Scandinavian Journal of Psychology, 1992, 33, 282-287
On sensation, perception and thought: A reply to Ronnberg AXEL LARSEN Institute of Clinical Psychology, Copenhagen University, Copenhagen, Denmark
Larsen, A. (1991). On sensation, perception and thought: A reply to Rannberg. Scandinavian Journal of Psychology, 33, 282-287. A traditional partition of cognitive phenomena into sensation, perception and thought is reintroduced in response to reant arguments (Rennberg, 1990) for conditions that must be met in order to distinguish between perception and cognition. The suggested division seems grossly compatible with RBnnberg’s basic aim and receives support from several different l i e s of inquiry, including single cell recordings in the brain, neurospsychology, computational studies of vision and experimental psychology.
Key wordv: Sensation, perception, thought, cognition. Axel Lnrsen, Institute of Clinical Psychology, Copenhagen University, Njalsgade 90,DK-,2300 Copenhagen S., Denmark
In a recent short note in this journal, RBnnberg (1990) argued that perception and cognition should be theoretically distinguished when three criteria are met: (1) when perception and cognition serve different biological purposes, (2) when stimulus information is not sflicient for veridical perception, (3) when the task emphasizes explicit retrieval of information from memory as opposed to implicit use of information. When these criteria are not met, conditions for theoretical unification supposedly exist. Riinnberg’s remarks have prompted replies from Ggrling (1990), Runeson (1990), Hjelmquist (1990), and Montgomery (1991). Montgomery (1991) does not comment specifically on biological purpose, but Ggrling (1990), Runeson (1990), and Hjelmquist ( 1990) all oppose to the idea that biological purpose is useful in distinguishing between perception and cognition. I quite agree with the views offered by Garling (1990) and Hjelmquist (1990), namely that perception and cognition ultimately must serve a common biological purpose. In the present note a quite traditional division of human cognition into sensation, perception and thinking is reintroduced. I believe that this division receives support from many different lines of inquiry: (1) single cell recordings in the brain, (2) neuropsychology, (3) computational studies of vision, and (4) experimental psychology. In addition it also seems to fit in with R6nnberg’s (1990) basic endeavour and at the same time appears grossly compatible with Giirling’s (1990), Runeson’s (1990), Hjelmquist’s (1990), and Montgomery’s (1991) views. TERMINOLOGY AND AN EXAMPLE Consider a situation in which one observes two people shaking hands. One may describe what one sees in terms of local surface orientations and reflectances (colour), distance from viewer, discontinuities in depth etc., or in terms of full volumetric descriptions of differently coloured objects, some of which move and some of which are stationary (cf. also Marr, 1982). Alternatively the situation could be described in terms of Gibson’s (1950) world/field distinction (cf. also Bundesen, 1977). In either case, the scene is described by reference to
Scand J Rychol 33 (1992)
On sensation, perception and thought
visual appearance, that is visual impressions or visual sensations of a particular event are specified. Consider next the question of what those two people are doing. You may think that they are saying hello to each other, or that they are saying goodbye, or that they are closing a deal. Even though your sensations of the scene do not change, your perception does. Put simply perceiving means to know what is signalled by our senses. Perception presupposes sensation and knowledge (conceptual descriptions). A fixed set of sensory impressions may, as the handshaking example demonstrates, occasion many different conceptual interpretations. Conversely, a single conceptual interpretation (e.g. the letter “A” is present in the visual field) may pertain to many different visual impressions. It should be noticed that numerous studies of perception according to the suggested terminology in fact deal with sensation rather than perception. For example, Gunnar Johansson’s (1950) classic studies of motion, Ullman’s (1978) studies of motion correspondence, or our own studies of motion impletion (Larsen et d.,1983) all concern formation of visual sensations. SENSATION Sensations are caused by physical energy (photons, sound waves etc.) impinging on highly specialized receptor surfaces which output neural signals. Beginning with Kuffler’s ( 1953) and Hubel & Wiesel’s (1962, 1968) studies of neural signal processing in the visual pathways, single cell recordings have revealed an amazingly complex but well ordered visual architecture (Van Essen & Maunsell, 1983; Mishkin et al., 1983; Cowey, 1985; Desimone & Ungerleider, 1989). Of particular interest is the suggestion (see the review in Mishkin et al., 1983) that visual processing from primary visual cortex and onwards divides into a stream toward posterior parietal cortex, which probably relates to determining spatial location of objects (knowing where), and another stream toward inferior temporal cortex which relates to object recognition (knowing what). Lesions in the inferior temporal cortex in monkeys and in man produce deficits in visual object recognition in the apparent absence of any visual sensory losses or deficits on non-visual tasks (Gross, 1973). Observations of “not-knowing” (agnosia) in patients without degraded sensations, which date back to Sigmund Freud (1891), may extend to other sense modalities and may be auditory or tactile (Ellis & Young, 1988). Perception and sensation are usually intimately linked, but may be dissociated due to localized lesions in the brain. Attempts to model neural computations in the brain also support a distinction between sensation and perception. Computational investigations into visual signal processing suggest that signals from retinal photo receptors are filtered by Laplacian of Gaussian filters (Marr & Hildreth, 1980), which output zero-crossings corresponding to abrupt changes of intensity (edges, shadow contours) in the input. Zerocrossings in each visual field may in turn serve as input to modules that compute orientation and depth of visible surfaces, from which a full 3D visual representation may be assembled (Marr, 1982). As yet, this scheme has not been fully realized, but highly suggestive partial models do suggest that full 3D visual sensations can be computed bottom up without recourse to prior knowledge or hypotheses about what is actually represented in the images. However, as hinted at by Runeson (1990; for explicit discussions see Marr, 1982; Lowe, 1985) the vision problem or inverse projection problem cannot be solved unless visual systems are tuned (through natural selection or learning) to basic properties in the physical world.
