The philosophy of perception concerns how mental processes and symbols depend on the world internal and external to the perceiver.

Introduction

Our perception of the external world begins with the senses, which lead us to generate empirical concepts representing the world around us, within a mental framework relating new concepts to preexisting ones. Because perception leads to an individual's impression of the world, its study may be important for those interested in better understanding communication, self, id, ego — even reality. In psychology and the cognitive sciences, perception is the process of acquiring, interpreting, selecting, and organizing sensory information. ... Senses Senses are a UK based alternative rock band from Coventry. ... Empirical is an adjective often used in conjunction with science, both the natural and social sciences, which means an observation or experiment based upon experience that is capable of being verified or disproved. ... A concept is an abstract, universal psychical entity that serves to designate a category or class of entities, events or relations. ... Look up Communication in Wiktionary, the free dictionary. ... In philosophy, the self is the idea of a unified being which is the source of an idiosyncratic conciousness. ... For other uses of ego and id, see EGO and ID. The id, ego, and super-ego are the divisions of the psyche according to psychoanalyst Sigmund Freuds structural theory. In 1923, Freud introduced new terms to describe the division between the conscious and unconscious: id, ego, and super... Reality in everyday usage means the state of things as they actually exist. ...

While René Descartes concluded that the question "Do I exist?" can only be answered in the affirmative (cogito ergo sum), Freudian psychology suggests that self-perception is an illusion of the ego, and cannot be trusted to decide what is in fact real. Such questions are continuously reanimated, as each generation grapples with the nature of existence from within the human condition. The questions remain: Do our perceptions allow us to experience the world as it "really is?" Can we ever know another point of view in the way we know our own? René Descartes (March 31, 1596 – February 11, 1650), also known as Renatus Cartesius (latinized form), was a highly influential French philosopher, mathematician, scientist, and writer. ... René Descartes (1596–1650) Cogito, ergo sum (Latin: I think, therefore I am) is a philosophical statement used by René Descartes, which became a foundational element of Western philosophy. ... Sigmund Freud His famous couch Sigmund Freud (May 6, 1856 - September 23, 1939) was an Austrian neurologist and the founder of the psychoanalytic school of psychology, a movement that popularized the theory that unconscious motives control much behavior. ... Psychology is an academic or applied discipline involving the scientific study of mental processes such as perception, cognition, emotion, personality, behavior, and interpersonal relationships. ... Reality in everyday usage means the state of things as they actually exist. ... Generation (From the Greek γιγνμαι), also known as procreation, is the act of producing offspring. ... The human condition encompasses the totality of the experience of being human and living human lives. ...

Categories of perception

We can categorize perception as internal or external.

• Internal perception (proprioception) tells us what's going on in our bodies. We can sense where our limbs are, whether we're sitting or standing; we can also sense whether we are hungry, or tired, and so forth.
• External or Sensory perception (exteroception), tells us about the world outside our bodies. Using our senses of sight, hearing, touch, smell, and taste, we discover colors, sounds, textures, etc. of the world at large. There is a growing body of knowledge of the mechanics of sensory processes in cognitive psychology.

The philosophy of perception is mainly concerned with exteroception. When philosophers use the word perception they usually mean exteroception, and the word is used in that sense everywhere. // Proprioception (PRO-pree-o-SEP-shun (IPA pronunciation: ); from Latin proprius, meaning ones own and perception) is the sense of the relative position of neighbouring parts of the body. ... Senses are the physiological methods of perception. ... Cognitive Psychology is the school of psychology that examines internal mental processes such as problem solving, memory, and language. ...

Scientific accounts of perception

The science of perception is concerned with how events are observed and interpreted. An event may be the occurrence of an object at some distance from an observer. According to the scientific account this object will reflect light from the sun in all directions. Some of this reflected light from a particular, unique point on the object will fall all over the corneas of the eyes and the combined cornea/lens system of the eyes will divert the light to two points, one on each retina. The pattern of points of light on each retina forms an image. This process also occurs in the case of silouettes where the pattern of absence of points of light forms an image. The overall effect is to encode position data on a stream of photons and to transfer this encoding onto a pattern on the retinas. The patterns on the retinas are the only optical images found in perception, prior to the retinas light is arranged as a fog of photons going in all directions. A human eye. ... The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber, providing most of an eyes optical power [1]. Together with the lens, the cornea refracts light and, as a result, helps the eye to focus. ... Human eye cross-sectional view. ...

