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Perception
- 1. Perception
- 6. Naïve realism The world is pretty much as common sense would have it. All objects are composed of matter, they occupy space, and have properties such as size, shape, texture, smell, taste and color. These properties are usually perceived correctly. So, when we look at and touch things we see and feel those things directly, and so perceive them as they really are. Objects continue to obey the laws of physics and retain all their properties whether or not there is anyone present to observe them doing so
- 7. Theory of naïve realism There exists a world of material objects. Statements about these objects can be known to be true through sense-experience. These objects exist not only when they are being perceived but also when they are not perceived. The objects of perception are largely perception-independent. These objects are also able to retain properties of the types we perceive them as having, even when they are not being perceived. Their properties are perception-independent.
- 8. Naïve realism Naïve realism proposes no physical theory of experience and does not identify experience with the experience of quantum phenomena or with the twin retinal images. This lack of supervenience of experience on the physical world means that naïve realism is not a physical theory
- 9. Scientific realism The universe really contains just those properties which feature in a scientific description of it, and so does not contain properties like colour per se, but merely objects that reflect certain wavelengths owing to their microscopic surface texture. The world only contains the primary qualities that feature in a corpuscularian scientific account of the world Other properties were entirely subjective, depending for their existence upon some perceiver who can observe the objects. (John Locke)
- 10. Epistemological Dualism Whether the world we see around us is the real world itself, or merely an internal perceptual copy of that world generated by neural processes in our brain Representative realism claims that we are directly aware only of internal representations of the external world, as objects are hidden behind a "veil of perception". Idealism asserts that no world exists apart from mind-dependent ideas.
- 17. Externalism and Internalism 6/7/2010 17 Epistemology an Introduction
- 18. How we can gain knowledge via perception?
- 19. Weber’s Law
- 23. Origin of Gestalt Psychology
- 24. Theoretical framework and methodology
- 25. emergence
- 26. Reification is
- 27. Multistability
- 28. Invariance
- 29. Prägnanz
- 31. Application
- 32. Minds Eye
- 33. Visual Thinking
- 34. Is the glass half empty or half full?
- 35. Ambiguous image
- 36. Alice in Wonderland syndrome
Notas del editor
- In philosophy, psychology, and cognitive science, perception is the process of attaining awareness or understanding of sensory information. The word "perception" comes from the Latin words perceptio, percipio, and means "receiving, collecting, action of taking possession, apprehension with the mind or senses. (Oxford English Dictionary)
- Two types of consciousness are considerable regarding perception: phenomenal (any occurrence that is observable and physical) and psychological. The difference everybody can demonstrate to him- or herself is by the simple opening and closing of his or her eyes: phenomenal consciousness is thought, on average, to be predominately absent without sight. Through the full or rich sensations present in sight, nothing by comparison is present while the eyes are closed. Using this precept, it is understood that, in the vast majority of cases, logical solutions are reached through simple human sensation.
- Passive perception (conceived by René Descartes) can be surmised as the following sequence of events: surrounding -> input (senses) -> processing (brain) -> output (re-action). Although still supported by mainstream philosophers, psychologists and neurologists, this theory is nowadays losing momentum. The theory of active perception has emerged from extensive research of sensory illusions, most notably the works ofRichard L. Gregory. This theory, which is increasingly gaining experimental support, can be surmised as dynamic relationship between "description" (in the brain) ↔ senses ↔ surrounding, all of which holds true to the linear concept of experience
- The philosophy of perception is concerned with the nature of sensory and perceptual experience, the status of what is given in such experience, and in particular with how beliefs or knowledge about the (physical) world can be accounted for and justified on that basis.
- A central question to the philosophy of perception concerns what constitutes the immediate objects of perception. Contrary to the position of naïve realism—which can be identified with the 'everyday' impression of physical objects constituting what is perceived—certain observations are put forward which suggest otherwise. The latter comprise perceptual illusions, hallucinations, and the relativity of perceptual experience, but also insights from the field of science.Naïve realism also known as direct realism or common sense realism, is a common sense theory ofperception."Naïve realism claims that the world is pretty much as common sense would have it. All objects are composed of matter, they occupy space, and have properties such as size, shape, texture, smell, taste and colour. These properties are usually perceived correctly. So, when we look at and touch things we see and feel those things directly, and so perceive them as they really are. Objects continue to obey the laws of physics and retain all their properties whether or not there is anyone present to observe them doing so."[1]
- Theory of naïve realismThe naïve realist theory may be characterized as the acceptance of the following 5 beliefs:There exists a world of material objects.Statements about these objects can be known to be true through sense-experience.These objects exist not only when they are being perceived but also when they are not perceived. The objects of perception are largely perception-independent.These objects are also able to retain properties of the types we perceive them as having, even when they are not being perceived. Their properties are perception-independent.By means of our senses, we perceive the world directly, and pretty much as it is. In the main, our claims to have knowledge of it are justified."[3]"Naïve realism is distinct from scientific realism. "[1]
- In contrast, indirect or representative realism claims that we are directly aware only of internal representations of the external world, as objects are hidden behind a "veil of perception". Idealism, on the other hand, asserts that no world exists apart from mind-dependent ideas.Naïve realism proposes no physical theory of experience and does not identify experience with the experience of quantum phenomena or with the twin retinal images. This lack of supervenience of experience on the physical world means that naïve realism is not a physical theory.[2]
- Scientific realism states The universe really contains just those properties which feature in a scientificdescription of it, and so does not contain properties like colour per se, but merely objects that reflect certain wavelengths owing to their microscopic surface texture. The naïve realist, on the other hand, would say that objects really do possess the colours we perceive them to have. An example of a scientific realist is John Locke, who held the world only contains the primary qualities that feature in a corpuscularian scientific account of the world (see corpuscular theory), and that other properties were entirely subjective, depending for their existence upon some perceiver who can observe the objects.
