- Email: [email protected]
Mindblindness. An Essay on Autism and Theory of Mind
B OO K constituted by four thorough essays on the theme of human intelligence, but it is left to the reader to compose a fifth essay on the definition of intelligence in humans! Moreover, it is not clear what the target audience is meant to be. Given the extremely broad coverage of many disciplines, the volume is not suitable as a course textbook. Nevertheless, the book offers several valuable short and readable syntheses of the current knowledge of specific topics. For example, the chapters by R.L. Holloway, P.V. Tobias and P. Rakic examine the timing and mode of cortical
specification in the human brain from two completely different viewpoints, and constitute short and excellent syntheses of their own works on this topic. This book has a refreshing excitement to it, and infinite other possible approaches to this study have yet to be elucidated. I would therefore strongly recommend it to readers working in one of the fields covered here.
1 Falk, D. (1990) Behav. Brain Sci. 13, 333–381 2 Clutton-Brock, T.H. and Harvey, P.H. (1980) J. Zool. 190, 309–323 3 Martin, R.W. (1983) Fifty-second James Arthur Lecture on the Evolution of the Human Brain, Am. Museum Nat. History 4 Tishkoff, S.A. et al. (1996) Science 271, 1380 –1387 5 Allman, J. (1990) in Cerebral Cortex (Vol. 8A) ( Jones, E.G. and Peters, A., eds), pp. 269–283, Plenum Publishing Corporation 6 Pinker, S. and Bloom, P. (1990) Behav. Brain Sci. 13, 707–784 7 Schull, J. (1990) Behav. Brain Sci. 13, 63–108
Emmanuel Gilissen Division of Biology, Caltech 216-76, Pasadena, CA 91125, USA.
Mindblindness. An Essay on Autism and Theory of Mind by Simon Baron-Cohen, MIT Press, 1995. £17.95 (xxii + 171 pages) ISBN 0 262 02384 9 Blind to mind? It rhymes, and perhaps exactly such a poetic query might occur to those unfamiliar with the field of ‘theory of mind’ who find themselves thumbing through Baron-Cohen’s Mindblindness. After all, it is an especially intriguing book in which developmental pathologies, evolutionary scenarios, studies of the social intelligence of chimpanzees and children, and lines from Shakespeare, Emerson, Shelley and Byron, are all woven together into an account of the development and evolution of humanity’s most puzzling cognitive achievement – our ability to make inferences about the unobservable mental lives of ourselves and those around us. Baron-Cohen presents a model in which four purported brain modules interact to produce the human ‘mindreading’ system – our ability to represent and reason about the inner mental states of ourselves and others. The intellectual motivation for characterizing the mindreading system in terms of modules derives from Jerry Fodor’s1 resurrection of separate brain mechanisms, each relatively independent of the other, serving specific functions. In the spirit of Alan Leslie and David Premack, Baron-Cohen offers his own list of four prepackaged theory-of-mind brain modules, each performing specialized computations which ultimately interact to produce the human mindreading system: an Intentionality Detector (ID), an Eye Direction Detector (EDD), a Shared Attention Mechanism (SAM), and a Theory of Mind Mechanism (ToMM). First, ID is envisioned as a hardwired perceptual device which interprets moving stimuli in terms of desires and goals. In parallel, EDD is envisioned as detecting the presence and direction of eyes, and also interprets gaze as ‘seeing’ (does she see that?). Both ID and EDD produce inputs into SAM, which is envisioned as forming relationships among the self,
References
other agents and objects (do you and I see the same thing?). Finally, ToMM is seen as unifying the separate notions of attention, desire, intention, and knowledge and belief, into a coherent theoretical apparatus for understanding behavior in mentalistic terms – a theory of mind. If everyday humans are mindreaders, then who are the ‘mindblind’ to which the title of Baron-Cohen’s essay refers? Baron-Cohen proposes that the syndrome of autism might be characterized in exactly this manner: mindblindness. In the early 1980s, Baron-Cohen was among the first to propose that the cognitive development of autistic persons might be very different from that of normal children; in short, they might possess a profound dysfunction in theory of mind2. Autistic persons might, to a large extent, be unaware of the existence of many of the mental states that we take for granted. Much of Baron-Cohen’s book is devoted to reviewing his and others’ innovative work investigating theory-ofmind limitations in autistic persons, and in speculating on how different subgroups of autism might be the result of slightly different impairments in various modules of his hypothesized mindreading system. Baron-Cohen’s book is fascinating and far-reaching, but we wish to focus on a recurring theme of his essay concerning the evolution of theory of mind. On the surface, his account of the evolution of the mindreading system seems plausible. Evolution has designed the component brain modules that social creatures need to navigate their way through the complex social milieu of group-living. For example, throughout Chapter 3, Baron-Cohen turns to the Machiavellian Intelligence hypothesis (originally espoused by Alison Jolly in the mid-1960s) as an appropriate way of thinking about the evolution of the mindreading system. Here, it is the social complexity of group-living that has created a
