History Of The Perception Concept Research Paper

1. Perception In Ancient And Medieval Philosophy And Science

Human beings (as other animals) rely on their senses for survival. Although everyone uses the senses, it is not obvious how they work. Initial questions concerned their basic operation and their role in gaining knowledge. In vision, does something go out from the eye to meet the object, or does the object send something to the eye? What do the senses reveal? Do they inform the observer of the very nature of things or are they fundamentally illusory? Or is their function primarily pragmatic?

Aristotle, working in fourth-century (BCE) Athens, wrote the first general treatise on psychology, described as logon peri tes psyches and entitled in Latin translation De anima, ‘on the soul.’ He considered the soul to be the principle of life or vitality, including reproduction and growth, sensory perception and purposeful activity, and intellectual theorizing. He offered a general theory of how the senses work, whereby something travels through a medium to each sense organ: light and color through air in the case of sight, vibrations in the case of sound, odors for smell, and so on. He also held that all knowledge is based on the senses. For ‘proper sensibles’ such as light and color, he postulated that a sample of the quality is received by the sensory soul ‘without the matter’ of the object. His medieval interpreters described this as the reception of a ‘similitude’ of the quality, or a ‘real quality.’ Aristotle held that sensory qualities alone do not reveal the essences of things, which are perceived by a higher cognitive faculty, the intellect, from observing changes over time. He differed from his teacher Plato, who held that in vision something goes from the eye into the air, and who taught that sensory perception is illusory, true knowledge arising from intellectual perception independent of the senses.

In this period ‘optics’ was about vision, not merely the physics of light (Lindberg 1976). In second-century Alexandria, Ptolemy developed a geometrical theory of vision, an extramission theory stating that something goes from eye to object. He modeled the relation between eye and object by a visual pyramid composed of a sheath of rays, with the object serving as base and the apex residing inside the cornea of the eye. The eye senses the direction and length of each ray, thereby perceiving the location of each point in the field of view, and so gaining full knowledge of the shapes, sizes, and places of things.

For centuries no theorist could formulate a mathematically rigorous intromission theory, with causation proceeding from object to eye. If one believes (correctly) that light is scattered from each point of an ordinary object in all directions, a problem arises that extramissionists did not face. It must be explained how the eye senses only one point for each point on the object, despite the fact that each point on the cornea receives light rays from all points in the field of view. Ibn al-Haytham (1030), working in Fatimid Cairo, produced the first accepted solution. He argued that the eye receives only the unrefracted rays (those that meet the cornea at right angles), and hence that it receives a cross-section of the visual pyramid preserving point-for-point the order of the scene. He also elaborated the theory that an object’s true size is perceived through an unnoticed judgment that combines the visual angle under which an object is seen with the perceived distance to the object. This explanation guided psychological theories of size perception for nearly a millennium.

2. Perception In The Modern Age

The Scientific Revolution of the seventeenth century brought changes in perceptual theory. Kepler’s discovery of the retinal image revealed the internal optics of the eye and so produced a new solution to Ibn al-Haytham’s problem, though without altering the latter’s geometrical analysis of size perception or his theory of it, which was further developed by Descartes and Berkeley (Hatfield and Epstein 1979). Descartes postulated physiological systems to produce distance perception directly through the ocular-muscle processes of accommodation and convergence, and Berkeley sought to replace the psychology of unnoticed judgments with associative processes. Aristotle’s theory that samples of qualities are absorbed by the senses was challenged by the new physics, according to which qualities in objects must be reduced to particles having only size, shape, motion, and position (primary qualities). Secondary qualities in objects, such as color, were now to be equated with such particles and their effects on perceivers. Descartes argued that sensory perception does not reveal essences, which are perceived by the intellect independent of the senses. The empiricist Locke denied intellectual perception of that sort, and held that the new physical theories were hypotheses to be tested against sensory observation. Both Descartes and Locke considered experienced qualities such as color to be products of the human sensory system. Contrary to later interpreters (e.g., Burtt 1927), they did not regard them as illusory; if a subjectively produced color sensation is regularly or lawfully caused by qualities in objects, it can be used objectively to sort and classify such objects.