- "The debate over the nature of conscious experience is confounded by the deeper epistemological question of whether the world we see around us is the real world itself, or merely an internal perceptual copy of that world generated by neural processes in our brain. In other words this is the question of direct realism, also known as naïve realism, as opposed to indirect realism, or representationalism."[4]In contrast, "Representationalism is the philosophical position that the world we see in conscious experience is not the real world itself, but merely a miniature virtual-reality replica of that world in an internal representation. Representationalism is also known (in psychology) as Indirect Perception, and (in philosophy) as Indirect Realism, or Epistemological Dualism."[5]"Of all the branches of human knowledge, philosophy might be expected to be the best inoculated against the naïve realist error, since the issue of the epistemology of conscious experience is a central focus of philosophy. However, modern philosophy is just as rife with naïve realists as are modern psychology and neuroscience. As in psychology there is a recurring pattern of the occasional visionary who points out the fallacy of the naïve view, interspersed with long periods of enthusiastic support for the latest naïve inspired view, although again the issue is generally not addressed directly but only peripherally, as it is hidden in the details of various theories." [6][edit]Arguments for and against naïve realism"Although this issue is not much discussed in contemporary psychology, it is an old debate that has resurfaced several times, but the continued failure to reach consensus on this issue continues to bedevil the debate on the functional role of conscious experience. The reason for the continued confusion is that both direct and indirect realism are frankly incredible, although each is incredible for different reasons."[4]
- [edit]Problems with naïve realism"The direct realist view (Gibson, 1972) is incredible because it suggests that we can have experience of objects out in the world directly, beyond the sensory surface, as if bypassing the chain of sensory processing. For example if light from [your computer screen] is transduced by your retina into a neural signal which is transmitted from your eye to your brain, then the very first aspect of the [computer screen] that you can possibly experience is the information at the retinal surface, or the perceptual representation that it stimulates in your brain. The physical [screen] itself lies beyond the sensory surface and therefore must be beyond your direct experience. But the perceptual experience of the [screen] stubbornly appears out in the world itself instead of in your brain, in apparent violation of everything we know about the causal chain of vision. The difficulty with the concept of direct perception is most clearly seen when considering how an artificial vision system could be endowed with such external perception. Although a sensor may record an external quantity in an internal register or variable in a computer, from the internal perspective of the software running on that computer, only the internal value of that variable can be "seen", or can possibly influence the operation of that software. In exactly analogous manner the pattern of electrochemical activity that corresponds to our conscious experience can take a form that reflects the properties of external objects, but our consciousness is necessarily confined to the experience of those internal effigies of external objects, rather than of external objects themselves. Unless the principle of direct perception can be demonstrated in a simple artificial sensory system, this explanation remains as mysterious as the property of consciousness it is supposed to explain."[4][
- edit]Problems with representative realism"The indirect realist view is also incredible, for it suggests that the solid stable structure of the world that we perceive to surround us is merely a pattern of energy in the physical brain. In other words, the world that appears to be external to our head is actually inside our head. This could only mean that the head we have come to know as our own is not our true physical head, but is merely a miniature perceptual copy of our head inside a perceptual copy of the world, all of which is completely contained within our true physical skull. Stated from the internal phenomenal perspective, out beyond the farthest things you can perceive in all directions, i.e. above the dome of the sky and below the earth under your feet, or beyond the walls, floor, and ceiling of the room you perceive around you, beyond those perceived surfaces is the inner surface of your true physical skull encompassing all that you perceive, and beyond that skull is an unimaginably immense external world, of which the world you see around you is merely a miniature virtual reality replica. The external world and its phenomenal replica cannot be spatially superimposed, for one is inside your physical head, and the other is outside. Therefore the vivid spatial structure of this page that you perceive here in your hands is itself a pattern of activation within your physical brain, and the real paper of which it is a copy is out beyond your direct experience. Although this statement can only be true in a topological, rather than a strict topographical sense, this insight emphasizes the indisputable fact that no aspect of the external world can possibly appear in consciousness except by being represented explicitly in the brain. The existential vertigo occasioned by this concept of perception is so disorienting that only a handful of researchers have seriously entertained this notion or pursued its implications to its logical conclusion. (Kant 1781/1991, Koffka 1935, Köhler 1971 p. 125, Russell 1927 pp 137-143, Smythies 1989, 1994, Harrison 1989, Hoffman 1998)"[4]"The key to this problem of fitting a spacious world into our brains is to notice that our experience is a 'view' of a spacious world. Things are separated by angles relative to an observation point. The separation of things by angles at a point means that we do not have a sense of depth that operates in the same way as our sense of things being separated in horizontal and vertical directions. Our sense of depth is based upon cues rather than an actual experience of the space between things. As an example, the stars in a planetarium appear incredibly distant even though they are on the ceiling of a room and would appear just as distant if viewed through virtual reality goggles. Visual depth in particular is a set of inferences, not an actual experience of the space between things in a radial direction outward from the observation point. This means that the things that are the spacious world of experience could be as small as just a few cubic millimetres of brain tissue!"[7]"If there is anything to be learned from the long history of the epistemological debate, it is that the issue is by no means simple or trivial, and that whatever is ultimately determined to be the truth of epistemology, we can be sure that it will do considerable violence to our common-sense view of things. This however is nothing new in science, for many of the greatest discoveries of science seemed initially to be so incredible that it took decades or even centuries before they were generally accepted. But accepted they were, eventually, and the reason why they were accepted was not because they had become any less incredible. In science, irrefutable evidence triumphs over incredibility, and this is exactly what gives science the power to discover unexpected or incredible truth."[6][
- edit]The Argument from IllusionIllusion creates a problem for naïve realists as it suggests our senses are fallible, perceiving things that aren't there. In this illusion, the lines are horizontal, despite how they appear.This argument was "first offered in a more or less fully explicit form in Berkeley (1713)."[8] It is also referred to as the problem of conflicting appearances (e.g. Myles Burnyeat's article Conflicting Appearances). The basic outline of the argument goes as follows:"[W]e should remember that the following considerations are also part of informed commonsense.A. What we perceive is often dependent on our organs of perception and their condition. If we had compound eyes, as flies do, we would receive information about the visual world in a completely different form. If we had jaundice, things would look yellow. If we had other sense organs altogether, like infra-red detectors or echo-location devices, things might appear to us in ways which we can’t even imagine. (Let’s call this ‘perceptual variability’).B. Even our current perceptual apparatus is obviously not infallible. We are all familiar with perceptual illusions of various sorts. A major sub-classification of such illusions relates to whether the sensory organs are malfunctioning (as in jaundice) or whether they habitually misrepresent objects to us even in full working order (e.g. the Müller-Lyer illusion).C. Sometimes these perceptual illusions extend to cases where we think we perceive things which in fact aren’t there at all (rather than just misperceiving the properties of things which are there to be perceived). This is a more radical case of perceptual error than simple illusion. (Call it ‘hallucination’ or ‘perceptual delusion’)."[3]Illusions are present in nature. Rainbows are an example of a perceptual delusion. "For, unlike an architectural arch, a rainbow recedes as we approach it, never to be reached."[9]"The basic claim is that in cases of illusion or hallucination, the object that is immediately experienced or given has qualities that no public physical object in that situation has and so must be distinct from any such object. And in cases of perceptual relativity, since objects with different qualities are experienced from each of the different perspectives or under each of the relevant conditions, at most one of these various immediately experienced or given objects could be the physical object itself; it is then further argued that since there is no apparent experiential basis for regarding one out of any such set of related perceptual experiences as the one in which the relevant physical object is itself immediately experienced, the most reasonable conclusion is that the immediately experienced or given object is always distinct from the physical object. (Or, significantly more weakly, that there is no way to identify which, if any, of the immediately experienced objects is the physical object itself, so that the evidential force of the experience is in this respect the same in all cases, and it is epistemologically as though physical objects were never given, whether or not that is in fact the case.)"[8]"The naïve realist theory of perception is not threatened by these facts [A,B & C] as they stand, for they are accommodated by that theory by virtue its very vagueness (or ‘open-texture’). The theory just isn’t specific or detailed enough to be refuted by the (actually very rare) occurrence of these cases."[3]"The cogency of this argument has been challenged in a number of different ways, of which the most important are the following. First, it has been questioned whether there is any reason to suppose that in cases of these kinds there must be some object present that actually has the experienced qualities, which would then seemingly have to be something like a sense-datum. Why couldn't it be that the perceiver is simply in a state of seeming to experience such an object without any object actually being present? (See the discussion below of the adverbial theory.) Second, it has been argued that in cases of illusion and perceptual relativity at least, there is after all an object present, namely the relevant physical object, which is simply misperceived, for the most part in readily explainable ways. Why, it is asked, is there any need to suppose that an additional object is also involved? Third, the last part of the perceptual relativity version of the argument has been challenged, both (i) by questioning whether it is really true that there is no experiential difference between veridical and non-veridical perception; and (ii) by arguing that even if sense-data are experienced in non-veridical cases and even if the difference between veridical and non-veridical cases is, as claimed, experientially indiscernible, there is still no reason to think that sense-data are the immediate objects of experience in veridical cases. Fourth, various puzzling questions have been raised about the nature of sense-data: Do they exist through time or are they momentary? Can they exist when not being perceived? Are they public or private? Can they be themselves misperceived? Do they exist in minds or are they extra-mental, even if not physical? On the basis of the intractability of these questions, it has been argued that the conclusion of the argument from illusion is clearly unacceptable or even ultimately unintelligible, even in the absence of a clear diagnosis of exactly where and how it goes wrong."[8][