Copyright © 1996, Elsevier Science Ltd. All rights reserved. 0166 - 2236/96/$15.00
selective context for favoring animals that possessed intellectual structures capable of coping with the daily ins and outs of being part of a social community, and ultimately, according to Baron-Cohen, the mindreading system. Just imagine what an advantage it would be, Baron-Cohen prods us, if you could anticipate what your rivals were likely to do next. And what better way of anticipating their next move, than to assess their inner mental states? Who is she paying attention to? What does he want? What does she know? To BaronCohen the implications are obvious: ‘The lack of competitive alternatives to mindreading that could produce equal or better success…makes it clearer why natural selection might have latched onto mindreading as an adaptive solution to the problem of predicting behavior and sharing information’ (p. 30). Without debating the potential utility of theory of mind in a social context, let us sketch a very different picture of the evolution of this cognitive system that is emerging from our research comparing theory-of-mind development in young children and its expression (or lack thereof) in chimpanzees. Take the case of gaze-following, which Baron-Cohen uses as evidence of the presence of EDD in human infants. He notes that by nine months or so children begin following the line-of-sight of others. By 18 months this behavior is well consolidated. Just look behind a 2-year-old and watch them spin around as if to check to see what you are looking at. But, as he notes, our research shows that this sight gag works equally well with chimpanzees3–5. On the one hand, we might have no problem with this. Chimpanzees are highly social creatures who are Machiavellian beasts par excellance: they gaze into each others’ eyes as if to extract meaning, and ‘manipulate’ and ‘deceive’ their way through highly competitive social situations6. Therefore, in the context of their gaze-following abilities, why not just grant them an understanding of the intentionality of ‘seeing’? The problem is that comparative work with chimpanzees and
PII: S0166-2236(96)60013-7
TINS Vol. 19, No. 7, 1996
299
R E V I E WS
B OO K
R EV I EWS young children reveals that, whereas human toddlers and preschoolers seem to develop a system for interpreting each others’ (and their own) behavior in mentalistic ways, chimpanzees might be doing neither3–5,7. Thus, although chimpanzees are masters at using each others’ gaze to discover things not in their immediate visual field, every method we have developed to ask them, do you understand that vision is about (or refers to) something?, they have unselfconsciously replied, ‘no’3. This discovery of an apparent dissociation between sophisticated gazefollowing and an appreciation of the mental state of attention behind gaze, raises troubling questions. On the one hand, it raises the question of whether the behaviors Baron-Cohen cites as evidence of shared attention in 9- to 18-month-olds (that is, pointing, gaze-following, gaze-alternation), are really an indication of an understanding of the mental state of attention. If apes follow your gaze without appreciating the attentional states behind it, so too might human infants. However, it is possible that we need to be prepared to think differently about certain behaviors depending on whether apes or human infants are displaying them. Perhaps when apes engage in ‘shared attention’ behaviors they do not understand them in a mentalistic fashion, but when human infants engage in the exact same behaviors they do. Before we are attacked for creating a double-standard, consider the following. Might it not be the case that gaze-following, deception, and the like are fairly ancient behavioral mechanisms which evolved long before anything like SAM or ToMM were in place? Perhaps it is our species alone that has specialized in representing each other’s mental states, and in doing so have been placed in the unique position of being able to reinterpret ancestral behavioral patterns, which evolved long before humans appeared on the scene3. For example, after following someone’s gaze, when is it, exactly, that humans wonder what it is they are looking at? Does our behavior follow from the mentalistic query, or is it exactly the reverse? We suspect that much of the social value of theory of mind occurs in
