perception
American Heritage Dictionary:
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per·cep·tion
(pər-sĕp'shən) 
n.
n.
- The process, act, or faculty of perceiving.
- The effect or product of perceiving.
- Psychology.
- Recognition and interpretation of sensory stimuli based chiefly on memory.
- The neurological processes by which such recognition and interpretation are effected.
- Insight, intuition, or knowledge gained by perceiving.
- The capacity for such insight.
[Middle English percepcioun, from Old French percepcion, from Latin perceptiō, perceptiōn-, from perceptus, past participle of percipere, to perceive. See perceive.]
perceptional per·cep'tion·al adj.Britannica Concise Encyclopedia:
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perception
Process of registering sensory stimuli as meaningful experience. The differences between sensation and perception have varied according to how the terms are defined. A common distinction is that sensations are simple sensory experiences, while percepts are complex constructions of simple elements joined through association. Another is that perception is more subject to the influence of learning. Though hearing, smell, touch, and taste perceptions have all been explored, vision has received the most attention. Structuralist researchers such as Edward Bradford Titchener focused on the constituent elements of visual perceptions, whereas Gestalt psychology has stressed the need to examine organized wholes, believing humans are disposed to identifying patterns. Visual objects tend to appear stable despite continually changing stimulus features (such as ambient light, perspective, ground vs. figure arrangement), which enables an observer to match a perceived object with the object as it is understood to exist. Perceptions may be influenced by expectations, needs, unconscious ideas, values, and conflicts.
For more information on perception, visit Britannica.com.
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Those subjective experiences of objects or events that ordinarily result from stimulation of the receptor organs of the body. This stimulation is transformed or encoded into neural activity (by specialized receptor mechanisms) and is relayed to more central regions of the nervous system where further neural processing occurs. Most likely, it is the final neural processing in the brain that underlies or causes perceptual experience, and so perceptionlike experiences can sometimes occur without external stimulation of the receptor organs, as in dreams.
In contemporary psychology, interest generally focuses on perception or the apprehension of objects or events, rather than simply on sensation or sensory process. While no sharp line of demarcation between these topics exists, it is fair to say that sensory qualities are generally explicable on the basis of mechanisms within the receptor organ, whereas object and event perception entails higher-level activity of the brain. See also Hearing (human); Sensation; Vision.
Since objects or events are not experienced only through vision, the term perception obviously applies to other sense modalities as well. Certainly things and their movement may be experienced through the sense of touch. Such experiences derive from receptors in the skin (tactile perception), but more importantly, from the positioning of the fingers with respect to one another when an object is grasped, the latter information arising from receptors in the muscles and joints (haptic or tactual perception). The position of the parts of the body are also perceived with respect to one another whether they are stationary (proprioception) or in motion (kinesthesis), and the position of the body is experienced with respect to the environment through receptors sensitive to gravity such as those in the vestibular apparatus in the inner ear. Auditory perception yields recognition of the location of sound sources and of structures such as melodies and speech. Other sense modalities such as taste (gustation), smell (olfaction), pain, and temperature provide sensory qualities but not perceptual structures as do vision, audition, and touch, and thus are usually dealt with as sensory processes. See also Olfaction; Pain; Proprioception.
Constancy
By and large, these perceptual properties of objects remain remarkably constant despite variations in distance, slant, and retinal locus caused by movements of the observer. This fact, referred to as perceptual constancy, is perhaps the hallmark of perception and more than any other, serves to characterize the field of perception.
Examples of perceptual constancy are: size (except at very great distances, an object appears the same size whether seen nearby or far away, although the size of its image on the retina can be very different); shape (a circle seen from the side is perceived as a circle, although it appears as an ellipse on the retina); orientation (objects appear to keep the same orientation in space, independently of the orientation of the observer's head); and position (a fixed object remains perceived as stationary even when its image on the retina moves because of eye or head movements).
Motion perception
Perceived movement cannot simply be explained by the motion of an object's retinal image since image motion caused by observer or eye movement does not lead to perceived object movement. Moreover, an object tracked by smooth-pursuit eye movements will appear to move, although in that case there is essentially no motion of the object's image over the retina. Similarly, an afterimage will appear to move during eye movement even in a completely darkened room. Where ordinarily the movement of the retinal image caused by the moving eye is computed to signify “no object motion,” thus yielding position constancy (since the image motion and eye motion are equal in magnitude), the same computational rule must signify “object motion” in the case of the afterimage.
Form perception
Form perception means the experience of a shaped region in the field. Recognition means the experience that the shape is familiar. Identification means that the function or meaning or category of the shape is known. For those who have never seen the shape before, it will be perceived but not recognized or identified. For those who have, it will be perceived as a certain familiar shape and also identified. Recognition and identification obviously must be based on past experience, which means that through certain unknown processes, memory contributes to the immediate experience that one has, giving the qualities of familiarity and meaning.
The figure of a 4 in Fig. 1a is seen as one unit, separate from other units in the field, even if these units overlap. This means that the parts of the figure are grouped together by the perceptual system into a whole, and these parts are not grouped with the parts of other objects. This effect is called perceptional organization. There are other problems about form perception that remain to be unraveled. For example, the size of a figure can vary, as can its locus on the retina or even its color or type of contour, without affecting its perceived shape (Fig. 2).
Perceptual organization, (a) The figure of a four is immediately and spontaneously perceived despite the presence of other overlapping and adjacent lines, (b) The four, although physically present, is not spontaneously perceived and is even difficult to see when one knows it is there.
Transposition of form; the two shapes clearly look the same despite the difference in size.
A further fact about form perception is that it is dependent upon orientation. It is a commonplace observation that printed or written words are difficult to read when inverted, and faces look very odd or become unrecognizable when upside down. Simple figures also look different when their orientation is changed: a square looks like a diamond when tilted by 45°.
Geometrical illusions
Related to the topic of form perception is the misperception of the size or direction of parts of figures that constitutes many of the geometric illusions. In an illusion figure, one particular part is perceived to be either longer or shorter than another part, although they are objectively equal (Fig. 3a); or the direction of a contour is perceived to be different from that of another contour although they are the same (Fig. 3b). For reasons still not understood, the background or context of the rest of the figure affects these parts.
unequal, (b) The Poggendorff illusion in which the two oblique line segments are aligned with one another (that is, are collinear) but appear to be misaligned.">
Geometrical illusions, (a) The Ponzo illusion in which the two horizontal lines of equal length appear unequal, (b) The Poggendorff illusion in which the two oblique line segments are aligned with one another (that is, are collinear) but appear to be misaligned.
Innate or learned?
A central problem is whether the perception of properties such as form and depth or the achievement of veridical perception as in the constancies is innately determined or is based on past experience. By “innate” it is meant that the perception is the result of evolutionary adaptation and thus is present at birth or when the necessary neural maturation has occurred. By “past experience” it is meant that the perception in question is the end result of prior exposure to certain relevant patterns or conditions, a kind of learning process. Despite centuries of discussion of this problem, and considerable experimental work, there is still no final answer to the question. It now seems clear that certain kinds of perception are innate, but equally clear that past experience also is a determining factor. See also Intelligence.
Oxford Companion to the Body:
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perception
Our senses probe the external world, and they also tell us about ourselves as they monitor the positions of our limbs and the balance of our bodies. Through pain they signal injury and illness.
How we experience and know about external objects is a question that was discussed by the Greek philosophers and has been ever since. Planned experiments on perception, in the spirit of the physical sciences, were hardly attempted before the mid nineteenth century. They have revealed a surprising complexity of physiological and cognitive (knowledge-based) processes, of which we are normally unaware, though many can be demonstrated simply and dramatically, especially through the phenomena of illusions.
There is a long-standing tradition in philosophy that perception, especially touch and vision, gives undeniably true knowledge. For philosophers have generally sought certainty and often claimed it, whereas scientists (who are used to their theories being upset by new data) are more ready to settle for today's best bet. Many scientific instruments have been developed because of the unreliability or inadequacy of perception.
Perceptions are separate, and in several ways different, from conceptual understanding, for perception must work very fast (whereas we may take minutes or hours to ‘make up our minds’, and years to form new concepts). Also, it would be impossible for perception to draw upon all of our knowledge; and perceptions are of individual objects and events in present time, while concepts are abstract and generally timeless.
The evolution of mechanisms for the perception of objects and events at a distance (most completely through vision and hearing) freed organisms from the tyranny of reflex responses to immediate situations, and no doubt was a necessary precursor of all intelligence. It is a fairly new notion that perception itself is an intelligent activity, requiring still only partly understood problem-solving to infer the objective world from sensory signals. Earlier accounts, especially British Empiricism, portrayed sensory perception very differently, as a passive, undistorting window, through which the mind accepts sensations directly from objects. This is not consistent with physiological knowledge of the senses and the brain, nor with many phenomena, such as illusions of vision and hearing and touch. The notion of ‘direct perception’ is, however, still maintained by some followers of the American psychologist J. J. Gibson, perhaps by taking this aspect of his important writings too literally. Perception is not traditionally thought of as an intelligent activity; though the power, especially of vision, to probe distance gains the time needed for intelligent behaviour and for the intelligence of perception itself.