283
284
A . Lursen
Scand J Psychol 33 (1992)
PERCEPTION Our sensory experience is under ordinary circumstances rich and highly vaned, but the number of objects (or perceptual units, see Woodworth, 1938) we can perceive (attend to or recognize) in any moment of time seems limited to about three or four for most people (Baddeley, 1981; 1983). For example, in Sperling’s (1960) classic experiment subjects were asked to report as many items as possible from a briefly exposed visual display of letters and digits. On the average, Sperling’s subjects reported slightly over four items; later studies (e.g. Shibuya & Bundesen, 1988) show slightly lower estimates. The liitation is not due to the limited sampling time (Colthart, 1972; Shibuya & Bundesen, 1988), but apparently reflects a genuine limitation on the number of objects we can think of at the same time. Our conceptual short-term store supposedly contains three or four slots, each pointing to one object or event, signalled by sensations (Bundesen et al., 1984; Bundesen, 1990). A slot or object file (Treisman et af., 1983) may very likely hold many concepts, allowing for multiple categorizations of an object. Except for rare instances with ambiguous or degraded stimuli like Necker Cube demonstrations, stereoscopic viewing of random dot stereograms or apparent motion, there is generally tittle top-down control of the formation of sensory impressions. In contrast, even though sensation specifies units or events for perception, a subject may exercise considerable control on what he perceives. For example, Cherry’s (1953) and Broadbent’s ( 1958) classic studies of dichotic listening demonstrate that subjects may attend to or perceive information on one channel to the exclusion of perceptual pick-up of information on other channels (filtering). Filtering is not always perfect, however. A subject will often perceive his own name, when it is presented on the unattended ear in a sequence of words (Moray, 1959). Filtering seems even less perfect in vision in which irrelevant distractors will often intrude. In a Sperling type of task, Bundesen et al. (1984, Experiment 11) asked subjects to report white (or black) letters from a display of white and black letters. Under simplifying assumptions, if subjects cannot filter their visual impression of stimulus items, the probability that the first reported item is a target should be equal to T / ( D T),and the probability that the first reported item is a distractor should equal D / ( D + T), where T and D are number of targets and number of distractors, respectively. Thus, given nonselectivity, targets and distractors are simply assumed to have equal weight (Bundesen et al., 1984). Subjects were able to filter black (white) letters fairly efficiently; the weight of distractor letters were estimated to 2-5% of the weight of target letters. When asked to select targets defined on the basis of alphanumeric class (e.g. letters among letters and digits) selection was much less efficient, with distractor weights about 50% of target weights. Thus, attentional control of perception may be based on simple “physical” properties (like colour) or on the meaning (category) of sensations (cf. also Duncan, 1983). In a new theory of visual attention and selection, Bundesen (1990) has shown how a few simple mechanisms can account for these and other findings in visual recognition, selection and search.
+
THOUGHT
__
Perception is often effortless and immediate, for instance when you recognize an animal, the smell of basil or the letter A . But it need not be, say when it gradually dawns on you after numerous attempts to find a good move that your position in a game of chess is hopeless. Thus, perception may be mediated by inference and hypothesis testing, and it may gradually approach thinking by becoming less and less directly based on sensation and more and more on inference, knowledge and concepts (Bruner ef uf.,1956).
