Afterimage in the context of "Persistence of vision"

On Vision and Colors (originally translated as On Vision and Colours; German: Ueber das Sehn und die Farben) is a treatise by Arthur Schopenhauer that was published in May 1816 when the author was 28 years old. Schopenhauer had extensive discussions with Johann Wolfgang von Goethe about the poet's Theory of Colours of 1810, in the months around the turn of the years 1813 and 1814, and initially shared Goethe's views. Their growing theoretical disagreements and Schopenhauer's criticisms made Goethe distance himself from his young collaborator. Although Schopenhauer considered his own theory superior, he would still continue to praise Goethe's work as an important introduction to his own.

Schopenhauer tried to demonstrate physiologically that color is "specially modified activity of the retina." The initial basis for Schopenhauer's color theory comes from Goethe's chapter on physiological colors, which discusses three principal pairs of contrasting colors: red/green, orange/blue, and yellow/violet. This is in contrast to the customary emphasis on Newton's seven colors of the Newtonian spectrum. In accordance with Aristotle, Schopenhauer considered that colors arise by the mixture of shadowy, cloudy darkness with light. With white and black at each extreme of the scale, colors are arranged in a series according to the mathematical ratio between the proportions of light and darkness. Schopenhauer agreed with Goethe's claim that the eye tends toward a sum total that consists of a color plus its spectrum or afterimage. Schopenhauer arranged the colors so that the sum of any color and its complementary afterimage always equals unity. The complete activity of the retina produces white. When the activity of the retina is divided, the part of the retinal activity that is inactive and not stimulated into color can be seen as the ghostly complementary afterimage, which he and Goethe call a (physiological) spectrum.

In visual perception, an optical illusion (also called a visual illusion) is an illusion caused by the visual system and characterized by a visual percept that arguably appears to differ from reality. Illusions come in a wide variety; their categorization is difficult because the underlying cause is often not clear but a classification proposed by Richard Gregory is useful as an orientation. According to that, there are three main classes: physical, physiological, and cognitive illusions, and in each class there are four kinds: Ambiguities, distortions, paradoxes, and fictions. A classical example for a physical distortion would be the apparent bending of a stick half immersed in water; an example for a physiological paradox is the motion aftereffect (where, despite movement, position remains unchanged). An example for a physiological fiction is an afterimage. Three typical cognitive distortions are the Ponzo, Poggendorff, and Müller-Lyer illusion. Cognitive visual illusions are the result of unconscious inferences and are perhaps those most widely known.

Pathological visual illusions arise from pathological changes in the physiological visual perception mechanisms causing the aforementioned types of illusions; they are discussed e.g. under visual hallucinations.

Iconic memory is the visual sensory memory register pertaining to the visual domain and a fast-decaying store of visual information. It is a component of the visual memory system which also includes visual short-term memory (VSTM) and long-term memory (LTM). Iconic memory is described as a very brief (<1 second), pre-categorical, high capacity memory store. It contributes to VSTM by providing a coherent representation of our entire visual perception for a very brief period of time. Iconic memory assists in accounting for phenomena such as change blindness and continuity of experience during saccades. Iconic memory is no longer thought of as a single entity but instead, is composed of at least two distinctive components. Classic experiments including Sperling's partial report paradigm as well as modern techniques continue to provide insight into the nature of this SM store.

"Persistence of vision" is the more general (and often outdated) notion of lingering visual impressions (potentially including afterimages and palinopsia), commonly associated with the reason why the interruptions between images in film and other stroboscopic media go unnoticed.