Are perceptions simply picked up by the senses passively, or are they created actively by the brain, or mind? This issue between passive or active perception is a long-standing debate, with significant implications, such as: what is ‘objective’ and what ‘subjective’? The philosopher John Locke (1690) suggested that there are primary characteristics, such as hardness and mass and extension of objects, in space and time — in the world before life, existing apart from mind — and secondary characteristics, created in minds or brains. Thus colours are not in the world, but are created within us, though related in complex ways to light and to the surfaces of objects. Sir Isaac Newton (Opticks, 1704) expressed clearly that red light is not itself red, but is: ‘red-making’:
…there is nothing else than a certain power and disposition to stir up the sensation of this or that colour. For as sound in a bell or musical string … is nothing but a trembling motion.Then (in Query 23 of Opticks) Newton speculates on something like a neural mechanism of vision:
Is not vision perform'd chiefly by the Vibrations of this (Eatherial) Medium, excited in the bottom of the eye of Rays of Light, and propagated through the solid, pellucid and uniform Capillamenta of the optic Nerves in the place (the ‘Sensorium’) of Sensation?The Empiricist school (of which, in their different ways, Locke and Newton were founders) also rejected the notion that minds can receive knowledge by direct intuition quite apart from sensory experience. Mind was now regarded as essentially isolated from the physical world — linked only by tenuous threads of nerve and by fallible inferences of what might be ‘out there’. Some people find this too unsettling to be true. But it is now generally accepted that perception depends on active, physiologically based, intelligent processes. This is not intuitively obvious, since perception seems so simple and easy and we know nothing of the processes in our brains by introspection. Seeing happens so fast and so effortlessly that it is hard to conceive the complexity of the processes that we now know are needed to interpret the nature of the visual world from sensory signals — processes that remain largely beyond the capabilities of the most advanced computers.
Paradoxically, this takes us to concepts familiar to engineers and useful for physiology. We may describe the organs of the senses as ‘transducers’, which accept patterns of energy from the external world, signalling them as coded messages to be read by the brain, which uses these patterns to infer the state-of-play of the surrounding world, and something of the body's own states. Another useful engineering concept is that of ‘channels’. The various senses feed specialized ‘brain modules’ through neural channels, discovered by physiological and ‘psychophysical’ (perceptual) experiments. Thus, as Thomas Young suggested in 1801, colour vision is created from information about the wavelength of light transmitted through three channels, red, green, and blue, responding to light of long, medium, and short wavelength, respectively. All the hundreds of colours we can see are interpretations by the brain of the relative activity of these three colour channels. The three colour channels correspond, initially, to three kinds of light-catching photopigment in the photoreceptors, called cones, in the retina.
There are similar neural channels representing the orientation of lines and edges, and for movement, as first shown by direct physiological recording from nerve cells in the visual cortex of cats by the physiologists D. H. Hubel and T. N. Wiesel in 1962. There are channels for many other visual characteristics: stereoscopic (3-D) depth, texture, spatial size, etc. The ear has many different frequency channels, and there are scores of channels for the sense of ‘touch’, including those for various kinds of pain, for tickle, and for monitoring the positions of the limbs and the stretch of muscles in order to control movement. We are unaware of activity in these sensory channels themselves. Somehow outputs from the many channels are combined to give consistent perceptions. Small discrepancies — such as the delay in sound between seeing a ball hit a bat and hearing the impact — are rejected or pulled into place to maintain a consistent world. Equally, whole objects are somehow assembled from the many signals in different sensory channels that define them. But how this (‘the binding problem’) is done is not understood.
The theory that perception is ‘cognitive’, depending on inferences from essentially inadequate sensory signals, was first clearly proposed by the German polymath physicist, physiologist, and psychologist, Hermann von Helmholtz (1821-94). He called perceptions ‘unconscious inferences’. We might say that they (our most intimate experiences and knowledge) are simply hypotheses, essentially like the predictive hypotheses of science — though not always agreeing in particular accounts.
More recently, attempts to program computers to see (an important component of artificial intelligence) has shown how hard it is to infer objects from sensed data. The most influential attempt, by physiologist David Marr, suggested that object shapes are derived from the retinal images via three essential stages:
(i) the ‘primal sketch(es) ’, describing intensity changes and locations or critical features and local geometric relations;
(ii) the ‘2 1/2-D sketch’, giving a preliminary analysis of depth, surface discontinuities, and so on, in a frame that is centred on the viewer;
(iii) the ‘3-D model representation’, in an object-centred co-ordinate system, so that we see objects much as they really are in 3-D space, though they are presented from just one viewpoint. Marr supposed that this last stage is aided by restraints on the range of likely solutions to the problem of what is ‘out there’. These information-processing constraints are set by assuming typical object shapes; for example, that the shapes of many objects, such as other human beings, are modified cylinders. Interestingly, the painter Paul Cézanne came close to this notion in 1904:
Treat nature by the cylinder, the sphere, the cone, everything in proper perspective so that each side of an object or a plane is directed towards a central point … nature for us men is more depth than surface.David Marr stressed the importance of immediate, passive processing of sensory signals, over active, cognitive ‘top down’ application of knowledge gained from the past. This is a central controversy, currently moving towards greater cognitive ‘top down’ contributions, especially for vision. When computers (or the form of computing known as ‘neural nets’) can access vast amounts of knowledge appropriately, in real time, they might share our miracle of perception.
Artists and scientists can teach each other secrets of perception (as by Gombrich, 1960), though such cross-cultural communication is not easy for most of us.
— Richard L. Gregory
Bibliography
- Gibson, J. J. (1950). Perception of the visual world. Houghton Mifflin, Boston MA.
- Gibson, J. J. (1966). The senses considered as perceptual systems. Houghton Mifflin, Boston MA.
- Gombrich, E. (1960). Art and illusion. Phaidon, London.
- Gregory, R. L. (1966,
fifth edn 1998). Eye and brain. Oxford University Press. - Hubel, D. and Wiesel, T. N. (1962). Receptive fields, binocular interaction and functional architecture in the cat's visual cortex. Journal of Physiology,
160 , 106-54. - Marr, D. (1982). Vision. W. H. Freeman, San Francisco.
- Zeki, S. (1993). A vision of the brain. Blackwell, Oxford
See also illusions; sensation; senses, extensions of; sensory integration; vision.
Roget's Thesaurus:
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perception
noun
- The condition of being aware: awareness, cognizance, consciousness, sense. See knowledge/ignorance.
- That which exists in the mind as the product of careful mental activity: concept, conception, idea, image, notion, thought. See thoughts.
Oxford Dictionary of Philosophy:
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perception
A fundamental philosophical topic both for its central place in any theory of knowledge, and its central place in any theory of consciousness. Philosophy in this area is constrained by a number of properties that we believe to hold of perception. (i) It gives us knowledge of the world around us. (ii) We are conscious of that world by being aware of ‘sensible qualities’: colours, sounds, tastes, smells, felt warmth, and the shapes and positions of objects in the environment. (iii) Such consciousness is effected through highly complex information channels, such as the output of the three different types of colour-sensitive cells in the eye, or the channels in the ear for interpreting pulses of air pressure as frequencies of sound. (iv) There ensues even more complex neuro-physiological coding of that information, and eventually higher-order brain functions bring it about that we interpret the information so received. (Much of this complexity has been revealed by the difficulties of writing programs enabling computers to recognize quite simple aspects of the visual scene.) The problem is to avoid thinking of there being a central, ghostly, conscious self, fed information in the same way that a screen is fed information by a remote television camera. Once such a model is in place, experience will seem like a veil getting between us and the world, and the direct objects of perception will seem to be private items in an inner theatre or sensorium. The difficulty of avoiding this model is especially acute when we consider the secondary qualities (see primary/secondary qualities) of colour, sound, tactile feelings, and taste, which can easily seem to have a purely private existence inside the perceiver, like sensations of pain. Calling such supposed items names like sense data or percepts exacerbates the tendency. But once the model is in place, the first property, that perception gives us knowledge of the world around us, is quickly threatened, for there will now seem little connection between these items in immediate experience and any independent reality. Reactions to this problem include scepticism and idealism.
A more hopeful approach is to claim that the complexities of (iii) and (iv) explain how we can have direct acquaintance of the world, rather than suggesting that the acquaintance we do have is at best indirect. It is pointed out that perceptions are not like sensations, precisely because they have a content, or outer-directed nature. To have a perception is to be aware of the world as being such and such a way, rather than to enjoy a mere modification of sensation. But such direct realism has to be sustained in the face of the evident personal (neurophysiological and other) factors determining how we perceive. One approach is to ask why it is useful to be conscious of what we perceive, when other aspects of our functioning work with information determining responses without any conscious awareness or intervention. A solution to this problem would offer the hope of making consciousness part of the natural world, rather than a strange optional extra. See also observation, myth of the given.
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The mental process by which the brain interprets and gives meaning to information it receives from sense organs. Perception depends on both the psychological and physiological characteristics of the perceiver, in addition to the nature of the stimuli.
Columbia Encyclopedia:
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perception
perception, in psychology, mental organization and interpretation of sensory information. The Gestalt psychologists studied extensively the ways in which people organize and select from the vast array of stimuli that are presented to them, concentrating particularly on visual stimuli. Perception is influenced by a variety of factors, including the intensity and physical dimensions of the stimulus; such activities of the sense organs as effects of preceding stimulation; the subject's past experience; attention factors such as readiness to respond to a stimulus; and motivation and emotional state of the subject. Stimulus elements in visual organization form perceived patterns according to their nearness to each other, their similarity, the tendency for the subject to perceive complete figures, and the ability of the subject to distinguish important figures from background. Perceptual constancy is the tendency of a subject to interpret one object in the same manner, regardless of such variations as distance, angle of sight, or brightness. Through selective attention, the subject focuses on a limited number of stimuli, and ignores those that are considered less important. Depth perception, considered to be innate in most animals, is produced by a variety of visual cues indicating perspective, and by a slight disparity in the images of an object on the two retinas. An absolute threshold is the minimal physical intensity of a stimulus that a subject can normally perceive, whereas a difference threshold is the minimal amount of change in a stimulus that can be consciously detected by the subject. Recent studies have shown that stimuli are actually perceived in the brain, while sensory organs merely gather the signals. William Dobelle's research, for instance, has offered significant hope for the blind.