Scand J Psycho1 33 (1992)
On sensntion, perception and thought
Our ability to manipulate symbols (concepts) that designate other symbols or objects is basic to abstract thought and is a key assumption in influential attempts to model thought processes (Newell & Simon, 1972; Anderson, 1983). However, imagined objects, that are neither actually present and sensed nor abstract like concepts, also play important roles in thinking. For example, when people solve problems they often report using visual-spatial models to imagine how a scene would look if one or several objects were moved around or hooked together. A solution may be found by reading o f f (classifying) the imaginally transformed scene (cf. Shepard, 1978; Shepard & Cooper, 1982). Visual and other types of imagery should thus simulate actions and sensations generated by actions in the real world. Mental imagery bears resemblance to sensation. There is fairly strong evidence of resemblance between sensation of apparent rotational movement (Shepard & Judd, 1976) and mental rotation of visual images (Shepard & Metzler, 1971). There is also support for the resemblance of mental transformation of size (Bundesen & Larsen, 1975), which may be resolved as mental translation in depth (Bundesen et al., 1981), and apparent visual motion in depth (Bundesen et al., 1983). Moreover, combinations of transformations of size and orientation in visual imagery (Bundesen et al., 1981; Larsen, 1985) are parallelled by corresponding sensations of screwlike helical motion back and forth in depth in response to alternating stimuli that are the same in shape, but different in size and orientation (Bundesen et al., 1983). For each of these image transformations, the temporal pattern of RT's in the image domain is matched by a similar pattern of the minimum required SOA's (stimulus onset asynchronies) for registering the corresponding apparent motion in the domain of sensation. CONCLUSION 1 To know what is transmitted by our senses, i.e. to perceive, entails that we use concepts to interpret our sensations. Perception thus links two fundamentally different modes of cognition: objects or events signalled by sensory systems (sensation) and active conceptual descriptions (thought). Many of the ideas reported in this paper were developed during discussions with Claw Bundesen. His contribution is gratefully acknowledged.
REFERENCES Anderson, J. R. ( 1983). The architecture of cognition. Cambridge, Ma.: Harvard University Press. Baddeley, A. D. (1981). The concept of working memory. A view of its current state and probable future development. Cognition, 10, 17-23. Baddeley, A. D. (1983). Working memory. Philosophical Transactions of the Royal Society of London, Series E, 302, 3 1 1 -324. Broadbent, D. A. (1958). Perception and communication. London: Pergamon Press. Bruner, J. S., Goodnow, J. J. & Austin, G. A. (1956). A study of thinking. New York Wiley. Bundesen, C. (1977). Concept of visual sensation. Perceptual and Motor Skills, 44, 1191-1205. Bundesen, C. (1990). A theory of visual attention. Psychological Review, 97, 523-547. Bundesen, C. & Larsen, A. (1975). Visual transformation of size. Journal oJ Experimental Psychology: Human Perception and Performance, I , 214-220. Bundesen, C., Larsen, A. & Farrell, J. E. (1981). Mental transformations of size and orientation. In M. I. Posner & 0. S. M. Marin (Eds.), Attention andperformance XI, (pp. 631-649). Hillsdale, N. J.: Erlbaum. Bundesen, C., Larsen, A. & Farrell, J. E. (1983). Visual apparent movement: Transformations of sue and orientation. Perception, 12. 549-558. Bundesen, C., Pedersen, L. F. & Larsen, A. (1984). Measuring efficiency of selection from briefly exposed visual displays: A model for partial report. Journal of Experimental Psychology: Human Perception and Performance, lo, 329-339.