The images on the two retinas are slightly different and the disparity between the electrical outputs from these is resolved either at the level of the lateral geniculate nucleus or in a part of the visual cortex called 'V1'. The resolved data is further processed in the visual cortex where some areas have relatively more specialised functions, for instance area V5 is involved in the modelling of motion and V4 in adding colour. The resulting single image that subjects report as their experience is called a 'percept'. Studies involving rapidly changing scenes show that the percept derives from numerous processes that each involve time delays (see Moutoussis and Zeki (1997)). The lateral geniculate nucleus (LGN) of the thalamus is a part of the brain, which is the primary processor of visual information, received from the retina, in the CNS. Schematic diagram of the primate lateral geniculate nucleus. ... Brodmann area 17 (primary visual cortex) is shown in red in this image which also shows area 18 (orange) and 19 (yellow) The visual cortex refers to the primary visual cortex (also known as striate cortex or V1) and extrastriate visual cortical areas such as V2, V3, V4, and V5. ...

Recent fMRI studies show that dreams, imaginings and perceptions of similar things such as faces are accompanied by activity in many of the same areas of brain. It seems that imagery that originates from the senses and internally generated imagery may have a shared ontology at higher levels of cortical processing. Functional Magnetic Resonance Imaging (or fMRI) describes the use of MRI to measure hemodynamic signals related to neural activity in the brain or spinal cord of humans or other animals. ... In philosophy, ontology (from the Greek , genitive : of being (part. ...

If an object is also a source of sound this is transmitted as pressure waves that are sensed by the cochlear in the ear. If the observer is blindfolded it is difficult to locate the exact source of sound waves, if the blindfold is removed the sound can usually be located at the source. The data from the eyes and the ears is combined to form a 'bound' percept. The problem of how the bound percept is produced is known as the binding problem and is the subject of considerable study. The binding problem is also a question of how different aspects of a single sense (say, color and contour in vision) are bound to the same object when they are processed by spatially different areas of the brain. The binding problem is, basically, the problem of how the unity of conscious perception is brought about by the distributed activities of the central nervous system (Revonsuo and Newman (1999)). In its most general form it arises whenever information from distinct populations of neurons must be combined. ...

Philosophical ideas about perception

The most common theory of perception is naïve realism in which people believe that what they perceive is things in themselves. Children develop this theory as a working hypothesis of how to deal with the world. Many people who have not studied biology carry this theory into adult life and regard their perception to be the world itself rather than a pattern that overlays the form of the world. Thomas Reid took this theory a step further, he realised that sensation was composed of a set of data transfers but declared that these were in some way transparent so that there is a direct connection between perception and the world. This idea is called direct realism and has become popular in recent years with the rise of postmodernism and behaviourism. Direct realism does not clearly specify the nature of the bit of the world that is an object in perception, especially in cases where the object is something like a silhouette. Naive realism is the common sense theory of perception. ... Thomas Reid Thomas Reid (April 26, 1710 – October 7, 1796), Scottish philosopher, and a contemporary of David Hume, was the founder of the Scottish School of Common Sense, and played an integral role in the Scottish Enlightenment. ... Direct realism is a theory of perception that claims that the senses provide us with direct awareness of the external world. ... Postmodernism (sometimes abbreviated as Pomo or PoMo) is a term used in a variety of contexts to describe social conditions, movements in the arts, economic and social conditions and scholarship from the perspective that there is a definable and differentiable period after the modern, or that the 20th century can... Behaviorism (or behaviourism) is an approach to psychology based on the proposition that behavior is interesting and worthy of scientific research. ...