- edit]The argument from the scientific account of perception"The main aspects of that account that are cited in this connection are: (i) the fact that the character of the resulting experience and of the physical object that it seems to present can be altered in major ways by changes in the conditions of perception or the condition of the relevant sense-organs and the resulting neurophysiological processes, with no change in the external physical object (if any) that initiates this process and that may seem to be depicted by the experience that results; (ii) the related fact that any process that terminates with the same sensory and neural results will yield the same perceptual experience, no matter what the physical object (if any) that initiated the process may have been like; and (iii) the fact that the causal process that intervenes between the external object and the perceptual experience takes at least a small amount of time, so that the character of the experience reflects (at most) an earlier stage of that object rather than the one actually existing at that moment. In extreme cases, as in observations of astronomical objects, the external object may have ceased to exist long before the experience occurs. These facts are claimed to point inexorably to the conclusion that the direct or immediate object of such an experience, the object that is given, is an entity produced at the end of this causal process and is thus distinct from the physical object, if any, that initiates the process."[8][
- edit]The Adverbial Theory of naïve realismIn the above argument from the scientific account of perception, "[i]t is difficult to resist the conclusion that there is a fundamental distinction between the external object, if any, that initiates the perceptual process and the perceptual experience that eventually results. This perceptual dualism thus raises inevitably the issue of how and even whether the object can be known on the basis of the experience. What can and has been resisted, by the adverbial theory in particular, is the idea that this dualism is a dualism of objects, with perceptual experience being a more direct experience of objects of a different sort, sense-data."[8]Perceptual dualism implies, "both an act of awareness (or apprehension) and an object (the sense-datum) which that act apprehends or is an awareness of. The fundamental idea of the adverbial theory, in contrast, is that there is no need for such objects and the problems that they bring with them (such as whether they are physical or mental or somehow neither). Instead, it is suggested, merely the occurrence of a mental act or mental state with its own intrinsic character is enough to account for the character of immediate experience."[8]"According to the adverbial theory, what happens when, for example, I immediately experience a silver elliptical shape (as when viewing a coin from an angle) is that I am in a certain specific state of sensing or sensory awareness or of being appeared to: I sense in a certain manner or am appeared to in a certain way, and it is that specific manner of sensing or way of being appeared to that accounts for the specific content of my immediate experience... The essential point here is that when I sense or am appeared to silver-elliptical-ly, there need be nothing more going on than that I am in a certain distinctive sort of experiential state. In particular, there need be no object or entity of any sort that is literally silver and elliptical — not in the material world, not in my mind, and not even in the realm (if there is such a realm) of things that are neither physical nor mental."[8][
- edit]Sense-datum and adverbial theories"The sense-datum theory accounts more straightforwardly for the character of immediate experience. I experience a silver and elliptical shape because an object or entity that literally has that color and shape is directly before my mind. But both the nature of these entities and (as we will see further below) the way in which they are related to the mind are difficult to understand."[8]"The adverbial theory, on the other hand, has the advantage of being metaphysically simpler and of avoiding difficult issues about the nature of sense-data. The problem with it is that we seem to have no real understanding of the nature of the states in question or of how exactly they account for the character of immediate experience."[8][edit]Quantum physics and naïve realism"Scientific realism in classical (i.e. pre-quantum) physics has remained compatible with the naïve realism of everyday thinking on the whole; whereas it has proven impossible to find any consistent way to visualize the world underlying quantum theory in terms of our pictures in the everyday world. The general conclusion is that in quantum theory naïve realism, although necessary at the level of observations, fails at the microscopic level."[10]Experiments such as the Stern–Gerlach experiment and quantum phenomena such as complementarity lead quantum physicists to conclude that "[w]e have no satisfactory reason for ascribing objective existence to physical quantities as distinguished from the numbers obtained when we make the measurements which we correlate with them. There is no real reason for supposing that a particle has at every moment a definite, but unknown, position which may be revealed by a measurement of the right kind... On the contrary, we get into a maze of contradiction as soon as we inject into quantum mechanics such concepts as carried over from the language and philosophy of our ancestors... It would be more exact if we spoke of 'making measurements' of this, that, or the other type instead of saying that we measure this, that, or the other 'physical quantity'."[11]" "[W]e have to give up the idea of realism to a far greater extent than most physicists believe today." (Anton Zeilinger)... By realism, he means the idea that objects have specific features and properties — that a ball is red, that a book contains the works of Shakespeare, or that an electron has a particular spin... for objects governed by the laws of quantum mechanics, like photons and electrons, it may make no sense to think of them as having well defined characteristics. Instead, what we see may depend on how we look."[12]These conclusions do not only apply to microscopic systems such as particles and atoms. "Quantum mechanics is increasingly applied to larger and larger objects. Even a one-ton bar proposed to detect gravity waves must be analysed quantum mechanically. In cosmology, a wavefunction for the whole universe is written to study the Big Bang. It gets harder today to nonchalantly accept the realm in which the quantum rules apply as somehow not being physically real, 'Quantum mechanics forces us to abandon naïve realism'."[13][edit]Virtual reality and naïve realism"Virtual realism"[14] is closely related to the above theories.In the research paper The reality of virtual reality it is proposed that, "virtuality is itself a bonafide mode of reality, and that 'virtual reality' must be understood as 'things, agents and events that exist in cyberspace'. These proposals resolve the incoherences found in the ordinary uses of these terms... 'virtual reality', though based on recent information technology, does not refer to mere technological equipment or purely mental entities, or to some fake environment as opposed to the real world, but that it is an ontological mode of existence which leads to an expansion of our ordinary world."[15]"The emergence of teleoperation and virtual environments has greatly increased interest in "synthetic experience", a mode of experience made possible by both these newer technologies and earlier ones, such as telecommunication and sensory prosthetics... understanding synthetic experience must begin by recognizing the fallacy of naïve realism and with the recognition that the phenomenology of synthetic experience is continuous with that of ordinary experience."[16]
- Externalism and internalismMain article: Internalism and externalismPart of the debate over the nature of knowledge is a debate between epistemological externalists on the one hand, and epistemological internalists on the other. Externalists think that factors deemed "external", meaning outside of the psychological states of those who gain knowledge, can be conditions of knowledge. For example, an externalist response to the Gettier problem is to say that, in order for a justified true belief to count as knowledge, it must be caused, in the right sort of way, by relevant facts. Such causation, to the extent that it is "outside" the mind, would count as an external, knowledge-yielding condition. Internalists, contrariwise, claim that all knowledge-yielding conditions are within the psychological states of those who gain knowledge.René Descartes, prominent philosopher and supporter of internalism wrote that, since the only method by which we perceive the external world is through our senses, and that, since the senses are not infallible, we should not consider our concept of knowledge to be infallible. The only way to find anything that could be described as "infallibly true," he advocates, would be to pretend that an omnipotent, deceitful being is tampering with one's perception of the universe, and that the logical thing to do is to question anything that involves the senses. "Cogito ergo sum" (I think, therefore I am) is commonly associated with Descartes' theory, because he postulated that the only thing that he could not logically bring himself to doubt is his own existence: "I do not exist" is a contradiction in terms; the act of saying that one does not exist assumes that someone must be making the statement in the first place. Though Descartes could doubt his senses, his body and the world around him, he could not deny his own existence, because he was able to doubt and must exist in order to do so. Even if some "evil genius" were to be deceiving him, he would have to exist in order to be deceived. However from this Descartes did not go as far as to define what he was. This was pointed out by the materialist philosopher Pierre Gassendi (1592–1655) who accused Descartes of saying that he was "not this and not that," while never saying what exactly was existing. One could argue that this is not an edifying question, because it doesn't matter what exactly exists, it only matters that it does indeed exist.