285
286
A . Larsen
Scand J Psycho1 33 (1992)
Cherry, E.C. (1953). Some experiments on the recognition of speech, with one and with two ears. Journal of the Acorcstical Society of America, 25, 975-979. Coltheart, M. (1972). Visual infomation processing. In P. C.Dodwell (Ed.), New horizons in psychology (Vol. 2, pp. 62-85). Harmondsworth, England Penguin Books. Cowey, A. (1985). Aspects of cortical organization related to selective attention and selective impairments of visual perception: A tutorial review. In M. I. Posner & 0. S. M. Marin (Eds), Attention and performance XI (pp. 41-68) Hillsdale, N. J.: Erlbaum. Gross, C. G. (1973). Visual functions of inferotempral cortex. In R. Jung (Ed.), Handbook of sensory psychology vol. VII/3,Centralprocessing of sensory information, Part B (pp. 451 -482). Berlin: Springer Verlag. Desimone, R & Ungerleider, L. G. (1989). Neural mechanisms of visual processing in monkeys. In R. Boller & F.Grafman (Eds), H d o o k of neurupsychology, (Vol.2, pp. 267-299). New York Elsevier. .Duncan, J. (1983). Perceptual selection based on alphanumeric class: Evidence from partical reports. Perception (I Psychophysics, 33, 533-547. Elliis, A. W. & Young, A. W. (1988). Human cognitive neuropsychology. Hove & London: Lawrence Erlbaum. Freud, S. (1891). Zur Auffassing der Aphasien. LeipzigIWien: F. Deuticke. Gibson, J. J. ( 1950). The perception of the uirunl world. Boston: Houghton Mifflin. Grling, T. (1990). A commentary on Ronnberg’s distinction between perception and cognition. Scandinavian Journal of Psychology, 31. 220-222. Hjelmquist, E. (1990). Differentiation and unification in perception and cognition. Scandinavian Journal o/Psychology, 31, 315-317. Hubel, D. H. & Wiesel, T. N. (1962). Receptive fields, binocular interaction and functional architecture in the cat’s visual cortex. Journal of Physiology, 166, 106-154. Hubel, D. H. & Wiesel, T. N. ( 1968). Receptive fields and functional architectureof monkey striate cortex. Journal of Physiology, 196, 215-243. Johansson, G. (1950). Confgurations in event perception. Uppsala: Almquist & Wiksell. Kuffler, S. W. (1953). Discharge patterns and functional organization of mammalian retina. Journal of N~OphySiolOgy,16, 37-68. Larsen, A. (1985). Pattern matching: Effects of size ratio, angular difference in orientation, and familiarity. Perception & Psychophysics, 38, 63-68. Larsen, A., Famll, J. E. & Bundesen, C. (1983). Short- and long-range processes in visual apparent movement. Psychological Research, 45, 1 1- 18. Lowe, D. G. ( 1985). Perceptual organization and visual recognition. Boston: Kluwer. Man, D. (1982). Vision. San Francisco: Freeman. Marr, D. & Hildreth, E. (1980). Theory of edge detection. Proceedings of rhe Royal Society of London, Series B, 207, 187-217. Mishkin, M.,Ungerleider, L. G. & Macko, K. A. (1983). Object vision and spatial vision: Two cortical pathways. Trends in Neuroscience, 6, 414-417. Montgomery, H. (1991). Perception: The interface between cognition and the external world. Scandinavian Journal Of PSyChOlOgy, 32, 82-85. Moray, N. (1959). Attention in dichotic listening: Atfective cues and the inRuence of instructions. Quarterly Journal of Experimental Psychology, 11, 56-60. Newell, A. & Simon, H. A. (1972). Human problem solving. London: Prentia Hall. Runeson, S. (1990). Mode distinctions in knowing: The view from perception. Comments on Ronnberg (1990). Scandinavian Journal of Psychology, 31, 223-227. Rhnberg, J. (1990). On the distinction between perception and cognition. Scandinavian Journal of PySChOlogy, 31, 154-156. Shepard. R. N. (1978). Externaliuation of mental images and the act of creation. In B. S. Randhawa & W. E. Coffman. (Eds), Visual learning, rhinking. and communication (pp. 139-189). New York Academic Press. Shepard, R. N. & Cooper, L. A. (1982). Mental inrages and their tramformatwns. Cambridge, M A MIT Press/Bradford Books. Shepard, R. N. & Judd, S. A. (1976). Perceptual illusion of rotation of three-dimensional objects. Science, 191, 952-954.
Shepard, R. N. & Merzler, J. (1971). Mental rotation of three-dimensional objects. Science, 191,952-954. Shibuya, H. & Bundesen, C (1988). Visual selection from multielement displays: Measuring and modeling effects of exposure duration. J o u m l of Experimental Psychology: H m Perception and Performce, 14, 591-600.