Oxford Companion to the Mind:
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perception
Our senses probe the external world. They also tell us about ourselves, as they monitor positions of the limbs and the balance of our bodies, and through pain they signal injury and illness. More subtly, there are innumerable internal signals monitoring everyday physiological activities, and conveying and maintaining our well-being; though little of this enters our consciousness. In perception of objects and pictures, as Sir Ernst Gombrich (1950) realized to such good effect, art and science meet.
Just how we know things through sensory experience is a question that was discussed by the Greek philosophers and has continued to be discussed ever since. But, perhaps curiously, planned experiments in the spirit of the physical sciences were hardly attempted much earlier than the mid-19th century. Since then, the experimental study of perception has yielded fundamental knowledge for physiology and psychology, especially from the outstanding work of Hermann von Helmholtz (1867). It has revealed many surprises in the form of processes of which we are unaware, though they can often be demonstrated simply and dramatically as by the phenomena of illusions. The study of perception, especially of vision and hearing and touch, has allowed psychology to grow from its philosophical roots into an experimental science; yet deeply puzzling philosophical questions remain, especially over the role of consciousness. It is puzzling, both that we are aware of so little of perception, and that we have any awareness or consciousness.
There is a long-standing tradition in philosophy that perception gives undeniably true knowledge. Philosophers have traditionally sought certainty, and often claimed it, whereas scientists — who are used to their theories being modified and upset by new data — generally settle for today's best bet. Philosophers have a heavy investment in the reliability of perception, for they stake their all on the certainty of knowledge from the senses to provide secure premisses for their arguments based on experience. Scientists, on the other hand, who are used to errors in measurement and observations, have found it necessary to check, and compare, and repeat observations as they do not expect reliability from the senses. Indeed, many scientific instruments have been developed precisely because of the limitations or the unreliability of perception: for it is easy to produce and demonstrate all manner of dramatic illusions, which could hardly occur if perception were direct reliable knowledge. Yet although illusions of object perception have been discussed by philosophers from Aristotle to Berkeley and more recently, philosophy generally has paid more attention to errors of logic and ambiguity of language, than to fallibilities of perception.
Philosophers are traditionally impressed by the undeniability of the 'raw experience' of sensations. The sensation of toothache may be undeniable; but are perceptions of objects, and things happening, similarly infallible? One would think so if one believed that perceptions are simply sensations; but we now regard perceptions as giving us knowledge, albeit surprisingly indirectly, of the causes or sources of sensations — such as the states of our bodies, and especially objects in the environment — rather than of sensations themselves. It is now clear that there are vast, still largely mysterious perceptual jumps, intelligent leaps of the mind, which may land on error. One can, indeed, be wrong about the cause of toothache!
It is worth asking why we have both perceptions and conceptions of the world. Why is perception somehow separate, and in several ways different from our conceptual understanding? Very likely it is because perception, in order to be useful, must work very fast; whereas we may take minutes, hours, or years, forming concepts.
Perception is not traditionally thought of as an intelligent activity, though the power, especially of vision, to probe distance gains time needed for intelligent reactions to on-going events. It can be argued (see stimulus) that the development of distance perception freed organisms from the tyranny of reflexes, and allowed perception to be intelligent.
Are perceptions picked up by the senses, or are they created internally by the perceiver? This question about the passivity or activity of perception is long-standing, and still debated. If sensations are created by the brain, a notion that receives strong support from physiology (see visual brain in action; visual system: environmental influences; visual system: organization), we should expect to find, as we do, a vast amount of brain activity for perception. Whereas, if perceptions are simply 'picked up' (Gibson 1950, 1966), the brain would have little to do. But a very great deal goes on, physiologically and cognitively.
This raises the old question: what is 'objective' and what is 'subjective'? The philosopher John Locke (1690), who was well aware of the new science of his time, suggested that there are two kinds of characteristics: primary characteristics, such as hardness, mass, and extension of objects in space and time — being in the world before life, and quite apart from mind — and secondary characteristics, which are created by brain–mind. Thus colours are not in the world, but are created within us, though they are related in complex ways to light and the surfaces of objects.
It is generally accepted that Locke's 'primary' characteristics are present independently of mind and perception, and it is clear that 'secondary' characteristics are affected by states of the sensing organism; because colours change with adaptation, and everything appears tinged with yellow if we have jaundice. Isaac Newton, writing on sensations of colour in Opticks (1704), agreed with his friend Locke, saying that red light is not itself red, but is 'red-making'. Spelling this out, he said of light rays: 'there is nothing else than a certain power and disposition to stir up the sensation of this or that colour. For as sound in a bell or musical string ... is nothing but a trembling motion.' Then (in Query 23), he specifies something of the neural mechanism of vision that leads to the mysterious seat of sensation: 'Is not vision perform'd chiefly by the Vibrations of this (Eatherial) Medium, excited in the bottom of the eye by Rays of Light, and propagated through the solid, pellucid and uniform Capillamenta of the optic Nerves in the place (the "Sensorium") of Sensation?'
The empiricist school, of which Locke and Newton were founders, rejected the notion that had been the basis of much philosophy, that minds can receive knowledge by direct intuition, quite apart from perception. Mind was now regarded as essentially isolated from the physical world, linked by tenuous threads of nerve, sending signals to the brain, which has to make sense of sensations. At the same time, there were attempts to discover 'laws' of mind, corresponding in some ways to the laws of physics, though seldom if ever seen as being in quite the same category. Newton did, however, write (in a letter to Henry Oldenburg, secretary of the Royal Society): 'I suppose the Science of colours will be granted Mathematicall and as certain as any part of Optiques'. Laws of colour mixture were developed later, especially following the work of Thomas Young, who made the important discovery in 1801 that all the spectral colours can be produced by mixture of various intensities of only three spectral lights. This took the sensations of colour somewhat outside the realm of physics, and yet they were seen as bound by certain laws. So evidently there could be a lawful science of sensation and of mind (see colour vision: brain mechanisms; colour vision: eye mechanisms). Newton fully appreciated that colour sensations are not always given by light, as he said (Opticks, Query 16): 'When a Man in the dark presses either corner of his Eye with his finger, he will see a Circle of Colours like those of a Peacock's Tail.' At the same time, much like Pythagoras linking music with the physics of vibrating strings, Newton tried to describe aesthetics according to physical principles (Query 14):
It is now generally accepted that perception depends on active physiologically based processes; but this notion is non-intuitive, for we know nothing of such processes or mechanisms by introspection, by consciousness. Moreover, perceiving objects around us seems so simple and easy! It happens so fast, and so effortlessly it is hard to conceive the complexity of the processes that we now know are involved.
This takes us to concepts familiar to engineers. It is not misleading to describe the organs of the senses — the eyes, ears, touch receptors, and so on — as 'transducers' that accept and signal patterns of energy from the external world, as coded messages, read by the brain to infer the state-of-play of the surrounding world. Another useful engineering concept is that of 'channels'. The various senses: touch and vision and hearing, and so on, are each subdivided into channels which generally can only be discovered by experiment. Thus, for example, though this was not at all realized before Young's (1801) colour mixture experiment, colour vision works with just three channels, responding to long-wavelength red, medium-wavelength green, and short-wavelength blue, light, respectively. All the hundreds of colours we see are, neurally, mixtures from these three colour channels (see yellow.) Then there are channels representing the orientation of lines and edges, and channels for movement, as shown by direct physiological recording from the visual cortex, demonstrated dramatically by David Hubel and Torstin Wiesel (1962), who received the Nobel Prize for this outstanding work. By less physiologically direct methods, such as selective adaptation, it has been found that there are more or less independent channels for spatial frequency and many other visual characteristics. The ear has many frequency channels (see hearing), and there is a score of channels for touch, various kinds of pain, tickle, and for monitoring the positions of the limbs and setting muscle tensions for moving them appropriately (see pain; tickling). Small discrepancies, such as delay in sound between seeing a ball hit by a bat and hearing the impact, are rejected or pulled into place, to maintain a consistent world. Here, the constancies (see colour perception: constancy and contrast) are very important; they modify sensations and perceptions to fit what should be there!
For signalling by the senses, as from instruments, it is important to appreciate the range of likely or possible objects that may be present (see information rate of vision; information theory). The eye receives all sorts of irrelevant stimuli, which are mainly disregarded, just as unwanted data and random disturbances are rejected whenever possible by scientific instruments, and in computer signal-processing. Sometimes, though, what is rejected turns out to be just what is needed. The immense difficulties encountered in current attempts to program computers to recognize objects from signals provided by television cameras indicate the incredible complexity and subtlety of animal and human perception (see object perception). A key, surely, is the vast knowledge needed for sophisticated perception; but as yet this is inadequate, and hard to access as needed, in computers (see artificial intelligence).
David Marr (1980) suggested that object shapes are derived from images via three essential stages: (i) the 'primal sketch'(es), describing intensity changes, locations of critical features such as terminal points, and local geometrical relations; (ii) the '2½-D sketch', giving a preliminary analysis of depth, surface discontinuities, and so on, in a frame that is centred on the viewer; (iii) the '3-D model representation', in an object-centred coordinate system, so that we see objects much as they are in three-dimensional space though they are presented from just one viewpoint. Marr supposed that this last stage is aided by restraints on the range of likely solutions to the problem of what is 'out there', the information-processing restraints being set by assuming typical object shapes, for example that many objects such as human beings, are modified cylinders, spheres, and cones. Interestingly, the painter Paul Cezanne came close to this notion in 1904: 'Treat nature by the cylinder, the sphere, the cone, everything in proper perspective so that each side of an object or a plane is directed towards a central point ... nature for us men is more depth than surface'.
The limited variety of typical objects may set restraints that are useful both for brains for perceiving, and for the artist to represent objects, and for the artificial intelligence endeavour to program computers to see. But although it can be difficult to represent or see some atypical objects (or even familiar objects from atypical viewpoints), perhaps it is not clear that these difficulties reflect perceptual restraints based on assuming cylinders, spheres, or cones, etc., for very different shapes can generally be seen without special difficulty.