- Depending on the kind of immediate objects and mechanism admitted to account for questions concerning perception, several internalist positions can be distinguished. Realistconceptions comprise phenomenalism, representationalism (also called representative or indirect realism) and direct realism (which has certain similarities with naïve realism, yet constitutes a thorough philosophical conception and must therefore be treated separately). Anti-realist conceptions, on the other hand, comprise idealism and skepticism.Historically, the most important philosophical problems posed by perception concerned the epistemology of perception--the question of how we can gain knowledge via perception. However, the problems raised by perception also touch on other fields of philosophy--the nature of qualia is an important topic in the philosophy of mind[1] Moreover, any fully explicit account of perception requires a commitment to one of a variety of ontological (metaphysical) viewpoints on a spectrum of direct realism, indirect realism, and idealism.The most common belief about perception, probably universal in childhood, is naïve realism, in which people believe that what they perceive are things in themselves. Many people who have not studied biology carry this belief into adult life. In this form, naive realism is not strictly a theory but rather an axiom on which all thought and use of language is based. In a sense it is transparently true. If I see a chair it is a chair that I see. When biologists say that this is mistaken, there has been a subtle change in the meaning of the word see (or perceive) that is necessary for a scientific account of how the brain works but unfortunately is not made clear by new terminology. Cross purpose arguments can result. That childhood naive realism is indeed a belief that amounts to an implicit theory is shown by the common humbling experience of arguing its validity as a first year biology student only to be forced to admit that one's position is self-contradictory even without the results of experiments on perception that demonstrate its absurdity. Within the biological study of perception naive realism is unusable[2]. However, outside biology modified forms of naive realism are defended. Thomas Reid in the eighteenth century 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. 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.The succession of data transfers that are involved in perception suggests that somewhere in the brain there is a final set of events, in which sense data are somehow available to a perceiving subject, that is the substrate of the percept. Perception would then be some form of brain activity and somehow some part of the brain would be able to perceive signals provided by some other (or the same??) part of the brain. This concept is known as indirect realism or representative 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 Nicolas Malebranche. The common argument against indirect realism is that it implies a homunculus with an infinite regress (a perceiver within a perceiver within a perceiver...). However, as long as each stage of sensory processing achieves a different task a finite regress is perfectly possible [3]. The above argument against indirect realism has also been challenged on the grounds that it assumes that perception is entirely due to data transfer and classical information processing (see strong AI). It is suggested that 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 real problem here probably relates not so much to issues of infinite regress as to basic ontological issues of the sort raised by Leibniz [4] Locke,Hume, Whitehead and others, which fall beyond the scope of this account.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 the resolution of ontological issues relating to fundamental physics which remain outstanding, particularly in relation to the binding problem. Indirect realism provides an account of issues such as:qualia, 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 timewhereas direct realism has to argue 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 reality is limited to mental qualities, while skepticism challenges our ability to gain knowledge of any reality external to our mind. One of the most influential proponents of idealism was George Berkeleywho 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.A third theory of perception attempts to find a middle path between realist and anti-realist theories. Called enactivism, the theory posits that reality arises as a result of the dynamic interplay between an organism's sensorimotor capabilities and its environment. Instead of seeing perception as a passive process determined entirely by the features of an independently existing world, enactivism suggests that organism and environment are structurally coupled and codetermining. The theory was first formalized by Francisco Varela, Evan Thompson, and Eleanor Rosch in "The Embodied Mind" [5].[edit]Scientific accounts of perceptionThe 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 eyesand 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.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 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)).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.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.[edit]Categories of perceptionWe 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.[edit]Cognitive processing and epiphenomenalismPerception 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).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:"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.[edit]Perceptual spaceAnother 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)).