exactly this retrospective way – as a means for planning future social action, not as a means of solving on-line social problems. To put the point directly, whereas BaronCohen (and others) tend to describe social creatures as needing a powerful theory of mind in the thick of social situations (pp. 23–30), we envision nearly the opposite: what they need most is a means of quickly selecting the appropriate behavioral script in order to act rapidly. Theory of mind is an added bonus. Thus, in humans there appears to be a connection between an expression of certain behaviors and at least a retrospective mentalistic interpretation of them. However, this connection might reflect the operation of evolutionary innovations peculiar to our species, which now develop alongside more ancestral behaviors that were originally unconnected with an understanding of mental states. Two versions of this possibility exist. First, humans might start off on a different track altogether, so that during each step of cognitive development an interpretative mechanism related to theory of mind allows for a qualitatively different kind of understanding of behavior than that which is present in most other species. In this case, the evolutionary innovation in theory of mind was woven into the early portions of the ancestral cognitive developmental pathways. A second possibility is that the behaviors that Baron-Cohen and others see as evidence that 9-month-old infant humans engage in ‘shared attention’ or ‘intentionality detection’, are in truth supported by no more than clever behavioral algorithms. It might be that rather than meddling with the earliest portions of the shared cognitive pathways of great apes and humans, evolution has woven in a theory-of-mind system at later stages. For example, it is quite compatible with a sceptical view of the developmental literature in this area that human infants must await their second year of life before they develop the evolutionarily novel cognitive structures that allow them to move from a state of ‘mindblindness’ to a vantage point from which they can see the behavior of themselves and others in genuinely mentalistic terms.
Cortex Cerebri. Performance, Structural and Functional Organization of the Cortex by O.D. Creutzfeldt, Oxford Science Publications, 1995. £65.00 (xiv + 658 pages) ISBN 0 19 852324 6 I remember clearly when Otto Creutzfeldt showed me his newly completed edition of Cortex Cerebri, in what must have been 1983. That was, of course, the original German version, and I remember suggesting that an English version would be a sure 300
TINS Vol. 19, No. 7, 1996
success. I did not know that an English version was almost ready in 1985, as Mary Creutzfeldt tells us in her Preface to this, that finally finished version. In the early 1980s this book represented a superb account of what we knew
Much of what we have said is compatible with many of Baron-Cohen’s ideas. However, this view does mean that we need to seriously rethink the evolutionary approach Baron-Cohen adopts to the problem at hand. Evolution will be of very little heuristic help if we are content to say, ‘it exists, therefore it must have evolved.’ If theory of mind is largely absent in such social species as chimpanzees and other non-human primates, then what does the Machiavellian Intelligence hypothesis really contribute to our understanding of the evolutionary history of mindreading? For that matter, even if our ongoing research ultimately reveals aspects of a limited mindreading system in chimpanzees, what about the many other social mammals and insects for whom the ‘contingency stance’ might work just fine? To be sure, we can imagine how theory of mind might be useful in social situations, but if most social organisms have no theory of mind then how can we offer sociality as an explanation for its evolution? Exactly how social a creature need you be to evolve SAM or ToMM? What is it about group-living per se that has driven the evolution of various aspects of theory of mind? Although Baron-Cohen certainly does not purport to answer these questions, his fascinating excursion certainly sets the stage for asking them. Daniel J. Povinelli Theodore J. Povinelli Laboratory of Comparative Behavioral Biology, University of Southwestern Louisiana New Iberia Research Center, 4401 West Admiral Doyle Drive, New Iberia, LA 70501, USA. References 1 Fodor, J. (1983) The Modularity of Mind, MIT Press 2 Baron-Cohen, S., Leslie, A. and Frith, U. (1985) Cognition 21, 37– 46 3 Povinelli, D.J. and Preuss, T.M. (1995) Trends Neurosci. 18, 418– 424 4 Povinelli, D.J. and Eddy, T.J. (1996) Monogr. Soc. Res. Child Dev. 61 (3, Serial No. 247) 5 Povinelli, D.J. and Eddy, T.J. Psychol. Sci. (in press) 6 de Waal, F.B.M. (1982) Chimpanzee Politics, Harper and Row 7 Tomasello, M. and Call, J. (1994) Yearbook Phys. Anthropol. 37, 273–305
about the cerebral cortex, and it is a pity that it was inaccessible to most, unless their German was adequate. Otto Creutzfeldt himself contributed so much to that fount of knowledge, and his students and their students are now continuing that tradition. Although he was internationally renowned for his single-unit electrophysiological studies on the mammalian visual system, including the cortex, his collaboration with others, including even anatomists, ensured that he had a
Copyright © 1996, Elsevier Science Ltd. All rights reserved. 0166 - 2236/96/$15.00
PII: S0166-2236(96)60018-6
specification in the human brain from two completely different viewpoints, and constitute short and excellent syntheses of their own works on this topic. This book has a refreshing excitement to it, and infinite other possible approaches to this study have yet to be elucidated. I would therefore strongly recommend it to readers working in one of the fields covered here.