S a n d J Psycho1 33 (1992)
On sensation, perception and thought
Sperling, G. ( 1960). The information available in brief visual presentations. Psychological Monographs, 74, ( 1 l), 1-29. Treisman, A., Kahneman, D. & Burkell, J. (1983). Perceptual objects and the cost of filtering. Perception & PSyChOphysicS, 33, 527-532. Ullman, S. ( 1979). The interpretation of visual motion. Cambridge, Mass.: MIT Press. Van Essen, D. C. & Maunsell, J. H. R. (1983). Hierarchical organization and functional streams in visual cortex. Trenh in Neuroscience, 6, 370-375. Woodworth, R. S. (1938). Experimental Psychology. New York Holt. Received 3 July 1991
287
On sensation, perception and thought: A reply to Ronnberg AXEL LARSEN Institute of Clinical Psychology, Copenhagen University, Copenhagen, Denmark
Larsen, A. (1991). On sensation, perception and thought: A reply to Rannberg. Scandinavian Journal of Psychology, 33, 282-287. A traditional partition of cognitive phenomena into sensation, perception and thought is reintroduced in response to reant arguments (Rennberg, 1990) for conditions that must be met in order to distinguish between perception and cognition. The suggested division seems grossly compatible with RBnnberg’s basic aim and receives support from several different l i e s of inquiry, including single cell recordings in the brain, neurospsychology, computational studies of vision and experimental psychology.
Key wordv: Sensation, perception, thought, cognition. Axel Lnrsen, Institute of Clinical Psychology, Copenhagen University, Njalsgade 90,DK-,2300 Copenhagen S., Denmark
In a recent short note in this journal, RBnnberg (1990) argued that perception and cognition should be theoretically distinguished when three criteria are met: (1) when perception and cognition serve different biological purposes, (2) when stimulus information is not sflicient for veridical perception, (3) when the task emphasizes explicit retrieval of information from memory as opposed to implicit use of information. When these criteria are not met, conditions for theoretical unification supposedly exist. Riinnberg’s remarks have prompted replies from Ggrling (1990), Runeson (1990), Hjelmquist (1990), and Montgomery (1991). Montgomery (1991) does not comment specifically on biological purpose, but Ggrling (1990), Runeson (1990), and Hjelmquist ( 1990) all oppose to the idea that biological purpose is useful in distinguishing between perception and cognition. I quite agree with the views offered by Garling (1990) and Hjelmquist (1990), namely that perception and cognition ultimately must serve a common biological purpose. In the present note a quite traditional division of human cognition into sensation, perception and thinking is reintroduced. I believe that this division receives support from many different lines of inquiry: (1) single cell recordings in the brain, (2) neuropsychology, (3) computational studies of vision, and (4) experimental psychology. In addition it also seems to fit in with R6nnberg’s (1990) basic endeavour and at the same time appears grossly compatible with Giirling’s (1990), Runeson’s (1990), Hjelmquist’s (1990), and Montgomery’s (1991) views. TERMINOLOGY AND AN EXAMPLE Consider a situation in which one observes two people shaking hands. One may describe what one sees in terms of local surface orientations and reflectances (colour), distance from viewer, discontinuities in depth etc., or in terms of full volumetric descriptions of differently coloured objects, some of which move and some of which are stationary (cf. also Marr, 1982). Alternatively the situation could be described in terms of Gibson’s (1950) world/field distinction (cf. also Bundesen, 1977). In either case, the scene is described by reference to
Scand J Rychol 33 (1992)
On sensation, perception and thought
visual appearance, that is visual impressions or visual sensations of a particular event are specified. Consider next the question of what those two people are doing. You may think that they are saying hello to each other, or that they are saying goodbye, or that they are closing a deal. Even though your sensations of the scene do not change, your perception does. Put simply perceiving means to know what is signalled by our senses. Perception presupposes sensation and knowledge (conceptual descriptions). A fixed set of sensory impressions may, as the handshaking example demonstrates, occasion many different conceptual interpretations. Conversely, a single conceptual interpretation (e.g. the letter “A” is present in the visual field) may pertain to many different visual impressions. It should be noticed that numerous studies of perception according to the suggested terminology in fact deal with sensation rather than perception. For example, Gunnar Johansson’s (1950) classic studies of motion, Ullman’s (1978) studies of motion correspondence, or our own studies of motion impletion (Larsen et d.,1983) all concern formation of visual sensations. SENSATION Sensations are caused by physical energy (photons, sound waves etc.) impinging on highly specialized receptor surfaces which output neural signals. Beginning with Kuffler’s ( 1953) and Hubel & Wiesel’s (1962, 1968) studies of neural signal processing in the visual pathways, single cell recordings have revealed an amazingly complex but well ordered visual architecture (Van Essen & Maunsell, 1983; Mishkin et al., 1983; Cowey, 1985; Desimone & Ungerleider, 1989). Of particular interest is the suggestion (see the review in Mishkin et al., 1983) that visual processing from primary visual cortex and onwards divides into a stream toward posterior parietal cortex, which probably relates to determining spatial location of objects (knowing where), and another stream toward inferior temporal cortex which relates to object recognition (knowing what). Lesions in the inferior temporal cortex in monkeys and in man produce deficits in visual object recognition in the apparent absence of any visual sensory losses or deficits on non-visual tasks (Gross, 1973). Observations of “not-knowing” (agnosia) in patients without degraded sensations, which date back to Sigmund Freud (1891), may extend to other sense modalities and may be auditory or tactile (Ellis & Young, 1988). Perception and sensation are usually intimately linked, but may be dissociated due to localized lesions in the brain. Attempts to model neural computations in the brain also support a distinction between sensation and perception. Computational investigations into visual signal processing suggest that signals from retinal photo receptors are filtered by Laplacian of Gaussian filters (Marr & Hildreth, 1980), which output zero-crossings corresponding to abrupt changes of intensity (edges, shadow contours) in the input. Zerocrossings in each visual field may in turn serve as input to modules that compute orientation and depth of visible surfaces, from which a full 3D visual representation may be assembled (Marr, 1982). As yet, this scheme has not been fully realized, but highly suggestive partial models do suggest that full 3D visual sensations can be computed bottom up without recourse to prior knowledge or hypotheses about what is actually represented in the images. However, as hinted at by Runeson (1990; for explicit discussions see Marr, 1982; Lowe, 1985) the vision problem or inverse projection problem cannot be solved unless visual systems are tuned (through natural selection or learning) to basic properties in the physical world.