Looking 'inwards' by introspection, we seem to know that perceptions are made of sensations, although from physiological and psychological experiments, as well as from the engineering approach, it has to be denied that sensations are the data for perceptions. The data are neural signals, from the transducer senses, transmitted by many parallel channels — we may say to generate predictive hypotheses, which are our perceptual reality of the object world (see perceptions as unconscious influences).
It was generally thought that perception occurs passively from inputs from the senses. It is now, however, generally accepted that stored knowledge and assumptions actively affect even the simplest perceptions. The relative importance of what are called passive 'bottom-up' processes to active 'top-down' processes, is a central controversy among those who study perception. There is more and more evidence for top-down knowledge, carried to lower-level perceptual mechanisms, some of this evidence being physiological. Psychological evidence, bearing on this, is discussed in the entry on illusions. The changes of shape of wire cubes which reverse spontaneously in depth (see Necker cubes) is clear evidence of top-down processes affecting what used to be regarded as simple sensory characteristics, such as shape and brightness. This is an example of how illusory phenomena can reveal processes of perception far removed from the world we perceive. Yet the brain is a physical system, the most wonderful machine we know.
(Published 1987)
Just how we know things through sensory experience is a question that was discussed by the Greek philosophers and has continued to be discussed ever since. But, perhaps curiously, planned experiments in the spirit of the physical sciences were hardly attempted much earlier than the mid-19th century. Since then, the experimental study of perception has yielded fundamental knowledge for physiology and psychology, especially from the outstanding work of Hermann von Helmholtz (1867). It has revealed many surprises in the form of processes of which we are unaware, though they can often be demonstrated simply and dramatically as by the phenomena of illusions. The study of perception, especially of vision and hearing and touch, has allowed psychology to grow from its philosophical roots into an experimental science; yet deeply puzzling philosophical questions remain, especially over the role of consciousness. It is puzzling, both that we are aware of so little of perception, and that we have any awareness or consciousness.
There is a long-standing tradition in philosophy that perception gives undeniably true knowledge. Philosophers have traditionally sought certainty, and often claimed it, whereas scientists — who are used to their theories being modified and upset by new data — generally settle for today's best bet. Philosophers have a heavy investment in the reliability of perception, for they stake their all on the certainty of knowledge from the senses to provide secure premisses for their arguments based on experience. Scientists, on the other hand, who are used to errors in measurement and observations, have found it necessary to check, and compare, and repeat observations as they do not expect reliability from the senses. Indeed, many scientific instruments have been developed precisely because of the limitations or the unreliability of perception: for it is easy to produce and demonstrate all manner of dramatic illusions, which could hardly occur if perception were direct reliable knowledge. Yet although illusions of object perception have been discussed by philosophers from Aristotle to Berkeley and more recently, philosophy generally has paid more attention to errors of logic and ambiguity of language, than to fallibilities of perception.
Philosophers are traditionally impressed by the undeniability of the 'raw experience' of sensations. The sensation of toothache may be undeniable; but are perceptions of objects, and things happening, similarly infallible? One would think so if one believed that perceptions are simply sensations; but we now regard perceptions as giving us knowledge, albeit surprisingly indirectly, of the causes or sources of sensations — such as the states of our bodies, and especially objects in the environment — rather than of sensations themselves. It is now clear that there are vast, still largely mysterious perceptual jumps, intelligent leaps of the mind, which may land on error. One can, indeed, be wrong about the cause of toothache!
It is worth asking why we have both perceptions and conceptions of the world. Why is perception somehow separate, and in several ways different from our conceptual understanding? Very likely it is because perception, in order to be useful, must work very fast; whereas we may take minutes, hours, or years, forming concepts.
Perception is not traditionally thought of as an intelligent activity, though the power, especially of vision, to probe distance gains time needed for intelligent reactions to on-going events. It can be argued (see stimulus) that the development of distance perception freed organisms from the tyranny of reflexes, and allowed perception to be intelligent.
Are perceptions picked up by the senses, or are they created internally by the perceiver? This question about the passivity or activity of perception is long-standing, and still debated. If sensations are created by the brain, a notion that receives strong support from physiology (see visual brain in action; visual system: environmental influences; visual system: organization), we should expect to find, as we do, a vast amount of brain activity for perception. Whereas, if perceptions are simply 'picked up' (Gibson 1950, 1966), the brain would have little to do. But a very great deal goes on, physiologically and cognitively.
This raises the old question: what is 'objective' and what is 'subjective'? The philosopher John Locke (1690), who was well aware of the new science of his time, suggested that there are two kinds of characteristics: primary characteristics, such as hardness, mass, and extension of objects in space and time — being in the world before life, and quite apart from mind — and secondary characteristics, which are created by brain–mind. Thus colours are not in the world, but are created within us, though they are related in complex ways to light and the surfaces of objects.
It is generally accepted that Locke's 'primary' characteristics are present independently of mind and perception, and it is clear that 'secondary' characteristics are affected by states of the sensing organism; because colours change with adaptation, and everything appears tinged with yellow if we have jaundice. Isaac Newton, writing on sensations of colour in Opticks (1704), agreed with his friend Locke, saying that red light is not itself red, but is 'red-making'. Spelling this out, he said of light rays: 'there is nothing else than a certain power and disposition to stir up the sensation of this or that colour. For as sound in a bell or musical string ... is nothing but a trembling motion.' Then (in Query 23), he specifies something of the neural mechanism of vision that leads to the mysterious seat of sensation: 'Is not vision perform'd chiefly by the Vibrations of this (Eatherial) Medium, excited in the bottom of the eye by Rays of Light, and propagated through the solid, pellucid and uniform Capillamenta of the optic Nerves in the place (the "Sensorium") of Sensation?'
The empiricist school, of which Locke and Newton were founders, rejected the notion that had been the basis of much philosophy, that minds can receive knowledge by direct intuition, quite apart from perception. Mind was now regarded as essentially isolated from the physical world, linked by tenuous threads of nerve, sending signals to the brain, which has to make sense of sensations. At the same time, there were attempts to discover 'laws' of mind, corresponding in some ways to the laws of physics, though seldom if ever seen as being in quite the same category. Newton did, however, write (in a letter to Henry Oldenburg, secretary of the Royal Society): 'I suppose the Science of colours will be granted Mathematicall and as certain as any part of Optiques'. Laws of colour mixture were developed later, especially following the work of Thomas Young, who made the important discovery in 1801 that all the spectral colours can be produced by mixture of various intensities of only three spectral lights. This took the sensations of colour somewhat outside the realm of physics, and yet they were seen as bound by certain laws. So evidently there could be a lawful science of sensation and of mind (see colour vision: brain mechanisms; colour vision: eye mechanisms). Newton fully appreciated that colour sensations are not always given by light, as he said (Opticks, Query 16): 'When a Man in the dark presses either corner of his Eye with his finger, he will see a Circle of Colours like those of a Peacock's Tail.' At the same time, much like Pythagoras linking music with the physics of vibrating strings, Newton tried to describe aesthetics according to physical principles (Query 14):
- May not the harmony and discord of Colours arise from the proportions of the Vibrations propagated through the Fibres of the optick Nerves into the Brain, as the harmony and discord of Sounds arise from the proportions of the Vibrations of the Air? For some Colours, if they are view'd together, are agreeablezto one another, as those of Gold and Indigo, and others disagree.
It is now generally accepted that perception depends on active physiologically based processes; but this notion is non-intuitive, for we know nothing of such processes or mechanisms by introspection, by consciousness. Moreover, perceiving objects around us seems so simple and easy! It happens so fast, and so effortlessly it is hard to conceive the complexity of the processes that we now know are involved.
This takes us to concepts familiar to engineers. It is not misleading to describe the organs of the senses — the eyes, ears, touch receptors, and so on — as 'transducers' that accept and signal patterns of energy from the external world, as coded messages, read by the brain to infer the state-of-play of the surrounding world. Another useful engineering concept is that of 'channels'. The various senses: touch and vision and hearing, and so on, are each subdivided into channels which generally can only be discovered by experiment. Thus, for example, though this was not at all realized before Young's (1801) colour mixture experiment, colour vision works with just three channels, responding to long-wavelength red, medium-wavelength green, and short-wavelength blue, light, respectively. All the hundreds of colours we see are, neurally, mixtures from these three colour channels (see yellow.) Then there are channels representing the orientation of lines and edges, and channels for movement, as shown by direct physiological recording from the visual cortex, demonstrated dramatically by David Hubel and Torstin Wiesel (1962), who received the Nobel Prize for this outstanding work. By less physiologically direct methods, such as selective adaptation, it has been found that there are more or less independent channels for spatial frequency and many other visual characteristics. The ear has many frequency channels (see hearing), and there is a score of channels for touch, various kinds of pain, tickle, and for monitoring the positions of the limbs and setting muscle tensions for moving them appropriately (see pain; tickling). Small discrepancies, such as delay in sound between seeing a ball hit by a bat and hearing the impact, are rejected or pulled into place, to maintain a consistent world. Here, the constancies (see colour perception: constancy and contrast) are very important; they modify sensations and perceptions to fit what should be there!
For signalling by the senses, as from instruments, it is important to appreciate the range of likely or possible objects that may be present (see information rate of vision; information theory). The eye receives all sorts of irrelevant stimuli, which are mainly disregarded, just as unwanted data and random disturbances are rejected whenever possible by scientific instruments, and in computer signal-processing. Sometimes, though, what is rejected turns out to be just what is needed. The immense difficulties encountered in current attempts to program computers to recognize objects from signals provided by television cameras indicate the incredible complexity and subtlety of animal and human perception (see object perception). A key, surely, is the vast knowledge needed for sophisticated perception; but as yet this is inadequate, and hard to access as needed, in computers (see artificial intelligence).