1 Falk, D. (1990) Behav. Brain Sci. 13, 333–381 2 Clutton-Brock, T.H. and Harvey, P.H. (1980) J. Zool. 190, 309–323 3 Martin, R.W. (1983) Fifty-second James Arthur Lecture on the Evolution of the Human Brain, Am. Museum Nat. History 4 Tishkoff, S.A. et al. (1996) Science 271, 1380 –1387 5 Allman, J. (1990) in Cerebral Cortex (Vol. 8A) ( Jones, E.G. and Peters, A., eds), pp. 269–283, Plenum Publishing Corporation 6 Pinker, S. and Bloom, P. (1990) Behav. Brain Sci. 13, 707–784 7 Schull, J. (1990) Behav. Brain Sci. 13, 63–108
Emmanuel Gilissen Division of Biology, Caltech 216-76, Pasadena, CA 91125, USA.
Mindblindness. An Essay on Autism and Theory of Mind by Simon Baron-Cohen, MIT Press, 1995. £17.95 (xxii + 171 pages) ISBN 0 262 02384 9 Blind to mind? It rhymes, and perhaps exactly such a poetic query might occur to those unfamiliar with the field of ‘theory of mind’ who find themselves thumbing through Baron-Cohen’s Mindblindness. After all, it is an especially intriguing book in which developmental pathologies, evolutionary scenarios, studies of the social intelligence of chimpanzees and children, and lines from Shakespeare, Emerson, Shelley and Byron, are all woven together into an account of the development and evolution of humanity’s most puzzling cognitive achievement – our ability to make inferences about the unobservable mental lives of ourselves and those around us. Baron-Cohen presents a model in which four purported brain modules interact to produce the human ‘mindreading’ system – our ability to represent and reason about the inner mental states of ourselves and others. The intellectual motivation for characterizing the mindreading system in terms of modules derives from Jerry Fodor’s1 resurrection of separate brain mechanisms, each relatively independent of the other, serving specific functions. In the spirit of Alan Leslie and David Premack, Baron-Cohen offers his own list of four prepackaged theory-of-mind brain modules, each performing specialized computations which ultimately interact to produce the human mindreading system: an Intentionality Detector (ID), an Eye Direction Detector (EDD), a Shared Attention Mechanism (SAM), and a Theory of Mind Mechanism (ToMM). First, ID is envisioned as a hardwired perceptual device which interprets moving stimuli in terms of desires and goals. In parallel, EDD is envisioned as detecting the presence and direction of eyes, and also interprets gaze as ‘seeing’ (does she see that?). Both ID and EDD produce inputs into SAM, which is envisioned as forming relationships among the self,
References
other agents and objects (do you and I see the same thing?). Finally, ToMM is seen as unifying the separate notions of attention, desire, intention, and knowledge and belief, into a coherent theoretical apparatus for understanding behavior in mentalistic terms – a theory of mind. If everyday humans are mindreaders, then who are the ‘mindblind’ to which the title of Baron-Cohen’s essay refers? Baron-Cohen proposes that the syndrome of autism might be characterized in exactly this manner: mindblindness. In the early 1980s, Baron-Cohen was among the first to propose that the cognitive development of autistic persons might be very different from that of normal children; in short, they might possess a profound dysfunction in theory of mind2. Autistic persons might, to a large extent, be unaware of the existence of many of the mental states that we take for granted. Much of Baron-Cohen’s book is devoted to reviewing his and others’ innovative work investigating theory-ofmind limitations in autistic persons, and in speculating on how different subgroups of autism might be the result of slightly different impairments in various modules of his hypothesized mindreading system. Baron-Cohen’s book is fascinating and far-reaching, but we wish to focus on a recurring theme of his essay concerning the evolution of theory of mind. On the surface, his account of the evolution of the mindreading system seems plausible. Evolution has designed the component brain modules that social creatures need to navigate their way through the complex social milieu of group-living. For example, throughout Chapter 3, Baron-Cohen turns to the Machiavellian Intelligence hypothesis (originally espoused by Alison Jolly in the mid-1960s) as an appropriate way of thinking about the evolution of the mindreading system. Here, it is the social complexity of group-living that has created a
Copyright © 1996, Elsevier Science Ltd. All rights reserved. 0166 - 2236/96/$15.00
selective context for favoring animals that possessed intellectual structures capable of coping with the daily ins and outs of being part of a social community, and ultimately, according to Baron-Cohen, the mindreading system. Just imagine what an advantage it would be, Baron-Cohen prods us, if you could anticipate what your rivals were likely to do next. And what better way of anticipating their next move, than to assess their inner mental states? Who is she paying attention to? What does he want? What does she know? To BaronCohen the implications are obvious: ‘The lack of competitive alternatives to mindreading that could produce equal or better success…makes it clearer why natural selection might have latched onto mindreading as an adaptive solution to the problem of predicting behavior and sharing information’ (p. 30). Without debating the potential utility of theory of mind in a social context, let us sketch a very different picture of the evolution of this