The succession of data transfers that are involved in perception suggests that somewhere in the brain there is a final set of activity, called sense data, that is the substrate of the percept. Perception would then be some form of brain activity and somehow the brain would be able to perceive itself. This concept is known as indirect realism. In indirect realism it is held that we can only be aware of external objects by being aware of representations of objects. This idea was held by John Locke and Immanuel Kant. The common argument against indirect realism, used by Gilbert Ryle amongst others, is that it implies a homunculus or Ryle's regress where it appears as if the mind is seeing the mind in an endless loop. This argument assumes that perception is entirely due to data transfer and classical information processing. This assumption is highly contentious (see strong AI) and the argument can be avoided by proposing that the percept is a phenomenon that does not depend wholly upon the transfer and rearrangement of data. The concept of sense data (singular: sense datum) is very influential and widely used in the philosophy of perception. ... Indirect Realism is the view in cognitive psychology that perception functions via internal representations of external reality. ... This article is about John Locke, the English philosopher. ... Immanuel Kant (22 April 1724 – 12 February 1804), was a German philosopher from Königsberg in East Prussia (now Kaliningrad, Russia). ... Gilbert Ryle (1900–1976), was a philosopher, and a representative of the generation of British ordinary language philosophers influenced by Wittgensteins insights into language, and is principally known for his critique of Cartesian dualism, for which he coined the phrase the ghost in the machine. He referred to some... This article or section is not written in the formal tone expected of an encyclopedia article. ... In philosophy, Ryles regress is a classic argument against cognitivist theories, and concludes that such theories are essentially meaningless as they do not explain what they purport to explain. ... Hondas humanoid robot AI redirects here. ...

Direct realism and indirect realism are known as 'realist' theories of perception because they hold that there is a world external to the mind. Direct realism holds that the representation of an object is located next to, or is even part of, the actual physical object whereas indirect realism holds that the representation of an object is brain activity. Direct realism proposes some as yet unknown direct connection between external representations and the mind whilst indirect realism requires some feature of modern physics to create a phenomenon that avoids infinite regress. Indirect realism is consistent with experiences such as:

binding, dreams, imaginings, hallucinations, illusions, the resolution of binocular rivalry, the resolution of multistable perception, the modelling of motion that allows us to watch TV, the sensations that result from direct brain stimulation, the update of the mental image by saccades of the eyes and the referral of events backwards in time A hallucination is a false sensory perception in the absence of an external stimulus, as distinct from an illusion, which is a misperception of an external stimulus. ... Binocular rivalry is a phenomenon of visual perception in which perception alternates between different images presented to each eye. ... Examples of visually ambiguous patterns. ...

Whereas direct realism argues either that these experiences do not occur or avoids the problem by defining perception as only those experiences that are consistent with direct realism.

Apart from the realist theories of perception there are also anti-realist theories. There are two varieties of anti-realism: Idealism and Skepticism. Idealism holds that we create our reality whereas skepticism holds that reality is always beyond us. One of the most influential proponents of idealism was George Berkeley who maintained that everything was mind or dependent upon mind. Berkeley's idealism has two main strands, phenomenalism in which physical events are viewed as a special kind of mental event and subjective idealism. David Hume is probably the most influential proponent of skepticism. Idealism is an approach to philosophical enquiry that asserts that everything we experience is of a mental nature. ... For the Finnish funeral doom metal band, see Skepticism (band). ... George Berkeley (IPA: ) (12 March 1685 – 14 January 1753), also known as Bishop Berkeley, was an influential Irish philosopher whose primary philosophical achievement is the advancement of a theory dubbed immaterialism by Berkeley himself (also later called subjective idealism). This theory, summed up in his dictum, Esse est percipi (To... In epistemology and the philosophy of perception, phenomenalism is the view that physical objects do not exist as things in themselves but only as perceptual phenomena or sensory stimuli (e. ... Subjective idealism is a theory in the philosophy of perception. ... David Hume (April 26, 1711 – August 25, 1776)[1] was a Scottish philosopher, economist, and historian. ...

The philosophy of perception is very closely related to a branch of philosophy known as epistemology, the theory of knowledge, and many of the ideas presented above are also discussed under this heading. It has been suggested that Meta-epistemology be merged into this article or section. ...

Cognitive processing and epiphenomenalism

Perception is sometimes referred to as a cognitive process in which information processing is used to transfer information from the world into the brain and mind where it is further processed and related to other information. Some philosophers and psychologists propose that this processing gives rise to particular mental states (cognitivism) whilst others envisage a direct path back into the external world in the form of action (radical behaviourism). The term cognition is used in several different loosely related ways. ... In general, information processing is the changing (processing) of information in any manner detectable by an observer. ... The word cognitivism is used in several ways: In ethics, cognitivism is the philosophical view that ethical sentences express propositions, and hence are capable of being true or false. ... Behaviorism (or behaviourism) is an approach to psychology based on the proposition that behavior is interesting and worthy of scientific research. ...