David Marr (1980) suggested that object shapes are derived from images via three essential stages: (i) the 'primal sketch'(es), describing intensity changes, locations of critical features such as terminal points, and local geometrical relations; (ii) the '2½-D sketch', giving a preliminary analysis of depth, surface discontinuities, and so on, in a frame that is centred on the viewer; (iii) the '3-D model representation', in an object-centred coordinate system, so that we see objects much as they are in three-dimensional space though they are presented from just one viewpoint. Marr supposed that this last stage is aided by restraints on the range of likely solutions to the problem of what is 'out there', the information-processing restraints being set by assuming typical object shapes, for example that many objects such as human beings, are modified cylinders, spheres, and cones. Interestingly, the painter Paul Cezanne came close to this notion in 1904: 'Treat nature by the cylinder, the sphere, the cone, everything in proper perspective so that each side of an object or a plane is directed towards a central point ... nature for us men is more depth than surface'.
The limited variety of typical objects may set restraints that are useful both for brains for perceiving, and for the artist to represent objects, and for the artificial intelligence endeavour to program computers to see. But although it can be difficult to represent or see some atypical objects (or even familiar objects from atypical viewpoints), perhaps it is not clear that these difficulties reflect perceptual restraints based on assuming cylinders, spheres, or cones, etc., for very different shapes can generally be seen without special difficulty.
Looking 'inwards' by introspection, we seem to know that perceptions are made of sensations, although from physiological and psychological experiments, as well as from the engineering approach, it has to be denied that sensations are the data for perceptions. The data are neural signals, from the transducer senses, transmitted by many parallel channels — we may say to generate predictive hypotheses, which are our perceptual reality of the object world (see perceptions as unconscious influences).
It was generally thought that perception occurs passively from inputs from the senses. It is now, however, generally accepted that stored knowledge and assumptions actively affect even the simplest perceptions. The relative importance of what are called passive 'bottom-up' processes to active 'top-down' processes, is a central controversy among those who study perception. There is more and more evidence for top-down knowledge, carried to lower-level perceptual mechanisms, some of this evidence being physiological. Psychological evidence, bearing on this, is discussed in the entry on illusions. The changes of shape of wire cubes which reverse spontaneously in depth (see Necker cubes) is clear evidence of top-down processes affecting what used to be regarded as simple sensory characteristics, such as shape and brightness. This is an example of how illusory phenomena can reveal processes of perception far removed from the world we perceive. Yet the brain is a physical system, the most wonderful machine we know.
(Published 1987)
— Richard L. Gregory
- Bibliography
- Cezanne, P. (1904). Letter from Aix-en-Provence. In Rewald, J. (ed.) (1941), Letters, and in Goldwater, R., and Treves, M. (eds.) (1976). Artists on Art.
- Gibson, J. J. (1950). Perception of the Visual World.
- — — (1966). The Senses Considered as Perceptual Systems.
- Gombrich, E. (1960). Art and Illusion.
- Gregory, R. L. (1966, 5th edn. 1997). Eye and Brain.
- Helmholtz, H. von (1867). Handbuch der Physiologischen Optic. Hamburg. (3rd edn. 1909; trans. 1924 by Southall, J. P. C., with additions, as Helmholtz's Treatise on Physiological Optics, repr. 1962).
- Hubel, D. H., and Wiesel, T. N. (1962). 'Receptive field, binocular interaction and functional architecture in the cat's visual cortex'. Journal of Physiology, 160.
- Locke, J. (1690). Essay Concerning Human Understanding.
- Marr, D. (1982). Vision: A Computational Investigation into the Human Representation and Processing of Visual Information.
- Newton, I. (1704). Opticks. (4th edn. 1730).
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perception
IN BRIEF: Knowledge through the senses of the existence and properties of matter or the external world.
Possession diminishes perception of value, immediately.
— John Updike
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Perception
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"Perception is a mirror not a fact. And what I look on is my state of mind, reflected outward."
- A Course In Miracles
"To perceive means to immobilize... we seize, in the act of perception, something which outruns perception itself."
- Henri L. Bergson
"If the doors of perception were cleansed everything would appear to man as it is, infinite. For man has closed himself up, till he sees all things thru chinks of his cavern."
- William Blake
"Nothing exists until or unless it is observed. An artist is making something exist by observing it. And his hope for other people is that they will also make it exist by observing it. I call it creative observation. Creative viewing."
- William S. Burroughs
"You are only as wise as others perceive you to be."
- M. Shawn Cole
"To see what is right, and not do it, is want of courage, or of principle."
- Confucius
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Perception
The process of becoming aware of a stimulus. Perception is the interpretation of a sensation.
Saunders Veterinary Dictionary:
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perception
The conscious mental registration of a sensory stimulus. The ability of animals to perceive is apparent from their responses to the application of stimuli but the nature of the perceptivity is only surmised. The difficulty in examining an animal is to decide whether a failure to respond to a stimulus is due to lack of perception, inability to respond or disinclination to do so.
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categories related to 'perception'
- Mental States, Processes, and Behavior - perception: process of conscious sensory input; cognition
- Reason and Rationale - perception: capacity for comprehension; keen mental faculty or observation
- Intuition and Imagination - perception: awareness of one’s environment, esp. recognition by intuition or senses
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Perception
For other uses, see Perception (disambiguation).
"Percept" redirects here. For other uses, see Percept (disambiguation).
"Perceptual" redirects here. For the Brian Blade album, see Perceptual (album).
"Perceptible" and "imperceptible" redirect here. For perceptibility of digital watermarks, see Digital watermarking#Perceptibility.
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Perception (from the Latin perceptio, percipio) is the organization, identification, and interpretation of sensory information in order to fabricate a mental representation through the process of transduction, which sensors in the body transform signals from the environment into encoded neural signals.[1] All perception involves signals in the nervous system, which in turn result from physical stimulation of the sense organs.[2] For example, vision involves light striking the retinas of the eyes, smell is mediated by odor molecules and hearing involves pressure waves. Perception is not the passive receipt of these signals, but can be shaped by learning, memory and expectation.[3][4] Perception involves these "top-down" effects as well as the "bottom-up" process of processing sensory input.[4] The "bottom-up" processing is basically low-level information that's used to build up higher-level information (i.e. - shapes for object recognition). The "top-down" processing refers to a person's concept and expectations (knowledge) that influence perception. Perception depends on complex functions of the nervous system, but subjectively seems mostly effortless because this processing happens outside conscious awareness.[2]
Since the rise of experimental psychology in the late 19th Century, psychology's understanding of perception has progressed by combining a variety of techniques.[3] Psychophysics measures the effect on perception of varying the physical qualities of the input. Sensory neuroscience studies the brain mechanisms underlying perception. Perceptual systems can also be studied computationally, in terms of the information they process. Perceptual issues in philosophy include the extent to which sensory qualities such as sounds, smells or colors exist in objective reality rather than the mind of the perceiver.[3]
Although the senses were traditionally viewed as passive receptors, the study of illusions and ambiguous images has demonstrated that the brain's perceptual systems actively and pre-consciously attempt to make sense of their input.[3] There is still active debate about the extent to which perception is an active process of hypothesis testing, analogous to science, or whether realistic sensory information is rich enough to make this process unnecessary.[3]
The perceptual systems of the brain enable individuals to see the world around them as stable, even though the sensory information may be incomplete and rapidly varying. Human and animal brains are structured in a modular way, with different areas processing different kinds of sensory information. Some of these modules take the form of sensory maps, mapping some aspect of the world across part of the brain's surface. These different modules are interconnected and influence each other. For instance, the taste is strongly influenced by its odor.[5]
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Process and terminology
The process of perception begins with an object in the real world, termed the distal stimulus or distal object.[2] By means of light, sound or another physical process, the object stimulates the body's sensory organs. These sensory organs transform the input energy into neural activity—a process called transduction.[6][2] This raw pattern of neural activity is called the proximal stimulus.[2] These neural signals are transmitted to the brain and processed.[2] The resulting mental recreation of the distal stimulus is the percept. Perception is sometimes described as the process of constructing mental representations of distal stimuli using the information available in proximal stimuli.
An example would be a person looking at a shoe. The shoe itself is the distal stimulus. When light from the shoe enters a person's eye and stimulates their retina, that stimulation is the proximal stimulus.[7] The image of the shoe reconstructed by the brain of the person is the percept. Another example would be a telephone ringing. The ringing of the telephone is the distal stimulus. The sound stimulating a person's auditory receptors is the proximal stimulus, and the brain's interpretation of this as the ringing of a telephone is the percept. The different kinds of sensation such as warmth, sound, and taste are called "sensory modalities".[6][8]
Psychologist Jerome Bruner has developed a model of perception. According to him people go through the following process to form opinions:.[9]
- When a perceiver encounters an unfamiliar target we are opened different informational cues and want to learn more about the target.
- In the second step we try to collect more information about the target. Gradually, we encounter some familiar cues which helps us categorize the target.
- At this stage the cues become less open and selective. We try to search for more cues that confirm the categorization of the target. At this stage we also actively ignore and even distort cues that violate our initial perceptions. Our perception becomes more selective and we finally paint a consistent picture of the target.
According to Alan Saks and Gary Johns, there are three components to Perception.[9]
- The Perceiver, the person who becomes aware about something and comes to a final understanding. There are 3 factors that can influence his or her perceptions: experience, motivational state and finally emotional state. In different motivational or emotional states, the perceiver will react to or perceive something in different ways. Also in different situations he or she might employ a "perceptual defence" where they tend to "see what they want to see".
- The Target. This is the person who is being perceived or judged. "Ambiguity or lack of information about a target leads to a greater need for interpretation and addition."
- The Situation also greatly influences perceptions because different situations may call for additional information about the target.