- The Weber–Fechner law attempts to describe the relationship between the physical magnitudes of stimuli and the perceived intensity of the stimuli. Ernst Heinrich Weber (1795–1878) was one of the first people to approach the study of the human response to a physical stimulus in aquantitative fashion. Gustav Theodor Fechner (1801–1887) later offered an elaborate theoretical interpretation of Weber's findings, which he called simply Weber's law.The case of weightIn one of his experiments, Weber gradually increased the weight that a blindfolded man was holding and asked him to respond when he first felt the increase. Weber found that the smallest noticeable difference in weight (the least difference that the test person can still perceive as a difference), was proportional to the starting value of the weight. That is to say, if the weight is 1 kg, an increase of a few grams will not be noticed. Rather, when the mass is increased by a certain factor, an increase in weight is perceived. If the mass is doubled, the threshold called smallest noticeable difference also doubles. This kind of relationship can be described by a differential equation as,where dp is the differential change in perception, dS is the differential increase in the stimulus andS is the stimulus at the instant. A constant factor k is to be determined experimentally.Integrating the above equation giveswhere C is the constant of integration, ln is the natural logarithm.To determine C, put p = 0, i.e. no perception; then subtract − klnS0 from both sides and rearrange:where S0 is that threshold of stimulus below which it is not perceived at all.Substituting this value in for C above and rearranging, our equation becomes:The relationship between stimulus and perception is logarithmic. This logarithmic relationship means that if a stimulus varies as a geometric progression (i.e. multiplied by a fixed factor), the corresponding perception is altered in an arithmetic progression (i.e. in additive constant amounts). For example, if a stimulus is tripled in strength (i.e, 3 x 1), the corresponding perception may be two times as strong as its original value (i.e., 1 + 1). If the stimulus is again tripled in strength (i.e., 3 x 3 x 1), the corresponding perception will be three times as strong as its original value (i.e., 1 + 1 + 1). Hence, for multiplications in stimulus strength, the strength of perception only adds.This logarithmic relationship is valid, not just for the sensation of weight, but for other stimuli and our sensory perceptions as well.In addition, the mathematical derivations of the torques on a simple beam balance produce a description that is strictly compatible with Weber's law (see link1 or link2).[edit]The case of visionThe eye senses brightness approximately logarithmically over a fairly broad range. Hence stellar magnitude is measured on a logarithmic scale. This magnitude scale was invented by the ancient Greek astronomer Hipparchus in about 150 B.C. He ranked the stars he could see in terms of their brightness, with 1 representing the brightest down to 6 representing the faintest, though now the scale has been extended beyond these limits. An increase in 5 magnitudes corresponds to a decrease in brightness by a factor of 100. Modern researchers have attempted to incorporate such perceptual effects into mathematical models of vision.[1][2][edit]The case of soundStill another logarithmic scale is the decibel scale of sound intensity. And yet another is pitch, which, however, differs from the other cases in that the physical quantity involved is not a "strength".In the case of perception of pitch, humans hear pitch in a logarithmic or geometric ratio-based fashion: For notes spaced equally apart to the human ear, the frequencies are related by a multiplicative factor. For instance, the frequency of corresponding notes of adjacent octaves differ by a factor of 2. Similarly, the perceived difference in pitch between 100 Hz and 150 Hz is the same as between 1000 Hz and 1500 Hz. Musical scales are always based on geometric relationships for this reason. Notation and theory about music often refers to pitch intervals in an additive way, which makes sense if one considers the logarithms of the frequencies, asLoudness: Weber's law does not quite hold for loudness. It is a good approximation for higher amplitudes, but not for lower amplitudes.Tempo: The Weber-Fechner law does hold for musical tempo (the difference between a tempo of 60 beats per minute and 61 bpm is perceived as a much larger difference than between 200bpm and 201bpm) [3][edit]The case of numerical cognitionPsychological studies show that numbers are thought of as existing along a mental number line.[4]Larger entries are on the right and smaller entries on the left. It becomes increasingly difficult to discriminate among two places on a number line as the distance between the two places decreases—known as the distance effect.[5] This is important in areas of magnitude estimation, such as dealing with large scales and estimating distances. See this article [2] on logarithmic number representation.
- In the case of visual perception, some people can actually see the percept shift in their mind's eye[4]. Others, who are not picture thinkers, may not necessarily perceive the 'shape-shifting' as their world changes. The 'esemplastic' nature has been shown by experiment: an ambiguous image has multiple interpretations on the perceptual level. The question, "Is the glass half empty or half full?" serves to demonstrate the way an object can be perceived in different ways.Just as one object can give rise to multiple percepts, so an object may fail to give rise to any percept at all: if the percept has no grounding in a person's experience, the person may literally not perceive it.The processes of perception routinely alter what humans see. When people view something with a preconceived concept about it, they tend to take thoseconcepts and see them whether or not they are there. This problem stems from the fact that humans are unable to understand new information, without the inherent bias of their previous knowledge. A person’s knowledge creates his or her reality as much as the truth, because the human mind can only contemplate that to which it has been exposed. When objects are viewed without understanding, the mind will try to reach for something that it already recognizes, in order to process what it is viewing. That which most closely relates to the unfamiliar from our past experiences, makes up what we see when we look at things that we don’t comprehend.[5]This confusing ambiguity of perception is exploited in human technologies such as camouflage, and also in biological mimicry, for example by Peacock butterflies, whose wings bear eye markings that birds respond to as though they were the eyes of a dangerous predator. Perceptual ambiguity is not restricted to vision. For example, recent touch perception research Robles-De-La-Torre & Hayward 2001 found that kinesthesia based hapticperceptionstrongly relies on the forces experienced during touch.[6]Cognitive theories of perception assume there is a poverty of stimulus. This (with reference to perception) is the claim that sensations are, by themselves, unable to provide a unique description of the world. Sensations require 'enriching', which is the role of the mental model. A different type of theory is the perceptual ecology approach of James J. Gibson. Gibson rejected the assumption of a poverty of stimulus by rejecting the notion that perception is based in sensations. Instead, he investigated what information is actually presented to the perceptual systems. He and the psychologists who work within thisparadigm detailed how the world could be specified to a mobile, exploring organism via the lawful projection of information about the world into energy arrays. Specification is a 1:1 mapping of some aspect of the world into a perceptual array; given such a mapping, no enrichment is required and perception is direct perception.Preconceptions can influence how the world is perceived. For example, one classic psychological experiment showed slower reaction times and less accurate answers when a deck of playing cards reversed the color of the suit symbol for some cards (e.g. red spades and black hearts).[7]There is also evidence that the brain in some ways operates on a slight "delay", to allow nerve impulses from distant parts of the body to be integrated into simultaneous signals.[8]
- An ecological understanding of perception derived from Gibson's early work is that of "perception-in-action", the notion that perception is a requisite property of animate action; that without perception action would be unguided, and without action perception would serve no purpose. Animate actions require both perception and motion, and perception and movement can be described as "two sides of the same coin, the coin is action". Gibson works from the assumption that singular entities, which he calls "invariants", already exist in the real world and that all that the perception process does is to home in upon them. A view known as social constructionism (held by such philosophers as Ernst von Glasersfeld) regards the continual adjustment of perception and action to the external input as precisely what constitutes the "entity", which is therefore far from being invariant.[9]Glasersfeld considers an "invariant" as a target to be homed in upon, and a pragmatic necessity to allow an initial measure of understanding to be established prior to the updating that a statement aims to achieve. The invariant does not and need not represent an actuality, and Glasersfeld describes it as extremely unlikely that what is desired or feared by an organism will never suffer change as time goes on. This social constructionist theory thus allows for a needful evolutionary adjustment.[10]A mathematical theory of perception-in-action has been devised and investigated in many forms of controlled movement, and has been described in many different species of organism using the General Tau Theory. According to this theory, tau information, or time-to-goal information is the fundamental 'percept' in perception.
- Gestalt psychology or gestaltism (German: Gestalt - "essence or shape of an entity's complete form") of the Berlin School is a theory of mind and brain positing that the operational principle of the brain is holistic, parallel, and analog, with self-organizing tendencies. The Gestalt effect refers to the form-forming capability of our senses, particularly with respect to the visual recognition of figures and whole forms instead of just a collection of simple lines and curves. In psychology, gestaltism is often opposed to structuralism and Wundt. The phrase "The whole is greater than the sum of the parts" is often used when explaining Gestalt theory. (See History of Psychology by David Hothersall (2004), chapter seven, for complete history)
- OriginsThe concept of Gestalt was first introduced in contemporary philosophy and psychology by Christian von Ehrenfels (a member of the School of Brentano). The idea of Gestalt has its roots in theories by Johann Wolfgang von Goethe, Immanuel Kant, and Ernst Mach. Max Wertheimer's unique contribution was to insist that the "Gestalt" is perceptually primary, defining the parts of which it was composed, rather than being a secondary quality that emerges from those parts, as von Ehrenfels's earlier Gestalt-Qualität had been.Both von Ehrenfels and Edmund Husserl seem to have been inspired by Mach's work BeiträgezurAnalysederEmpfindungen (Contributions to the Analysis of the Sensations, 1886), in formulating their very similar concepts of Gestalt and Figural Moment, respectively.Early 20th century theorists, such as Kurt Koffka, Max Wertheimer, and Wolfgang Köhler (students of Carl Stumpf) saw objects as perceived within an environment according to all of their elements taken together as a global construct. This 'gestalt' or 'whole form' approach sought to define principles of perception -- seemingly innate mental laws which determined the way in which objects were perceived.These laws took several forms, such as the grouping of similar, or proximate, objects together, within this global process. Although Gestalt has been criticized for being merely descriptive, it has formed the basis of much further research into the perception of patterns and objects ( Carlson et al. 2000), and of research into behavior, thinking, problem solving and psychopathology.It should also be emphasized that Gestalt psychology is distinct from Gestalt psychotherapy. One has little to do with the other.