Many eminent behaviourists such as John B. Watson and B.F. Skinner have proposed that perception acts largely as a process between a stimulus and a response but despite this have noted that Ryle's "ghost in the machine" of the brain still seems to exist. As Skinner wrote: John Broadus Watson (January 9, 1878–September 25, 1958) was an American psychologist who established the psychological school of behaviorism, after doing research on animal behavior. ... Burrhus Frederic Skinner (March 20, 1904 _ August 18, 1990) was an American psychologist and author. ...

"The objection to inner states is not that they do not exist, but that they are not relevant in a functional analysis" Skinner 1953.

This view, in which experience is thought to be an incidental by-product of information processing, is known as epiphenomenalism. Epiphenomenalism is a view in philosophy of mind according to which some or all mental states are mere epiphenomena (side-effects or by-products) of physical states of the world. ...

Perceptual space

Another aspect of perception that is common to both realists and anti-realists is the idea of mental or perceptual space. David Hume considers this at some length and concludes that things appear extended because they have the attributes of colour and solidity. A popular modern philosophical view is that the brain cannot contain images so our sense of space must be due to the actual space occupied by physical things. However, as René Descartes noticed, perceptual space has a projective geometry, things within it appear as if they are viewed from a point and are not simply objects arranged in 3D. Mathematicians now know of many types of projective geometry such as complex Minkowski space that might describe the layout of things in perception (see Peters (2000)). It is also known that many parts of the brain contain patterns of electrical activity that correspond closely to the layout of the retinal image (this is known as retinotopy). There are indeed images in the brain but how or whether these become conscious experience is a mystery (see McGinn (1995)). David Hume (April 26, 1711 – August 25, 1776)[1] was a Scottish philosopher, economist, and historian. ... In physics and mathematics, Minkowski space (or Minkowski spacetime) is the mathematical setting in which Einsteins theory of special relativity is most conveniently formulated. ... Retinotopy is the concept that certain areas of the visual cortex are organized in a way that adjacent points in the visual field (that fall on adjacent points on the retina) are processed by neurons in adjacent parts of that cortical area. ...

See also

• Consciousness
• Epistemology
• Psychology
• Perception
• Sensorium
• Visual perception
• Multistable perception
• Cognitive psychology
• Cognitive science
• Transcendental idealism
• George Berkeley
• Thomas Reid
• Immanuel Kant
• Arthur Schopenhauer
• Maurice Merleau-Ponty
• Roderick Chisholm
• Subjective character of experience
• Map-territory relation
• Hallucinations in the sane

Consciousness is a quality of the mind generally regarded to comprise qualities such as subjectivity, self-awareness, sentience, sapience, and the ability to perceive the relationship between oneself and ones environment. ... It has been suggested that Meta-epistemology be merged into this article or section. ... Psychology is an academic or applied discipline involving the scientific study of mental processes such as perception, cognition, emotion, personality, behavior, and interpersonal relationships. ... In psychology and the cognitive sciences, perception is the process of acquiring, interpreting, selecting, and organizing sensory information. ... The term sensorium (plural: sensoria) refers to the sum of an organisms perception, the seat of sensation where it experiences and interprets the environments within which it lives. ... This article or section does not cite its references or sources. ... Examples of visually ambiguous patterns. ... Cognitive Psychology is the school of psychology that examines internal mental processes such as problem solving, memory, and language. ... Cognitive science is usually defined as the scientific study either of mind or of intelligence (e. ... Transcendental idealism is a doctrine founded by 18th-century German philosopher Immanuel Kant. ... George Berkeley (IPA: ) (12 March 1685 – 14 January 1753), also known as Bishop Berkeley, was an influential Irish philosopher whose primary philosophical achievement is the advancement of a theory dubbed immaterialism by Berkeley himself (also later called subjective idealism). This theory, summed up in his dictum, Esse est percipi (To... Thomas Reid Thomas Reid (April 26, 1710 – October 7, 1796), Scottish philosopher, and a contemporary of David Hume, was the founder of the Scottish School of Common Sense, and played an integral role in the Scottish Enlightenment. ... Immanuel Kant (22 April 1724 – 12 February 1804), was a German philosopher from Königsberg in East Prussia (now Kaliningrad, Russia). ... Arthur Schopenhauer (February 22, 1788 – September 21, 1860) was a German philosopher. ... Maurice Merleau-Ponty (March 14, 1908 – May 4, 1961) was a French phenomenologist philosopher, strongly influenced by Edmund Husserl, who is often (some think mistakenly) classified as an existentialist thinker because of his close association with Jean-Paul Sartre and Simone de Beauvoir, and his distinctly Heideggerian conception of Being. ... Roderick M Chisholm (Seekonk, Massachusetts, 1916 -- Providence, Rhode Island, 1999) was an American philosopher, known for his work on epistemology, metaphysics, free will, and the philosophy of perception. ... That all subjective phenomena are associated with a single point of view is called the subjective character of experience. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... An hallucination may occur to a normal person in state of good mental and physical health, even in the apparent absence of a transient trigger factor such as fatigue, intoxication or sensory deprivation. ...