Eighteenth-century European theories of knowledge grappled with the new scientific image of the material world. Berkeley and Hume argued that the new theories devolve into paradox, as when ‘red’ is said both to be an experienced quality and a way light is reflected by surfaces. They sought to avoid skeptical conclusions by reducing knowledge of objects to the merely phenomenal. Reid (see Yolton 1984) countered with a ‘common sense’ affirmation of the reality and knowability of material objects (and of a deity, whose knowability was a primary motivation for him). Kant argued that analysis of the basis of actual knowledge in mathematics and natural science reveals that human knowledge cannot extend beyond sensory experience, so that metaphysical knowledge of God, an immaterial human soul, and the material world as it is in itself is not possible. Hegel countered that Hume, Kant, and others were wrong to think of the world in itself as lying beyond the phenomenally available world. The natures of things are open to human knowledge, but can be grasped only through concepts that develop in a historical process of dialectic.

3. The Nineteenth Century

The nineteenth century was a golden age of sensory physiology and psychology in Germany (Turner 1994). G. Fechner, wanting to measure states of the soul, took psychophysical measurements for pressure on the skin, weights lifted by hand, line lengths perceived by sight, and the pitches of tones. Precise, empirical theories of color and spatial perception were developed by H. Helmholtz and E. Hering. In color theory, Helmholtz postulated three types of light sensitive elements in the eye, with peak sensitivities at different wavelengths. Hering posited opponent-process mechanisms yielding four primary colors, red, green, yellow, and blue, along with a neutral white–black pairing. In spatial perception, Helmholtz argued that all ability for spatial localization is derived from experience, whereas Hering argued that the visual system has innate mechanisms for localizing sensations.

Nearly all major theorists accepted the assumption that perception is based on nonspatial, punctiform sensations varying only in quality and intensity. This assumption was shared by British associationists (e.g., J. Mill and J. vs. Mill), nativists (H. Lotze), and empirists (W. Wundt, Helmholtz). It was questioned by Hering and C. Stumpf in Germany and W. James in the US. Dewey (1896) promulgated a functionalist approach to sensory perception, in which mind functions to adapt organisms to their environments.

4. Twentieth Century Trends

The idea that perception is built up from punctiform sensations was challenged by the Gestalt psychologists. Rather than punctiform sensations or two-dimensional perspective images, the Gestaltists regarded experience of the phenomenally given, meaningful world in three dimensions as the fundamental perceptual state. The American psychologist Gibson (1966) challenged the traditional theory that sensory stimulation provides greatly impoverished information about distant objects. He argued that, in vision, if one grants that organisms move and integrate information over brief intervals of time, then the information available at the eyes specifies fully the spatial layout of the scene. The British psychologist D. Marr developed computational models on the theory that Gibson-like assumptions about objects and stimulation are engineered into sensory systems. I. Rock at Rutgers University espoused the constructivist theory that perception results from inferential processes which combine impoverished sources of stimulation, an approach shared by many information processing and computer vision theorists. Some theorists preferred to view perception as sensory information processing rather than the production of conscious states. New techniques for neurophysiological recording in living animals and brain imaging in humans permitted study of neural activity in perception, though behavioral and phenomenal data guided this research. At the end of the twentieth century all these currents remained visible in perceptual theorizing (Palmer 1999).

Philosophical approaches early in the twentieth century drew inspiration from Hume’s phenomenalism and James’ ‘neutral monism,’ the latter attempting to avoid the mind–body problem by arguing that both the psychological and the physical are composed from neutral existents found in perception. This led to theories of ‘sense data’ that have (in vision) the phenomenal properties of twodimensional perspective projections. Such theories were challenged by critical and representational realism, and their phenomenological claims faded as philosophers took account of the Gestaltists and Gibson (Crane 1992). Philosophical interest in perception shifted from the problem of knowledge (now allotted to the philosophies of the sciences and other cognitive practices) to perception as an instance of the mind–body problem. As the neural correlates of sensory perception became better known, there remained a theoretical gap between neural or informational accounts and the conscious states manifest in perceptual experience. It is not clear how changes in the electrochemical state of neurons in the back of the brain could be the experience of red, despite it being known which neurophysiological patterns yield an experience of red, and which yellow. Much has been learned about how the senses work, but the characteristic feature of perception, conscious awareness, remains unexplained.

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