Stimuli are not necessarily translated into a percept and rarely does a single stimulus translate into a percept. An ambiguous stimulus may be translated into multiple percepts, experienced randomly, one at a time, in what is called "multistable perception". And the same stimuli, or absence of them, may result in different percepts depending on subject’s culture and previous experiences. Ambiguous figures demonstrate that a single stimulus can result in more than one percept; for example the Rubin vase which can be interpreted either as a vase or as two faces. The percept can bind sensations from multiple senses into a whole. A picture of a talking person on a television screen, for example, is bound to the sound of speech from speakers to form a percept of a talking person. "Percept" is also a term used by Leibniz,[10] Bergson, Deleuze and Guattari[11] to define perception independent from perceivers.
Perception and reality
In the case of visual perception, some people can actually see the percept shift in their mind's eye.[12] 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.
This confusing ambiguity of perception is exploited in human technologies such as camouflage, and also in biological mimicry, for example by European Peacock butterflies, whose wings bear eye markings that birds respond to as though they were the eyes of a dangerous predator.
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.[13]
Perception is one of the oldest fields in psychology. The oldest quantitative law in psychology is the Weber-Fechner law, which quantifies the relationship between the intensity of physical stimuli and their perceptual effects (for example, testing how much darker a computer screen can get before the viewer actually notices). The study of perception gave rise to the Gestalt school of psychology, with its emphasis on holistic approach.
Features
Constancy
Main article: Subjective constancy
Perceptual constancy is the ability of perceptual systems to recognise the same object from widely varying sensory inputs.[4][14] For example, individual people can be recognised from views, such as frontal and profile, which form very different shapes on the retina. A coin looked at face-on makes a circular image on the retina, but when held at angle it makes an elliptical image.[15] In normal perception these are recognised as a single three-dimensional object. Without this correction process, an animal approaching from the distance would appear to gain in size.[16][17] One kind of perceptual constancy is color constancy: for example, a white piece of paper can be recognised as such under different colors and intensities of light.[17] Another example is roughness constancy: when a hand is drawn quickly across a surface, the touch nerves are stimulated more intensely. The brain compensates for this, so the speed of contact does not affect the perceived roughness.[17] Other constancies include melody, odor, brightness and words.[18] These constancies are not always total, but the variation in the percept is much less than the variation in the physical stimulus.[17] The perceptual systems of the brain achieve perceptual constancy in a variety of ways, each specialized for the kind of information being processed.[19]
Grouping
Main article: Principles of grouping
The principles of grouping (or Gestalt laws of grouping) are a set of principles in psychology, first proposed by Gestalt psychologists to explain how humans naturally perceive objects as organized patterns and objects. Gestalt psychologists argued that these principles exist because the mind has an innate disposition to perceive patterns in the stimulus based on certain rules. These principles are organized into six categories. The principle of proximity states that, all else being equal, perception tends to group stimuli that are close together as part of the same object, and stimuli that are far apart as two separate objects. The principle of similarity states that, all else being equal, perception lends itself to seeing stimuli that physically resemble each other as part of the same object, and stimuli that are different as part of a different object. This allows for people to distinguish between adjacent and overlapping objects based on their visual texture and resemblance. The principle of closure refers to the mind’s tendency to see complete figures or forms even if a picture is incomplete, partially hidden by other objects, or if part of the information needed to make a complete picture in our minds is missing. For example, if part of a shape’s border is missing people still tend to see the shape as completely enclosed by the border and ignore the gaps. The principle of good continuation makes sense of stimuli that overlap: when there is an intersection between two or more objects, people tend to perceive each as a single uninterrupted object. The principle of common fate groups stimuli together on the basis of their movement. When visual elements are seen moving in the same direction at the same rate, perception associates the movement as part of the same stimulus. This allows people to make out moving objects even when other details, such as color or outline, are obscured. The principle of good form refers to the tendency to group together forms of similar shape, pattern, color, etc.[20][21][22][23] Later research has identified additional grouping principles.[24]
Contrast effects
Main article: Contrast effect
A common finding across many different kinds of perception is that the perceived qualities of an object can be affected by the qualities of context. If one object is extreme on some dimension, then neighboring objects are perceived as further away from that extreme. "Simultaneous contrast effect" is the term used when stimuli are presented at the same time, whereas "successive contrast" applies when stimuli are presented one after another.[25]
The contrast effect was noted by the 17th Century philosopher John Locke, who observed that lukewarm water can feel hot or cold, depending on whether the hand touching it was previously in hot or cold water.[26] In the early 20th Century, Wilhelm Wundt identified contrast as a fundamental principle of perception, and since then the effect has been confirmed in many different areas.[26] These effects shape not only visual qualities like color and brightness, but other kinds of perception, including how heavy an object feels.[27] One experiment found that thinking of the name "Hitler" led to subjects rating a person as more hostile.[28] Whether a piece of music is perceived as good or bad can depend on whether the music heard before it was unpleasant or pleasant.[29] For the effect to work, the objects being compared need to be similar to each other: a television reporter can seem smaller when interviewing a tall basketball player, but not when standing next to a tall building.[27]
Effect of experience
Main article: Perceptual learning
With experience, organisms can learn to make finer perceptual distinctions, and learn new kinds of categorization. Wine-tasting, the reading of X-ray images and music appreciation are applications of this process in the human sphere. Research has focused on the relation of this to other kinds of learning, and whether it takes place in peripheral sensory systems or in the brain's processing of sense information.[citation needed]
Effect of motivation and expectation
Main article: Set (psychology)
A perceptual set, also called perceptual expectancy or just set is a predisposition to perceive things in a certain way.[30] It is an example of how perception can be shaped by "top-down" processes such as drives and expectations.[31] Perceptual sets occur in all the different senses.[16] They can be long term, such as a special sensitivity to hearing one's own name in a crowded room, or short term, as in the ease with which hungry people notice the smell of food.[32] A simple demonstration of the effect involved very brief presentations of non-words such as "sael". Subjects who were told to expect words about animals read it as "seal", but others who were expecting boat-related words read it as "sail".[32]
Sets can be created by motivation and so can result in people interpreting ambiguous figures so that they see what they want to see.[31] For instance, how someone perceives what unfolds during a sports game can be biased if they strongly support one of the teams.[33] In one experiment, students were allocated to pleasant or unpleasant tasks by a computer. They were told that either a number or a letter would flash on the screen to say whether they were going to taste an orange juice drink or an unpleasant-tasting health drink. In fact, an ambiguous figure was flashed on screen, which could either be read as the letter B or the number 13. When the letters were associated with the pleasant task, subjects were more likely to perceive a letter B, and when letters were associated with the unpleasant task they tended to perceive a number 13.[30]
Perceptual set has been demonstrated in many social contexts. People who are primed to think of someone as "warm" are more likely to perceive a variety of positive characteristics in them, than if the word "warm" is replaced by "cold". When someone has a reputation for being funny, an audience are more likely to find them amusing.[32] Individual's perceptual sets reflect their own personality traits. For example, people with an aggressive personality are quicker to correctly identify aggressive words or situations.[32]
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).[34]
Philosopher Andy Clark explains that perception, although it occurs quickly, is not simply a bottom-up process (where minute details are put together to form larger wholes). Instead, our brains use what he calls Predictive coding. It starts with very broad constraints and expectations for the state of the world, and as expectations are met, it makes more detailed predictions (errors lead to new predictions, or learning processes). Clark says this research has various implications; not only can there be no completely "unbiased, unfiltered" perception, but this means that there is a great deal of feedback between perception and expectation (perceptual experiences often shape our beliefs, but those perceptions were based on existing beliefs).[35]
Theories
Perception as hypothesis-testing
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. His theory "assumes the existence of stable, unbounded, and permanent stimulus-information in the ambient optic array. And it supposes that the visual system can explore and detect this information. The theory is information-based, not sensation-based."[36] He and the psychologists who work within this paradigm detailed how the world could be specified to a mobile, exploring organism via the lawful projection of information about the world into energy arrays.[citation needed] 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.[citation needed]
Perception-in-action
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 constructivism (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.[37]
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.[38]
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.
Evolutionary psychology and perception
Many experts, such as Jerry Fodor, write that the purpose of perception is knowledge, but evolutionary psychologists hold that its primary purpose is to guide action.[39] For example, they say, depth perception seems to have evolved not to help us know the distances to other objects but rather to help us move around in space.[39] Evolutionary psychologists say that animals from fiddler crabs to humans use eyesight for collision avoidance, suggesting that vision is basically for directing action, not providing knowledge.[39]
Building and maintaining sense organs is metabolically expensive, so these organs evolve only when they improve an organism's fitness.[39] More than half the brain is devoted to processing sensory information, and the brain itself consumes roughly one-fourth of one's metabolic resources, so the senses must provide exceptional benefits to fitness.[39] Perception accurately mirrors the world; animals get useful, accurate information through their senses.[39]
Scientists who study perception and sensation have long understood the human senses as adaptations.[39] Depth perception consists of processing over half a dozen visual cues, each of which is based on a regularity of the physical world.[39] Vision evolved to respond to the narrow range of electromagnetic energy that is plentiful and that does not pass through objects.[39] Sound waves provide useful information about the sources of and distances to objects, with larger animals making and hearing lower-frequency sounds and smaller animals making and hearing higher-frequency sounds.[39] Taste and smell respond to chemicals in the environment that were significant for fitness in the EEA.[39] The sense of touch is actually many senses, including pressure, heat, cold, tickle, and pain.[39] Pain, while unpleasant, is adaptive.[39] An important adaptation for senses is range shifting, by which the organism becomes temporarily more or less sensitive to sensation.[39] For example, one's eyes automatically adjust to dim or bright ambient light.[39] Sensory abilities of different organisms often coevolve, as is the case with the hearing of echolocating bats and that of the moths that have evolved to respond to the sounds that the bats make.[39]
Evolutionary psychologists claim that perception demonstrates the principle of modularity, with specialized mechanisms handling particular perception tasks.[39] For example, people with damage to a particular part of the brain suffer from the specific defect of not being able to recognize faces (prospagnosia).[39] EP suggests that this indicates a so-called face-reading module.[39]
Theories of visual perception
- Empirical theories of perception
- Anne Treisman's Feature Integration Theory
- Interactive Activation and Competition
- Irving Biederman's Recognition by Components Theory
Physiology
Main article: Sensory system
A sensory system is a part of the nervous system responsible for processing sensory information. A sensory system consists of sensory receptors, neural pathways, and parts of the brain involved in sensory perception. Commonly recognized sensory systems are those for vision, hearing, somatic sensation (touch), taste and olfaction (smell). It has been suggested that the immune system is an overlooked sensory modlality.[40] In short, senses are transducers from the physical world to the realm of the mind.