References and further reading

• BonJour, Laurence (2001). "Epistemological Problems of Perception," The Stanford Encyclopedia of Philosophy, Edward Zalta (ed.). Online text
• Burge, Tyler (1991). "Vision and Intentional Content," in E. LePore and R. Van Gulick (eds.) John Searle and his Critics, Oxford: Blackwell.
• Crane, Tim (2005). "The Problem of Perception," The Stanford Encyclopedia of Philosophy, Edward Zalta (ed.). Online text
• Descartes, Rene (1641). Meditations on First Philosophy. Online text
• Dretske, Fred (1981). Knowledge and the Flow of Information, Oxford: Blackwell.
• Evans, Gareth (1982). The Varieties of Reference, Oxford: Clarendon Press.
• Flynn, Bernard (2004). "Maurice Merleau-Ponty," The Stanford Encyclopedia of Philosophy, Edward Zalta (ed.). Online text
• Hume, David (1739-40). A Treatise of Human Nature: Being An Attempt to Introduce the Experimental Method of Reasoning Into Moral Subjects. Online text
• Kant, Immanuel (1781). Critique of Pure Reason. Norman Kemp Smith (trans.) with preface by Howard Caygill, Palgrave Macmillan. Online text
• Lacewing, Michael (unpublished). "Phenomenalism." Online PDF
• Locke, John (1689). An Essay Concerning Human Understanding. Online text
• McCreery, Charles (2006). "Perception and Hallucination: the Case for Continuity." Philosophical Paper No. 2006-1. Oxford: Oxford Forum. Online PDF
• McDowell, John, (1982). "Criteria, Defeasibility, and Knowledge," Proceedings of the British Academy, pp. 455–79.
• McDowell, John, (1994). Mind and World, Cambridge, Mass.: Harvard University Press.
• McGinn, Colin (1995). "Consciousness and Space," In Conscious Experience, Thomas Metzinger (ed.), Imprint Academic. Online text
• Mead, George Herbert (1938). "Mediate Factors in Perception," Essay 8 in The Philosophy of the Act, Charles W. Morris with John M. Brewster, Albert M. Dunham and David Miller (eds.), Chicago: University of Chicago, pp. 125-139. Online text
• Moutoussis, K. and Zeki, S. (1997). "A Direct Demonstration of Perceptual Asynchrony in Vision," Proceedings of the Royal Society of London, Series B: Biological Sciences, 264, pp. 393-399.
• Peacocke, Christopher (1983). Sense and Content, Oxford: Oxford University Press.
• Peters, G. (2000). "Theories of Three-Dimensional Object Perception - A Survey," Recent Research Developments in Pattern Recognition, Transworld Research Network. Online text
• Putnam, Hilary (1999). The Threefold Cord, New York: Columbia University Press.
• Read, Czerne (unpublished). "Dreaming in Color." Online text
• Russell, Bertrand (1912). The Problems of Philosophy, London: Williams and Norgate; New York: Henry Holt and Company. Online text
• Shoemaker, Sydney (1990). "Qualities and Qualia: What's in the Mind?" Philosophy and Phenomenological Research 50, Supplement, pp. 109–31.
• Siegel, Susanna (2005). "The Contents of Perception," The Stanford Encyclopedia of Philosophy, Edward Zalta (ed.). Online text
• Tong, Frank (2003). "Primary Visual Cortex and Visual Awareness," Nature Reviews, Neuroscience, Vol 4, 219. Online text
• Tye, Michael (2000). Consciousness, Color and Content, Cambridge, MA: MIT Press.
• Infoactivity Genesis of perception investigation