283
284
A . Lursen
Scand J Psychol 33 (1992)
PERCEPTION Our sensory experience is under ordinary circumstances rich and highly vaned, but the number of objects (or perceptual units, see Woodworth, 1938) we can perceive (attend to or recognize) in any moment of time seems limited to about three or four for most people (Baddeley, 1981; 1983). For example, in Sperling’s (1960) classic experiment subjects were asked to report as many items as possible from a briefly exposed visual display of letters and digits. On the average, Sperling’s subjects reported slightly over four items; later studies (e.g. Shibuya & Bundesen, 1988) show slightly lower estimates. The liitation is not due to the limited sampling time (Colthart, 1972; Shibuya & Bundesen, 1988), but apparently reflects a genuine limitation on the number of objects we can think of at the same time. Our conceptual short-term store supposedly contains three or four slots, each pointing to one object or event, signalled by sensations (Bundesen et al., 1984; Bundesen, 1990). A slot or object file (Treisman et af., 1983) may very likely hold many concepts, allowing for multiple categorizations of an object. Except for rare instances with ambiguous or degraded stimuli like Necker Cube demonstrations, stereoscopic viewing of random dot stereograms or apparent motion, there is generally tittle top-down control of the formation of sensory impressions. In contrast, even though sensation specifies units or events for perception, a subject may exercise considerable control on what he perceives. For example, Cherry’s (1953) and Broadbent’s ( 1958) classic studies of dichotic listening demonstrate that subjects may attend to or perceive information on one channel to the exclusion of perceptual pick-up of information on other channels (filtering). Filtering is not always perfect, however. A subject will often perceive his own name, when it is presented on the unattended ear in a sequence of words (Moray, 1959). Filtering seems even less perfect in vision in which irrelevant distractors will often intrude. In a Sperling type of task, Bundesen et al. (1984, Experiment 11) asked subjects to report white (or black) letters from a display of white and black letters. Under simplifying assumptions, if subjects cannot filter their visual impression of stimulus items, the probability that the first reported item is a target should be equal to T / ( D T),and the probability that the first reported item is a distractor should equal D / ( D + T), where T and D are number of targets and number of distractors, respectively. Thus, given nonselectivity, targets and distractors are simply assumed to have equal weight (Bundesen et al., 1984). Subjects were able to filter black (white) letters fairly efficiently; the weight of distractor letters were estimated to 2-5% of the weight of target letters. When asked to select targets defined on the basis of alphanumeric class (e.g. letters among letters and digits) selection was much less efficient, with distractor weights about 50% of target weights. Thus, attentional control of perception may be based on simple “physical” properties (like colour) or on the meaning (category) of sensations (cf. also Duncan, 1983). In a new theory of visual attention and selection, Bundesen (1990) has shown how a few simple mechanisms can account for these and other findings in visual recognition, selection and search.
+
THOUGHT
__
Perception is often effortless and immediate, for instance when you recognize an animal, the smell of basil or the letter A . But it need not be, say when it gradually dawns on you after numerous attempts to find a good move that your position in a game of chess is hopeless. Thus, perception may be mediated by inference and hypothesis testing, and it may gradually approach thinking by becoming less and less directly based on sensation and more and more on inference, knowledge and concepts (Bruner ef uf.,1956).