cognitive system that is emerging from our research comparing theory-of-mind development in young children and its expression (or lack thereof) in chimpanzees. Take the case of gaze-following, which Baron-Cohen uses as evidence of the presence of EDD in human infants. He notes that by nine months or so children begin following the line-of-sight of others. By 18 months this behavior is well consolidated. Just look behind a 2-year-old and watch them spin around as if to check to see what you are looking at. But, as he notes, our research shows that this sight gag works equally well with chimpanzees3–5. On the one hand, we might have no problem with this. Chimpanzees are highly social creatures who are Machiavellian beasts par excellance: they gaze into each others’ eyes as if to extract meaning, and ‘manipulate’ and ‘deceive’ their way through highly competitive social situations6. Therefore, in the context of their gaze-following abilities, why not just grant them an understanding of the intentionality of ‘seeing’? The problem is that comparative work with chimpanzees and
PII: S0166-2236(96)60013-7
TINS Vol. 19, No. 7, 1996
299
R E V I E WS
B OO K
R EV I EWS young children reveals that, whereas human toddlers and preschoolers seem to develop a system for interpreting each others’ (and their own) behavior in mentalistic ways, chimpanzees might be doing neither3–5,7. Thus, although chimpanzees are masters at using each others’ gaze to discover things not in their immediate visual field, every method we have developed to ask them, do you understand that vision is about (or refers to) something?, they have unselfconsciously replied, ‘no’3. This discovery of an apparent dissociation between sophisticated gazefollowing and an appreciation of the mental state of attention behind gaze, raises troubling questions. On the one hand, it raises the question of whether the behaviors Baron-Cohen cites as evidence of shared attention in 9- to 18-month-olds (that is, pointing, gaze-following, gaze-alternation), are really an indication of an understanding of the mental state of attention. If apes follow your gaze without appreciating the attentional states behind it, so too might human infants. However, it is possible that we need to be prepared to think differently about certain behaviors depending on whether apes or human infants are displaying them. Perhaps when apes engage in ‘shared attention’ behaviors they do not understand them in a mentalistic fashion, but when human infants engage in the exact same behaviors they do. Before we are attacked for creating a double-standard, consider the following. Might it not be the case that gaze-following, deception, and the like are fairly ancient behavioral mechanisms which evolved long before anything like SAM or ToMM were in place? Perhaps it is our species alone that has specialized in representing each other’s mental states, and in doing so have been placed in the unique position of being able to reinterpret ancestral behavioral patterns, which evolved long before humans appeared on the scene3. For example, after following someone’s gaze, when is it, exactly, that humans wonder what it is they are looking at? Does our behavior follow from the mentalistic query, or is it exactly the reverse? We suspect that much of the social value of theory of mind occurs in
exactly this retrospective way – as a means for planning future social action, not as a means of solving on-line social problems. To put the point directly, whereas BaronCohen (and others) tend to describe social creatures as needing a powerful theory of mind in the thick of social situations (pp. 23–30), we envision nearly the opposite: what they need most is a means of quickly selecting the appropriate behavioral script in order to act rapidly. Theory of mind is an added bonus. Thus, in humans there appears to be a connection between an expression of certain behaviors and at least a retrospective mentalistic interpretation of them. However, this connection might reflect the operation of evolutionary innovations peculiar to our species, which now develop alongside more ancestral behaviors that were originally unconnected with an understanding of mental states. Two versions of this possibility exist. First, humans might start off on a different track altogether, so that during each step of cognitive development an interpretative mechanism related to theory of mind allows for a qualitatively different kind of understanding of behavior than that which is present in most other species. In this case, the evolutionary innovation in theory of mind was woven into the early portions of the ancestral cognitive developmental pathways. A second possibility is that the behaviors that Baron-Cohen and others see as evidence that 9-month-old infant humans engage in ‘shared attention’ or ‘intentionality detection’, are in truth supported by no more than clever behavioral algorithms. It might be that rather than meddling with the earliest portions of the shared cognitive pathways of great apes and humans, evolution has woven in a theory-of-mind system at later stages. For example, it is quite compatible with a sceptical view of the developmental literature in this area that human infants must await their second year of life before they develop the evolutionarily novel cognitive structures that allow them to move from a state of ‘mindblindness’ to a vantage point from which they can see the behavior of themselves and others in genuinely mentalistic terms.
