ABSTRACT
The Greek writers and philosophers wrote about the problems of perception at great length. In general, they seemed to espouse one of two viewpoints: sensory inputs are variable and inaccurate; and senses are inherently accurate. From the first point of view, perceptual errors arise when the senses are relied on more than the mind, whereas from the second point of view, perceptual errors arise when the mind interferes with the work of the senses. In his emphasis on visual information processing strategies, Helmholtz offered a theory of perception. He proposed that, in general, perception in the adult observer is based on unconscious inferences that the mind makes about the pattern of excitation in the nervous system. Since analytic introspection failed to eliminate visual illusions, even in trained observers, Wundt suggested that the final conscious percept might be a “creative synthesis” between sensory and nonsensory elements. The years between 1915 and 1950 were relatively inactive ones for research in visual illusions.