- The investigations developed at the beginning of the 20th century, based on traditional scientific methodology, divided the object of study into a set of elements that could be analyzed separately with the objective of reducing the complexity of this object. Contrary to this methodology, the school of Gestalt practiced a series of theoretical and methodological principles that attempted to redefine the approach to psychological research.The theoretical principles are the following:Principle of Totality - The conscious experience must be considered globally (by taking into account all the physical and mental aspects of the individual simultaneously) because the nature of the mind demands that each component be considered as part of a system of dynamic relationships.Principle of psychophysical isomorphism - A correlation exists between conscious experience and cerebral activity.Based on the principles above the following methodological principles are defined:Phenomenon Experimental Analysis - In relation to the Totality Principle any psychological research should take as a starting point phenomena and not be solely focused on sensory qualities.Biotic Experiment - The School of Gestalt established a need to conduct real experiments which sharply contrasted with and opposed classic laboratory experiments. This signified experimenting in natural situations, developed in real conditions, in which it would be possible to reproduce, with higher fidelity, what would be habitual for a subject.
- PropertiesThe key principles of Gestalt systems are emergence, reification, multistability and invariance.Emergence is the process of complex pattern formation from simpler rules. It demonstrated by the perception of the Dog Picture, which depicts aDalmatian dog sniffing the ground in the shade of overhanging trees. The dog is not recognized by first identifying its parts (feet, ears, nose, tail, etc.), and then inferring the dog from those component parts. Instead, the dog is perceived as a whole, all at once. However, this is a description of what occurs in vision and not an explanation. Gestalt theory does not explain how the percept of a dog emerges.
- Reification is the constructive or generative aspect of perception, by which the experienced percept contains more explicit spatial information than the sensory stimulus on which it is based.For instance, a triangle will be perceived in picture A, although no triangle has actually been drawn. In pictures B and D the eye will recognize disparate shapes as "belonging" to a single shape, in C a complete three-dimensional shape is seen, where in actuality no such thing is drawn.Reification can be explained by progress in the study of illusory contours, which are treated by the visual system as "real" contours.See also: Reification (fallacy)
- Multistability (or multistable perception) is the tendency of ambiguous perceptual experiences to pop back and forth unstably between two or more alternative interpretations. This is seen for example in the Necker cube, and in Rubin's Figure/Vase illusion shown here. Other examples include the 'three-pronged widget' and artist M. C. Escher's artwork and the appearance of flashing marquee lights moving first one direction and then suddenly the other. Again, Gestalt does not explain how images appear multistable, only that theydo.Multistable perceptual phenomena are a form of perceptual phenomena in which there are unpredictable sequences of spontaneous subjective changes. While usually associated with visual perception, such phenomena can be found for auditory and olfactory percepts.ClassificationPerceptual multistability can be evoked by visual patterns that are too ambiguous for the human visual system to recognise with one unique interpretation. Famous examples include the Necker cube, structure from motion, monocular rivalry and binocular rivalry, but many more visually ambiguous patterns are known. Since most of these images lead to an alternation between two mutually exclusive perceptual states, they are sometimes also referred to as bistable perception [1].Auditory and olfactory examples can occur when there are conflicting and so rivaling inputs into the two ears[2] or two nostrils.[3][edit]CharacterizationTransitions from one percept to its alternative are called perceptual reversals. They are spontaneous and stochastic events which cannot be eliminated by intentional efforts (although some control over the alternation process is learnable). Reversal rates vary drastically between stimuli and observers, and has been found to be slower for people with Bipolar disorder ("sticky" interhemispheric switch in bipolar disorder) [4].[edit]Cultural historyHuman interest in these phenomena can be traced back to antiquity. The fascination of multistable perception probably comes from the active nature of endogenous perceptual changes or from the dissociation of dynamic perception from constant sensory stimulation. Multistable perception was a common feature in the artwork of the Dutch lithographer M. C. Escher, who was strongly influenced by mathematical physicists such as Roger Penrose.[edit]Real world examplesPhotographs of craters, from either the moon or other planets including our own, can exhibit this phenomenon. Craters, in stereo imaging, such as our eyes, should appear to be pit-like structures. However in mono-vision, such as that of photographs, the elimination of our depth perception causes multistable perception to take over, and this can cause the craters to inverse their depth values and instead look like plateaus rather than pits. Sometimes rotating the image so that the photographic direction of the source of light matches a light source in the room can cause the correct perception to suddenly switch.A pop culture example can be found in Crow T. Robot, a puppet character on Mystery Science Theater 3000. At times, the puppet appears to be speaking to the audience instead of facing the screen due to the way his head curves.
- Invariance is the property of perception whereby simple geometrical objects are recognized independent of rotation, translation, and scale; as well as several other variations such as elastic deformations, different lighting, and different component features. For example, the objects in A in the figure are all immediately recognized as the same basic shape, which are immediately distinguishable from the forms in B. They are even recognized despite perspective and elastic deformations as in C, and when depicted using different graphic elements as in D. Computational theories of vision, such as those by David Marr, have had more success in explaining how objects are classified.Emergence, reification, multistability, and invariance are not necessarily separable modules to be modeled individually, but they could be different aspects of a single unified dynamic mechanism.[ci
- The fundamental principle of gestalt perception is the law of prägnanz (German for pithiness) which says that we tend to order our experience in a manner that is regular, orderly, symmetric, and simple. Gestalt psychologists attempt to discover refinements of the law of prägnanz, and this involves writing down laws which hypothetically allow us to predict the interpretation of sensation, what are often called "gestalt laws".[1] These include:Law of Closure — The mind may experience elements it does not perceive through sensation, in order to complete a regular figure (that is, to increase regularity).Law of Similarity — The mind groups similar elements into collective entities or totalities. This similarity might depend on relationships of form, color, size, or brightness.Law of Proximity — Spatial or temporal proximity of elements may induce the mind to perceive a collective or totality.Law of Symmetry (Figure ground relationships)— Symmetrical images are perceived collectively, even in spite of distance.Law of Continuity — The mind continues visual, auditory, and kinetic patterns.Law of Common Fate — Elements with the same moving direction are perceived as a collective or unit.