Scand J Psycho1 33 (1992)
On sensntion, perception and thought
Our ability to manipulate symbols (concepts) that designate other symbols or objects is basic to abstract thought and is a key assumption in influential attempts to model thought processes (Newell & Simon, 1972; Anderson, 1983). However, imagined objects, that are neither actually present and sensed nor abstract like concepts, also play important roles in thinking. For example, when people solve problems they often report using visual-spatial models to imagine how a scene would look if one or several objects were moved around or hooked together. A solution may be found by reading o f f (classifying) the imaginally transformed scene (cf. Shepard, 1978; Shepard & Cooper, 1982). Visual and other types of imagery should thus simulate actions and sensations generated by actions in the real world. Mental imagery bears resemblance to sensation. There is fairly strong evidence of resemblance between sensation of apparent rotational movement (Shepard & Judd, 1976) and mental rotation of visual images (Shepard & Metzler, 1971). There is also support for the resemblance of mental transformation of size (Bundesen & Larsen, 1975), which may be resolved as mental translation in depth (Bundesen et al., 1981), and apparent visual motion in depth (Bundesen et al., 1983). Moreover, combinations of transformations of size and orientation in visual imagery (Bundesen et al., 1981; Larsen, 1985) are parallelled by corresponding sensations of screwlike helical motion back and forth in depth in response to alternating stimuli that are the same in shape, but different in size and orientation (Bundesen et al., 1983). For each of these image transformations, the temporal pattern of RT's in the image domain is matched by a similar pattern of the minimum required SOA's (stimulus onset asynchronies) for registering the corresponding apparent motion in the domain of sensation. CONCLUSION 1 To know what is transmitted by our senses, i.e. to perceive, entails that we use concepts to interpret our sensations. Perception thus links two fundamentally different modes of cognition: objects or events signalled by sensory systems (sensation) and active conceptual descriptions (thought). Many of the ideas reported in this paper were developed during discussions with Claw Bundesen. His contribution is gratefully acknowledged.
REFERENCES Anderson, J. R. ( 1983). The architecture of cognition. Cambridge, Ma.: Harvard University Press. Baddeley, A. D. (1981). The concept of working memory. A view of its current state and probable future development. Cognition, 10, 17-23. Baddeley, A. D. (1983). Working memory. Philosophical Transactions of the Royal Society of London, Series E, 302, 3 1 1 -324. Broadbent, D. A. (1958). Perception and communication. London: Pergamon Press. Bruner, J. S., Goodnow, J. J. & Austin, G. A. (1956). A study of thinking. New York Wiley. Bundesen, C. (1977). Concept of visual sensation. Perceptual and Motor Skills, 44, 1191-1205. Bundesen, C. (1990). A theory of visual attention. Psychological Review, 97, 523-547. Bundesen, C. & Larsen, A. (1975). Visual transformation of size. Journal oJ Experimental Psychology: Human Perception and Performance, I , 214-220. Bundesen, C., Larsen, A. & Farrell, J. E. (1981). Mental transformations of size and orientation. In M. I. Posner & 0. S. M. Marin (Eds.), Attention andperformance XI, (pp. 631-649). Hillsdale, N. J.: Erlbaum. Bundesen, C., Larsen, A. & Farrell, J. E. (1983). Visual apparent movement: Transformations of sue and orientation. Perception, 12. 549-558. Bundesen, C., Pedersen, L. F. & Larsen, A. (1984). Measuring efficiency of selection from briefly exposed visual displays: A model for partial report. Journal of Experimental Psychology: Human Perception and Performance, lo, 329-339.
