direct result of cortical neural interactions. They offered a mass action theory proposing that there is an isomorphic correspondence between the stimulation on the retina and the cortical response pattern. Some sources of structural interactions in the formation of illusions are more global in nature. For instance, a number of investigators have recently shown that the two cerebral hemispheres are somewhat specialized in terms of their psychological functioning.