The receptive field is the specific part of the world to which a receptor organ and receptor cells respond. For instance, the part of the world an eye can see, is its receptive field; the light that each rod or cone can see, is its receptive field.[41] Receptive fields have been identified for the visual system, auditory system and somatosensory system, so far.
Types
Of sound
Main article: Hearing (sense)
Hearing (or audition) is the ability to perceive sound by detecting vibrations. Frequencies capable of being heard by humans are called audio or sonic. The range is typically considered to be between 20 Hz and 20,000 Hz.[42] Frequencies higher than audio are referred to as ultrasonic, while frequencies below audio are referred to as infrasonic. The auditory system includes the ears and inner structures which produce neural signals in response to the sound. The primary auditory cortex, within the temporal lobe of the human brain, is where auditory information arrives in the cerebral cortex.
Sound does not usually come from a single source: in real situations, sounds from multiple sources and directions are superimposed as they arrive at the ears. Hearing involves the computationally complex task of separating out the sources of interest, often estimating their distance and direction as well as identifying them.[15]
Of speech
Main article: Speech perception
Speech perception is the process by which the sounds of language are heard, interpreted and understood. Research in speech perception seeks to understand how human listeners recognize speech sounds and use this information to understand spoken language. The sound of a word can vary widely according to words around it and the tempo of the speech, as well as the physical characteristics, accent and mood of the speaker. Listeners manage to perceive words across this wide range of different conditions.[citation needed] Another variation is that reverberation can make a large difference in sound between a word spoken from the far side of a room and the same word spoken up close. Experiments have shown that people automatically compensate for this effect when hearing speech.[15][43]
The process of perceiving speech begins at the level of the sound within the auditory signal and the process of audition. After processing the initial auditory signal, speech sounds are further processed to extract acoustic cues and phonetic information. This speech information can then be used for higher-level language processes, such as word recognition. Speech perception is not necessarily uni-directional. That is, higher-level language processes connected with morphology, syntax, or semantics may interact with basic speech perception processes to aid in recognition of speech sounds.[citation needed] It may be the case that it is not necessary and maybe even not possible for a listener to recognize phonemes before recognizing higher units, like words for example. In one experiment, Richard M. Warren replaced one phoneme of a word with a cough-like sound. His subjects restored the missing speech sound perceptually without any difficulty and what is more, they were not able to identify accurately which phoneme had been disturbed.[44]
Touch
Main article: Haptic perception
Haptic perception is the process of recognizing objects through touch. It involves a combination of somatosensory perception of patterns on the skin surface (e.g., edges, curvature, and texture) and proprioception of hand position and conformation. People can rapidly and accurately identify three-dimensional objects by touch.[45] This involves exploratory procedures, such as moving the fingers over the outer surface of the object or holding the entire object in the hand.[46] Haptic perception relies on the forces experienced during touch.[47]
Gibson defined the haptic system as "The sensibility of the individual to the world adjacent to his body by use of his body".[48] Gibson and others emphasized the close link between haptic perception and body movement: haptic perception is active exploration. The concept of haptic perception is related to the concept of extended physiological proprioception according to which, when using a tool such as a stick, perceptual experience is transparently transferred to the end of the tool.
Taste
Main article: Taste
Taste (or, the more formal term, gustation) is the ability to perceive the flavor of substances including, but not limited to, food. Humans receive tastes through sensory organs called taste buds, or gustatory calyculi, concentrated on the upper surface of the tongue.[49] The human tongue has 100 to 150 taste receptor cells on each of its roughly ten thousand taste buds.[50] There are five primary tastes: sweetness, bitterness, sourness, saltiness, and umami. Other tastes can be mimicked by combining these basic tastes.[50][51] The recognition and awareness of umami is a relatively recent development in Western cuisine.[52] The basic tastes contribute only partially to the sensation and flavor of food in the mouth — other factors include smell, detected by the olfactory epithelium of the nose;[5] texture, detected through a variety of mechanoreceptors, muscle nerves, etc.;[51][53] and temperature, detected by thermoreceptors.[51] All basic tastes are classified as either appetitive or aversive, depending upon whether the things they sense are harmful or beneficial.[54]
Of the social world
Main article: Social perception
Social perception is the part of perception that allows people to understand the individuals and groups of their social world, and thus an element of social cognition.[55]
See also
|
Notes
- ^ Schacter, Daniel (2011). Psychology. Worth Publishers.
- ^ a b c d e f Goldstein (2009) pp. 5–7
- ^ a b c d e Gregory, Richard. "Perception" in Gregory, Zangwill (1987) pp. 598–601
- ^ a b c Bernstein, Douglas A. (5 March 2010). Essentials of Psychology. Cengage Learning. pp. 123–124. ISBN 978-0-495-90693-3. http://books.google.com/books?id=rd77N0KsLVkC&pg=PA123. Retrieved 25 March 2011.
- ^ a b DeVere, Ronald; Calvert, Marjorie (31 August 2010). Navigating Smell and Taste Disorders. Demos Medical Publishing. pp. 33–37. ISBN 978-1-932603-96-5. http://books.google.com/books?id=m6WOtX2QAtwC&pg=PA39. Retrieved 26 March 2011.
- ^ a b Pomerantz, James R. (2003): "Perception: Overview". In: Lynn Nadel (Ed.), Encyclopedia of Cognitive Science, Vol. 3, London: Nature Publishing Group, pp. 527–537
- ^ http://www.learner.org/discoveringpsychology/07/e07glossary.html
- ^ Willis, William D.; Coggeshall, Richard E. (31 January 2004). Sensory Mechanisms of the Spinal Cord: Primary afferent neurons and the spinal dorsal horn. Springer. p. 1. ISBN 978-0-306-48033-1. http://books.google.com/books?id=uqnKCewO2voC&pg=PA1. Retrieved 25 March 2011.
- ^ a b Alan S. & Gary J. (2011). Perception, Attribution, and Judgment of Others. Organizational Behaviour: Understanding and Managing Life at Work Vol. 7
- ^ Leibniz' Monadology
- ^ Deleuze and Guattari's What is Philosophy?
- ^ Wettlaufer, Alexandra K. (2003). In the mind's eye : the visual impulse in Diderot, Baudelaire and Ruskin, pg. 257. Amsterdam: Rodopi. ISBN 90-420-1035-5
- ^ The Secret Advantage Of Being Short by Robert Krulwich. All Things Considered, NPR. 18 May 2009.
- ^ Atkinson, Rita L.; Atkinson, Richard C.; Smith, Edward E. (March 1990). Introduction to psychology. Harcourt Brace Jovanovich. pp. 177–183. ISBN 978-0-15-543689-3. http://books.google.com/books?id=Nw54PwAACAAJ. Retrieved 24 March 2011.
- ^ a b c Moore, Brian C. J. (15 October 2009). "Audition". In Goldstein, E. Bruce. Encyclopedia of Perception. Sage. pp. 136–137. ISBN 978-1-4129-4081-8. http://books.google.com/books?id=Y4TOEN4f5ZMC&pg=PA136. Retrieved 26 March 2011.
- ^ a b Sonderegger, Theo (16 October 1998). Psychology. John Wiley and Sons. pp. 45–46. ISBN 978-0-8220-5327-9. http://books.google.com/books?id=UUrCHiSb_QsC&pg=PA45. Retrieved 24 March 2011.
- ^ a b c d Goldstein, E. Bruce (15 October 2009). "Constancy". In E. Bruce Goldstein. Encyclopedia of Perception. Sage. pp. 309–313. ISBN 978-1-4129-4081-8. http://books.google.com/books?id=Y4TOEN4f5ZMC&pg=PA309. Retrieved 26 March 2011.
- ^ Roeckelein, Jon E. (2006). Elsevier's dictionary of psychological theories. Elsevier. p. 126. ISBN 978-0-444-51750-0. http://books.google.com/books?id=1Yn6NZgxvssC&pg=PA126. Retrieved 24 March 2011.
- ^ Yantis, Steven (2001). Visual perception: essential readings. Psychology Press. p. 7. ISBN 978-0-86377-598-7. http://books.google.com/books?id=GpGvYSTk9gYC&pg=PA7. Retrieved 24 March 2011.
- ^ Gray, Peter O. (2006): Psychology, 5th ed., New York: Worth, p. 281. ISBN 978-0-7167-0617-5
- ^ Wolfe, Jeremy M.; Kluender, Keith R.; Levi, Dennis M.; Bartoshuk, Linda M.; Herz, Rachel S.; Klatzky, Roberta L.; Lederman, Susan J. (2008). "Gestalt Grouping Principles". Sensation and Perception (2nd ed.). Sinauer Associates. pp. 78, 80. ISBN 978-0-87893-938-1. http://www.sinauer.com./wolfe/chap4/gestaltF.htm.
- ^ Goldstein (2009). pp. 105–107
- ^ Banerjee, J. C. (1994). "Gestalt Theory of Perception". Encyclopaedic Dictionary of Psychological Terms. M.D. Publications Pvt. Ltd. pp. 107–108. ISBN 978-81-85880-28-0.