- Gestalt views in psychologyGestalt psychologists find it is important to think of problems as a whole. Max Wertheimer considered thinking to happen in two ways: productive and reproductive.[1]Productive thinking is solving a problem with insight.This is a quick insightful unplanned response to situations and environmental interaction.Reproductive thinking is solving a problem with previous experiences and what is already known. (1945/1959).This is a very common thinking. For example, when a person is given several segments of information, he/she deliberately examines the relationships among its parts, analyzes their purpose, concept, and totality, he/she reaches the "aha!" moment, using what is already known. Understanding in this case happens intentionally by reproductive thinking.Other Gestalts psychologist Perkins believes insight deals with three processes:1) Unconscious leap in thinking.[1].2) The increased amount of speed in mental processing.3) The amount of short-circuiting which occurs in normal reasoning.[2]Other views going against the Gestalt psychology are:1) Nothing-Special View2) Neo-Gestalts View3) The Three-Process ViewGestalt laws continue to play an important role in current psychological research on vision. For example, the object-based attention hypothesis[3] states that elements in a visual scene are first grouped according to Gestalt principles; consequently, further attentional resources can be allocated to particular objects.Gestalt psychology should not be confused with the Gestalt therapy of Fritz Perls, which is only peripherally linked to Gestalt psychology. A strictly Gestalt psychology-based therapeutic method is Gestalt Theoretical Psychotherapy, developed by the German Gestalt psychologist and psychotherapist Hans-Jürgen Walter.
- Applications in computer scienceThe Gestalt laws are used in user interface design. The laws of similarity and proximity can, for example, be used as guides for placing radio buttons. They may also be used in designing computers and software for more intuitive human use. Examples include the design and layout of a desktop's shortcuts in rows and columns. Gestalt psychology also has applications in computer vision for trying to make computers "see" the same things as humans do.[citation needed] http://www.interaction-design.org/encyclopedia/gestalt_principles_of_form_perception.htmlCriticismIn some scholarly communities, such as cognitive psychology and computational neuroscience, Gestalt theories of perception are criticized for being descriptive rather than explanatoryin nature. For this reason, they are viewed by some as redundant or uninformative. For example, Bruce, Green & Georgeson[4] conclude the following regarding Gestalt theory's influence on the study of visual perception:"The physiological theory of the Gestaltists has fallen by the wayside, leaving us with a set of descriptive principles, but without a model of perceptual processing. Indeed, some of their "laws" of perceptual organisation today sound vague and inadequate. What is meant by a "good" or "simple" shape, for example?"
- Physical basisThe biological foundation of the mind's eye is not fully understood. fMRI studies have shown that the lateral geniculate nucleus and the V1 area of the visual cortex are activated during mental imagery tasks.[1] Ratey writes:The visual pathway is not a one-way street. Higher areas of the brain can also send visual input back to neurons in lower areas of the visual cortex... As humans, we have the ability to see with the mind's eye -to have a perceptual experience in the absence of visual input. For example, PET scans have shown that when subjects, seated in a room, imagine they are at their front door starting to walk either to the left or right, activation begins in the visual association cortex, the parietal cortex, and the prefrontal cortex - all higher cognitive processing centers of the brain.[2]The rudiments of a biological basis for the mind's eye is found in the deeper portions of the brain below the neocortex, or where the center of perception exists. The thalamus has been found to be discrete to other components in that it processes all forms of perceptional data relayed from both lower and higher components of the brain. Damage to this component can produce permanent perceptual damage, however when damage is inflicted upon the cerebral cortex, the brain adapts to neuroplasticity to amend any occlusions for perception. It can be thought that the neocortex is a sophisticated memory storage warehouse in which data received as an input from sensory systems are compartmentalized via the cerebral cortex. This would essentially allow for shapes to be identified, although given the lack of filtering input produced internally, one may as a consequence, hallucinate - essentially seeing something that isn't received as an input externally but rather internal (i.e. an error in the filtering of segmented sensory data from the cerebral cortex may result in one seeing, feeling, hearing or experiencing something that is inconsistent with reality).Furthermore, the pineal gland is a hypothetical candidate for producing a mind's eye; Dr. Rick Strassman has postulated that during near death experiences (NDE's) and dreaming, the gland might secrete a hallucinogenic chemical 'N,N-Dimethyltryptamine' to produce internal visuals when external sensory data is occluded.[3][edit]PhilosophyThe use of the phrase mind's eye does not imply that there is a single or unitary place in the mind or brain where visual consciousness occurs. Various philosophers have criticized this view, Daniel Dennett being one of the best-known.[4] However, others, such as Johnjoe McFadden of the University of Surrey in the United Kingdom and the New Zealand-based neurobiologist Susan Pockett, have proposed that the brain's electromagnetic field is consciousness itself, thus causing the perception of a unitary location.[5][6]
- Picture thinking, visual thinking , visual/spatial learning or right brained learning is the common phenomenon of thinking through visual processing using the part of the brain that is emotional and creative to organize information in an intuitive and simultaneous way.Thinking in pictures, is one of a number of other recognized forms of non-verbal thought such as kinesthetic, musical and mathematical thinking. Multiple thinking and learning styles, including visual, kinesthetic, musical, mathematical and verbal thinking styles are a common part of many current teacher training courses.While visual thinking and visual learners are not synonymous, those who think in pictures have generally claimed to be best at visual learning. Also, while preferred learning and thinking styles may differ from person to person, precluding perceptual or neurological damage or deficits diminishing the use of some types of thinking, most people (visual thinkers included) will usually employ some range of diverse thinking and learning styles whether they are conscious of the differences or not.Concepts related to visual thinking have played an important role in art and design education over the past several decades. Important literature on this subject includes Rudolf Arnheim's 1969 book "Visual Thinking", Robert McKim's "Experiences in Visual Thinking" (1971), and Betty Edwards' "Drawing on the Right Side of the Brain" (1979).Controversy about visual thinking[edit]Eidetic MemoryEidetic Memory (photographic memory) may co-occur in visual thinkers as much as in any type of thinking style as it is a memory function associated with having vision rather than a thinking style. Eidetic Memory can still occur in those with visual agnosia, who, unlike visual thinkers, may be limited in the use of visualization skills for mental reasoning.[edit]DyslexiaAs dyslexia is believed to affect up to 17% percent of the population and Visual thinking is predominant in around 60%-65%[citation needed] of the population, there is no clear indication of a link between visual thinking and dyslexia. As visual thinking is the most common mode of thought, it might be expected that the incidence of visual thinking in the dyslexia community would be reflective of that in the general population, around 60%-65%[citation needed] of each population.[edit]AutismVisual thinking has been argued by Temple Grandin to be an origin for delayed speech in people with autism.[1] However, picture thinking itself is only one form of "non-linguistic thinking" which includes physical (kinaesthetic), aural (musical) and logical (mathematical/systems) style of thought.