285
286
A . Larsen
Scand J Psycho1 33 (1992)
Cherry, E.C. (1953). Some experiments on the recognition of speech, with one and with two ears. Journal of the Acorcstical Society of America, 25, 975-979. Coltheart, M. (1972). Visual infomation processing. In P. C.Dodwell (Ed.), New horizons in psychology (Vol. 2, pp. 62-85). Harmondsworth, England Penguin Books. Cowey, A. (1985). Aspects of cortical organization related to selective attention and selective impairments of visual perception: A tutorial review. In M. I. Posner & 0. S. M. Marin (Eds), Attention and performance XI (pp. 41-68) Hillsdale, N. J.: Erlbaum. Gross, C. G. (1973). Visual functions of inferotempral cortex. In R. Jung (Ed.), Handbook of sensory psychology vol. VII/3,Centralprocessing of sensory information, Part B (pp. 451 -482). Berlin: Springer Verlag. Desimone, R & Ungerleider, L. G. (1989). Neural mechanisms of visual processing in monkeys. In R. Boller & F.Grafman (Eds), H d o o k of neurupsychology, (Vol.2, pp. 267-299). New York Elsevier. .Duncan, J. (1983). Perceptual selection based on alphanumeric class: Evidence from partical reports. Perception (I Psychophysics, 33, 533-547. Elliis, A. W. & Young, A. W. (1988). Human cognitive neuropsychology. Hove & London: Lawrence Erlbaum. Freud, S. (1891). Zur Auffassing der Aphasien. LeipzigIWien: F. Deuticke. Gibson, J. J. ( 1950). The perception of the uirunl world. Boston: Houghton Mifflin. Grling, T. (1990). A commentary on Ronnberg’s distinction between perception and cognition. Scandinavian Journal of Psychology, 31. 220-222. Hjelmquist, E. (1990). Differentiation and unification in perception and cognition. Scandinavian Journal o/Psychology, 31, 315-317. Hubel, D. H. & Wiesel, T. N. (1962). Receptive fields, binocular interaction and functional architecture in the cat’s visual cortex. Journal of Physiology, 166, 106-154. Hubel, D. H. & Wiesel, T. N. ( 1968). Receptive fields and functional architectureof monkey striate cortex. Journal of Physiology, 196, 215-243. Johansson, G. (1950). Confgurations in event perception. Uppsala: Almquist & Wiksell. Kuffler, S. W. (1953). Discharge patterns and functional organization of mammalian retina. Journal of N~OphySiolOgy,16, 37-68. Larsen, A. (1985). Pattern matching: Effects of size ratio, angular difference in orientation, and familiarity. Perception & Psychophysics, 38, 63-68. Larsen, A., Famll, J. E. & Bundesen, C. (1983). Short- and long-range processes in visual apparent movement. Psychological Research, 45, 1 1- 18. Lowe, D. G. ( 1985). Perceptual organization and visual recognition. Boston: Kluwer. Man, D. (1982). Vision. San Francisco: Freeman. Marr, D. & Hildreth, E. (1980). Theory of edge detection. Proceedings of rhe Royal Society of London, Series B, 207, 187-217. Mishkin, M.,Ungerleider, L. G. & Macko, K. A. (1983). Object vision and spatial vision: Two cortical pathways. Trends in Neuroscience, 6, 414-417. Montgomery, H. (1991). Perception: The interface between cognition and the external world. Scandinavian Journal Of PSyChOlOgy, 32, 82-85. Moray, N. (1959). Attention in dichotic listening: Atfective cues and the inRuence of instructions. Quarterly Journal of Experimental Psychology, 11, 56-60. Newell, A. & Simon, H. A. (1972). Human problem solving. London: Prentia Hall. Runeson, S. (1990). Mode distinctions in knowing: The view from perception. Comments on Ronnberg (1990). Scandinavian Journal of Psychology, 31, 223-227. Rhnberg, J. (1990). On the distinction between perception and cognition. Scandinavian Journal of PySChOlogy, 31, 154-156. Shepard. R. N. (1978). Externaliuation of mental images and the act of creation. In B. S. Randhawa & W. E. Coffman. (Eds), Visual learning, rhinking. and communication (pp. 139-189). New York Academic Press. Shepard, R. N. & Cooper, L. A. (1982). Mental inrages and their tramformatwns. Cambridge, M A MIT Press/Bradford Books. Shepard, R. N. & Judd, S. A. (1976). Perceptual illusion of rotation of three-dimensional objects. Science, 191, 952-954.
Shepard, R. N. & Merzler, J. (1971). Mental rotation of three-dimensional objects. Science, 191,952-954. Shibuya, H. & Bundesen, C (1988). Visual selection from multielement displays: Measuring and modeling effects of exposure duration. J o u m l of Experimental Psychology: H m Perception and Performce, 14, 591-600.
S a n d J Psycho1 33 (1992)
On sensation, perception and thought
Sperling, G. ( 1960). The information available in brief visual presentations. Psychological Monographs, 74, ( 1 l), 1-29. Treisman, A., Kahneman, D. & Burkell, J. (1983). Perceptual objects and the cost of filtering. Perception & PSyChOphysicS, 33, 527-532. Ullman, S. ( 1979). The interpretation of visual motion. Cambridge, Mass.: MIT Press. Van Essen, D. C. & Maunsell, J. H. R. (1983). Hierarchical organization and functional streams in visual cortex. Trenh in Neuroscience, 6, 370-375. Woodworth, R. S. (1938). Experimental Psychology. New York Holt. Received 3 July 1991
287