Cortex Cerebri. Performance, Structural and Functional Organization of the Cortex by O.D. Creutzfeldt, Oxford Science Publications, 1995. £65.00 (xiv + 658 pages) ISBN 0 19 852324 6 I remember clearly when Otto Creutzfeldt showed me his newly completed edition of Cortex Cerebri, in what must have been 1983. That was, of course, the original German version, and I remember suggesting that an English version would be a sure 300
TINS Vol. 19, No. 7, 1996
success. I did not know that an English version was almost ready in 1985, as Mary Creutzfeldt tells us in her Preface to this, that finally finished version. In the early 1980s this book represented a superb account of what we knew
Much of what we have said is compatible with many of Baron-Cohen’s ideas. However, this view does mean that we need to seriously rethink the evolutionary approach Baron-Cohen adopts to the problem at hand. Evolution will be of very little heuristic help if we are content to say, ‘it exists, therefore it must have evolved.’ If theory of mind is largely absent in such social species as chimpanzees and other non-human primates, then what does the Machiavellian Intelligence hypothesis really contribute to our understanding of the evolutionary history of mindreading? For that matter, even if our ongoing research ultimately reveals aspects of a limited mindreading system in chimpanzees, what about the many other social mammals and insects for whom the ‘contingency stance’ might work just fine? To be sure, we can imagine how theory of mind might be useful in social situations, but if most social organisms have no theory of mind then how can we offer sociality as an explanation for its evolution? Exactly how social a creature need you be to evolve SAM or ToMM? What is it about group-living per se that has driven the evolution of various aspects of theory of mind? Although Baron-Cohen certainly does not purport to answer these questions, his fascinating excursion certainly sets the stage for asking them. Daniel J. Povinelli Theodore J. Povinelli Laboratory of Comparative Behavioral Biology, University of Southwestern Louisiana New Iberia Research Center, 4401 West Admiral Doyle Drive, New Iberia, LA 70501, USA. References 1 Fodor, J. (1983) The Modularity of Mind, MIT Press 2 Baron-Cohen, S., Leslie, A. and Frith, U. (1985) Cognition 21, 37– 46 3 Povinelli, D.J. and Preuss, T.M. (1995) Trends Neurosci. 18, 418– 424 4 Povinelli, D.J. and Eddy, T.J. (1996) Monogr. Soc. Res. Child Dev. 61 (3, Serial No. 247) 5 Povinelli, D.J. and Eddy, T.J. Psychol. Sci. (in press) 6 de Waal, F.B.M. (1982) Chimpanzee Politics, Harper and Row 7 Tomasello, M. and Call, J. (1994) Yearbook Phys. Anthropol. 37, 273–305
about the cerebral cortex, and it is a pity that it was inaccessible to most, unless their German was adequate. Otto Creutzfeldt himself contributed so much to that fount of knowledge, and his students and their students are now continuing that tradition. Although he was internationally renowned for his single-unit electrophysiological studies on the mammalian visual system, including the cortex, his collaboration with others, including even anatomists, ensured that he had a
Copyright © 1996, Elsevier Science Ltd. All rights reserved. 0166 - 2236/96/$15.00
PII: S0166-2236(96)60018-6