[2] Among those whose main form of thought and learning style is a non-linguistic form, visual thinking is the most common, while most people have a combination of thinking and learning styles. It has been suggested that visual thinking has some necessary connection with autism. However, given that current statistics by the National Autistic Society UK put the incidence of ASD around 1 in 100 people[3] and that up to 60%-65%[citation needed] of the population think in pictures, it cannot be concluded that visual thinking has any necessary connection with autism. Moreover, unless those with autism have sensory-perceptual disorders limiting their capacity to develop visual thinking, such as visual agnosias or blindness since infancy, many people with autism, just as many non-autistic people, are equally likely to think in pictures. As visual thinking is the most common mode of thought, it might be expected that the incidence of visual thinking in the autistic community may be reflective of that in the general population, being around 60%-65%[citation needed] of the general population.[edit]Spatial-Temporal Reasoning or Spatial VisualizationVisual thinkers describe thinking in pictures. As approximately 60%-65%[citation needed] of the general population, it's possible that a visual thinker may be as likely as any human being to also have good spatial-temporal reasoning or visual spatial ability without the two having any necessary direct relationship. Acute spatial ability is also a trait of kinesthetic learners (those who learn through movement, physical patterning and doing) and logical thinkers (mathematical thinkers who think in patterns and systems) who may not be strong visual thinkers at all. Similarly, visual thinking has been described as seeing words as a series of pictures which, alone, is not exactly the same phenomena spatial-temporal reasoning.It has to be understood however, that the reasoning employed here uses the fact that these 60 to 65%[citation needed] percent of people are people who "strongly" or "sometimes" use thinking in pictures, but also use other forms of thinking. They think in pictures almost to the exclusion of other kinds of thinking. Such persons, real "picture thinkers", make up only a very small percentage of the population. Thus the "Controversy" described above might be moot when considering this.[edit]ResearchResearch by Child Development Theorist Linda Kreger Silverman suggests that less than 30% of the population strongly uses visual/spatial thinking, another 45% uses both visual/spatial thinking and thinking in the form of words, and 25% thinks exclusively in words. According to Kreger Silverman, of the 30% of the general population who use visual/spatial thinking, only a small percentage would use this style over and above all other forms of thinking, and can be said to be 'true' "picture thinkers".[4]Contrary to the apparent lack of interest in visual thinking in the US, in the Netherlands there is a strong and growing interest in this phenomenon. As a result from increased media coverage during the last few years, there is an acceptance of its existence by the general public[citation needed], although criticism remains from some Dutch psychologists and development theorists[5]. Since its discovery a decade ago, a significant amount of empirical evidence in favor of its existence has been discovered, and much research is being done on visual thinking a Dutch nonprofit organization named the "Maria J. KrabbeStichtingBeelddenken" [1]. They've also developed a test, named the "Ojemannwereldspel", to identify children who rely primarily on visual-spatial thinking, in which children are asked to build a village with toy houses and then replicate it a few days later.
- Is the glass half empty or half full?From Wikipedia, the free encyclopediaHalf empty or half full?Is the glass half empty or half full? is a common expression, used rhetorically to indicate that a particular situation could be a cause foroptimism (half full) or pessimism (half empty); or as a general litmus test to simply determine if an individual is an optimist or a pessimist. The purpose of the question is to demonstrate that the situation may be seen in different ways depending on one's point of view and that there may be opportunity in the situation as well as trouble.This idiom is used to explain how people perceive events and objects. Perception is unique to every individual and is simply one's interpretation of reality. The phrase "Is the glass half empty or half full" can be referred to as a philosophical question.
- Ambiguous images are optical illusion images which are crafted to exploit graphical similarities and other properties of visual systeminterpretation between two or more distinct image forms. These are famous for inducing the phenomenon of multistable perception.Some often used synonymous terms are reversal images, puzzle images and perceptual rivalry.
- Alice in Wonderland syndrome (AIWS, named after the novel written by Lewis Carroll), also known as Todd's syndrome[1], is a disorienting neurological condition which affectshuman perception. Sufferers may experience micropsia, macropsia, and/or size distortion of other sensory modalities. A temporary condition, it is often associated with migraines, brain tumors, and the use of psychoactive drugs.[citation needed] It can also present as the initial sign of the Epstein-Barr Virus (see mononucleosis). Anecdotal reports suggests that the symptoms of AIWS are fairly common in childhood[citation needed], with many people growing out of them in their teens. It appears that AIWS is also a common experience at sleep onset.Signs and symptomsEye components are entirely normal. The AIWS is a result of change in perception as opposed to the eyes themselves malfunctioning. The hallmark sign of AIWS is a migraine, and may in part be caused by the symptom itself. AIWS affects the sufferer's sense of visual, sensation, touch, hearing as well as one's own body image.The most prominent and often most disturbing symptom is that of altered body image: the sufferer will find that they are confused as to the size and shape of parts of (or all of) their body.The eyes themselves are normal, but the sufferer 'sees' objects with the wrong size or shape and/or finds that perspective is incorrect. This can mean that people, cars, buildings, etc. look smaller or larger than they should be, or that distances look incorrect; for example a corridor may appear to be very long, or the ground may appear too close.In addition, some people may experience more intense and overt hallucinations, seeing things that are not there and misinterpreting events and situations in conjunction with a high fever.[edit]DiagnosisBecause AIWS is a disturbance of perception rather than a specific physiological change to the body's systems, the diagnosis can be presumed when other, physical causes have been ruled out and if the patient presents with migraines, altered senses and complains of onset during the day (although it can occur night).[edit]TreatmentTreatment is the same as that for other migraine prophylaxis: anticonvulsants, antidepressants, beta blockers, and calcium channel blockers, along with strict adherence to the migrainediet.[edit]PrognosisWhatever the cause, the distortions can recur several times a day and can last from a few minutes to a few weeks. Understandably, the sufferer can become alarmed, frightened, and even panic-stricken. Fortunately, treatment is straight-forward and with an excellent prognosis. This is according to Dr Randolph Evans, a clinician in Houston, Texas and Dr Loren Rolak, a clinician at the Marshfield Clinic in Marshfield, Wisconsin.[edit]EpidemiologyNo studies are available that display any correlation between age, gender or race. AIWS is thought to be relatively common among migraine sufferers and young children.[edit]References^ Longmore, Murray; Ian Wilkinson, Tom Turmezei, Chee Kay Cheung (2007). Oxford Handbook of Clinical Medicine. Oxford. pp. 686. ISBN 0-19-856837-1.PMID 12207198Kew, J., Wright, A., & Halligan, P.W. (1998). Somesthetic aura: The experience of "Alice in Wonderland", The Lancet, 351,p1934
- Saṃjñā (Sanskrit; Devanagiri: संज्ञा) and sañña (Pāli; Devanagiri: सञ्ञा) can be translated as "perception" or "cognition."In the Early Buddhist literatureIn the early Buddhism of the Nikayas/Āgamas, saṃjñā/sañña is the third of the Five Aggregates (Skt.: skandha; Pali: khandha) which can be used to skillfully delineate phenomenological experiences during meditation.[1] Whether as one of the Five Aggregates, meditativeconcentration (samādhi) on the passing and rising (P. vipassana, S. vipaśyanā) of sañña can lead to mindfulness (P.sati, S. smṛti), clear comprehension (P. sampajanna, S. samprajaña) and even enlightenment and Arhantship (see Table).In the Pali Canon, sañña is frequently defined as:"It perceives blue, it perceives yellow, it perceives red, it perceives white."[2]In post-canonical Pali commentaries, the Visuddhimagga likens sañña to "a child without discretion."[3]