- ^ Weiten, Wayne (1998). Psychology: themes and variations (4th ed.). Brooks/Cole Pub. Co.. p. 144. ISBN 978-0-534-34014-8.
- ^ Corsini, Raymond J. (2002). The dictionary of psychology. Psychology Press. p. 219. ISBN 978-1-58391-328-4. http://books.google.com/books?id=0uxnglHzYaoC&pg=PA219. Retrieved 24 March 2011.
- ^ a b Kushner, Laura H. (2008). Contrast in judgments of mental health. ProQuest. p. 1. ISBN 978-0-549-91314-6. http://books.google.com/books?id=TYn5VHp9jioC&pg=PA1. Retrieved 24 March 2011.
- ^ a b Plous, Scott (1993). The psychology of judgment and decision making. McGraw-Hill. pp. 38–41. ISBN 978-0-07-050477-6. http://books.google.com/books?id=xvWOQgAACAAJ. Retrieved 24 March 2011.
- ^ Moskowitz, Gordon B. (2005). Social cognition: understanding self and others. Guilford Press. p. 421. ISBN 978-1-59385-085-2. http://books.google.com/books?id=_-NLW8Ynvp8C&pg=PA421. Retrieved 24 March 2011.
- ^ Popper, Arthur N. (30 November 2010). Music Perception. Springer. p. 150. ISBN 978-1-4419-6113-6. http://books.google.com/books?id=ZYXd3CF1_vkC&pg=PA150. Retrieved 24 March 2011.
- ^ a b Weiten, Wayne (17 December 2008). Psychology: Themes and Variations. Cengage Learning. p. 193. ISBN 978-0-495-60197-5. http://books.google.com/books?id=sILajOhJpOsC&pg=PT193. Retrieved 24 March 2011.
- ^ a b Coon, Dennis; Mitterer, John O. (29 December 2008). Introduction to Psychology: Gateways to Mind and Behavior. Cengage Learning. pp. 171–172. ISBN 978-0-495-59911-1. http://books.google.com/books?id=vw20LEaJe10C&pg=PA171. Retrieved 24 March 2011.
- ^ a b c d Hardy, Malcolm; Heyes, Steve (2 December 1999). Beginning Psychology. Oxford University Press. pp. 24–27. ISBN 978-0-19-832821-6. http://books.google.com/books?id=fjPWqXi9WQsC&pg=PA24. Retrieved 24 March 2011.
- ^ Block, J. R.; Yuker, Harold E. (1 October 2002). Can You Believe Your Eyes?: Over 250 Illusions and Other Visual Oddities. Robson. pp. 173–174. ISBN 978-1-86105-586-6. http://books.google.com/books?id=uNMFiMQu8BMC&pg=PA173. Retrieved 24 March 2011.
- ^ "On the Perception of Incongruity: A Paradigm" by Jerome S. Bruner and Leo Postman. Journal of Personality, 18, pp. 206-223. 1949. Yorku.ca
- ^ http://www.edge.org/q2011/q11_6.html
- ^ Gibson, James J. (2002): "A Theory of Direct Visual Perception". In: Alva Noë/Evan Thompson (Eds.), Vision and Mind. Selected Readings in the Philosophy of Perception, Cambridge, MIT Press, pp. 77–89.
- ^ Consciousness in Action, S. L. Hurley, illustrated, Harvard University Press, 2002, 0674007964, pg. 430-432,
- ^ Glasersfeld, Ernst von (1995), Radical Constructivism: A Way of Knowing and Learning, London: RoutledgeFalmer; Poerksen, Bernhard (ed.) (2004), The Certainty of Uncertainty: Dialogues Introducing Constructivism, Exeter: Imprint Academic; Wright. Edmond (2005). Narrative, Perception, Language, and Faith, Basingstoke: Palgrave Macmillan.
- ^ a b c d e f g h i j k l m n o p q r s Gaulin, Steven J. C. and Donald H. McBurney. Evolutionary Psychology. Prentice Hall. 2003. ISBN 978-0-13-111529-3, Chapter 4, p 81-101.
- ^ Bedford,F.L. (2011). The missing sensory modality: the immune system. Perception, 40, 1265-1267 doi:10.1068/p7119 http://www.perceptionweb.com/abstract.cgi?id=p7119
- ^ Kolb & Whishaw: Fundamentals of Human Neuropsychology (2003)
- ^ "Frequency Range of Human Hearing". The Physics Factbook. http://hypertextbook.com/facts/2003/ChrisDAmbrose.shtml.
- ^ Watkins, Anthony J.; Raimond, Andrew; Makin, Simon J. (23 March 2010). "Room reflection and constancy in speech-like sounds: Within-band effects". In Enrique A. Lopez-Poveda. The Neurophysiological Bases of Auditory Perception. Springer. p. 440. ISBN 978-1-4419-5685-9. http://books.google.com/books?id=ACkNL-G7gUUC&pg=PA440. Retrieved 26 March 2011.
- ^ Warren, R.M. (1970). "Restoration of missing speech sounds". Science 167 (3917): 392–393. doi:10.1126/science.167.3917.392. PMID 5409744.
- ^ Klatzky RL, Lederman SJ, & Metzger VA (1985). "Identifying objects by touch: An "expert system."". Perception & Psychophysics 37 (37): 299–302. doi:10.3758/BF03211351.
- ^ Lederman SJ, & Klatzky RL (1987). "Hand movements: A window into haptic object recognition". Cognitive Psychology 19 (19): 342–368. doi:10.1016/0010-0285(87)90008-9.
- ^ Robles-de-la-torre, Gabriel; Hayward, Vincent (2001). "Force can overcome object geometry in the perception of shape through active touch". Nature 412 (6845): 445–448. doi:10.1038/35086588. PMID 11473320.
- ^ Gibson, J.J. (1966). The senses considered as perceptual systems.. Boston: Houghton Mifflin. ISBN 0-313-23961-4.
- ^ Human biology (Page 201/464) Daniel D. Chiras. Jones & Bartlett Learning, 2005.
- ^ a b DeVere, Ronald; Calvert, Marjorie (31 August 2010). Navigating Smell and Taste Disorders. Demos Medical Publishing. pp. 39–40. ISBN 978-1-932603-96-5. http://books.google.com/books?id=m6WOtX2QAtwC&pg=PA39. Retrieved 26 March 2011.
- ^ a b c Siegel, George J.; Albers, R. Wayne (2006). Basic neurochemistry: molecular, cellular, and medical aspects. Academic Press. p. 825. ISBN 978-0-12-088397-4. http://books.google.com/books?id=Af0IyHtGCMUC&pg=PA825. Retrieved 26 March 2011.
- ^
- Oh, Mama, What's Up With Umami? foxnews.com, January 05, 2010
- Umami Dearest: The mysterious fifth taste has dfficially infiltrated the food scene trendcentral.com, Feb 23rd, 2010
- #8 Food Trend for 2010: I Want My Umami foodchannel.com, Dec. 06, 2009
- ^ Food texture: measurement and perception (page 3–4/311) Andrew J. Rosenthal. Springer, 1999.
- ^ Why do two great tastes sometimes not taste great together? scientificamerican.com. Dr. Tim Jacob, Cardiff University. May 22, 2009.
- ^ E. R. Smith, D. M. Mackie (2000). Social Psychology. Psychology Press, 2nd ed., p. 20
References
- Goldstein, E. Bruce (13 February 2009). Sensation and perception. Cengage Learning. ISBN 978-0-495-60149-4. http://books.google.com/books?id=2tW91BWeNq4C. Retrieved 26 March 2011.
- Gregory, Richard L.; Zangwill, O. L. (1987). The Oxford companion to the mind. Oxford University Press. http://books.google.com/books?id=HRYoSwAACAAJ. Retrieved 24 March 2011.
Further reading
- Flanagan, J.R., Lederman, S.J. Neurobiology: Feeling bumps and holes, News and Views, Nature, 412(6845):389-91 (2001).
- James J. Gibson. The Senses Considered as Perceptual Systems. Boston 1966.
- James J. Gibson. The Ecological Approach to Visual Perception. Lawrence Erlbaum Associates, 1987. ISBN 0-89859-959-8
- Robles-De-La-Torre G. The Importance of the Sense of Touch in Virtual and Real Environments. IEEE Multimedia 13(3), Special issue on Haptic User Interfaces for Multimedia Systems, pp. 24–30 (2006).
External links
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- Theories of Perception Several different aspects on perception
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Translations:
Top
Perception
Dansk (Danish)
n. - sanseopfattelse
Nederlands (Dutch)
gewaarwording, besef, perceptie (filosofie), interpretatie/ opvatting
Français (French)
n. - (Philos, Psych) perception, idée, perspicacité, finesse, (Comm, Fisc) perception
Deutsch (German)
n. - Wahrnehmung, Empfindung, Wahrnehmungsvermögen, Vorstellung
Ελληνική (Greek)
n. - αντιληπτικότητα, αντίληψη (δια των αισθήσεων), αίσθηση
Italiano (Italian)
percezione, visione, intuizione
Português (Portuguese)
n. - percepção (f), idéia (f)
Русский (Russian)
осознание, понимание, восприятие
Español (Spanish)
n. - percepción, idea, noción, sensibilidad, comprensión
Svenska (Swedish)
n. - iakttagelseförmåga, varseblivning
中文（简体）(Chinese (Simplified))
知觉, 领悟力, 感觉
中文（繁體）(Chinese (Traditional))
n. - 知覺, 領悟力, 感覺
日本語 (Japanese)
n. - 知覚, 理解, 認識, 知覚されたもの
العربيه (Arabic)
(الاسم) إدراك حسي, إدراك للحقيقه
עברית (Hebrew)
n. - תפיסה, הבחנה, תחושה, השגה, קיבול
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