AI Magazine Volume 13 Number 2 (1992) (© AAAI) Book Reviews BookReviews

Neurons, , cussion of viewpoint in the novel! machinery is identified in the brain, Further, the essays themselves stay less and less space is left for general- and Communication firmly within the territory of the purpose computation. authors’ expertise: They are either In “What Does the Brain See? How Philip Swarm overviews of the state of the art or a Does It Understand?” Horace Barlow Images and Understanding: Thoughts piece of work in progress at the time presents the anatomy of the brain, about Images, Ideas about Understand- of invitation. I found that the only visual pathways, cortical maps, and ing, H. Barlow, C. Blakemore, and M. way to make of the volume was the structure of receptive fields for Weston-Smith, eds., A collection of to deconstruct it and reassemble the individual neurons. This system essays based on a Rank Prize Fund’s essays according to their original dis- transforms the raw image projected International Symposium, organized ciplines, hence my title and the order onto the retina into a cortical image with the help of Jonathan Miller and that I follow in this review. The stated that has been filtered and restruc- held at the Royal Society in October interdisciplinary claims of the editors tured in many ways. However, as it is 1986, Cambridge University Press, are further weakened by the absence held in the primary visual cortex, this Cambridge, United Kingdom, 1990, of discussion among the participants image is still largely a meaningless 401 pp., ISBN O-521-34177-9 (cloth), themselves; they do not even say if bitwise representation. How does the ISBN O-521-36944-4 (paper). such discussion took place. There- brain find objects and relations in fore, it is left to the reader to judge if the image (rather, in sequences of This volume is a well-written, infor- the whole is greater than its parts, images), or as Barlow puts it, how mative, and thought-provoking col- which is what I try do in this review. does the brain understand what it lection of essays that should interest sees? It is a measure of progress made anyone concerned with the Neurons that this question no longer seems of vision and visual communication. silly, and Barlow’s answer seems plau- The aim of the original symposium Starting with the pioneering (and sible. He suggests that the cells in the was to bring together people from Nobel Prize-winning) work of David primary visual cortex “grow into the arts and sciences who could pre- Hubel and Tosten Wiesel, neurobiol- other cortical areas where they create sent different perspectives on the ogists have made remarkable progress new patterns in which the informa- subject of images and understanding. in uncovering the structure and func- tion is brought together according to The result is an informal tour con- tion of the visual system in higher new principles that are not necessari- ducted by leading specialists (pre- animals. The results of this work ly related to the topography of the dominantly British) that visits both have important implications for our original image” (p. 21). Thus, the pri- famous scientific battlefields and understanding of the brain as a whole. mary area carries out local feature quaint artistic backwaters. Numerous Writing in this collection, Colin detection by way of selective sensitiv- striking pictures enliven the book: Blakemore quotes the steering com- ity to texture, motion, and so on, but Here you can find the sensory somat- mittee of the 1986 Systems Develop- these secondary areas synthesize new ic cortex of a bat, the British miners’ ment Foundation Symposium on higher-level images according to leader Arthur Scargill in full rant, a Computational Neuroscience. The Gestalt-type principles. notation for ballet, a mole used to question under consideration is as Blakemore (“Understanding advertise British Gas, instructions for follows: Is physical locality an essen- Images in the Brain”) tackles the dif- righting a caravan, and many others. tial part of neural computation? ficult question of functional interpre- The 23 essays originated in diverse According to position 1, “Brain func- tation in a way that complements disciplines, among them biology, tion is determined by the logical and Barlow’s presentation. He points out psychology, art history, and linguis- dynamic connection properties of its that just because cells in the visual tics. They are grouped according to neurons. The actual physical struc- cortex are laid out as isomorphic the sessions in which they were pre- ture, location, architecture, and maps of the sensory cells in the sented under thematic titles: The geometry is irrelevant to its logical, retina, it does not follow that the Essence of Images, Movement, Narra- connectionist aspects.” In contrast, brain actually uses the information tion, Making Images, Images and for position 2, the anatomical struc- provided by the map (as opposed to Thought, and Images and Meaning. ture of the brain “may represent a the information carried by the indi- However, the desire to have a good major mode of brain function: the vidual cells and their connections). interdisciplinary mix in each session formatting of sensory data in a Indeed, the maps might be a simple renders the already generic session manner which simplifies its further artifact: “an inevitable but useless titles meaningless; for example, John processing” (p. 262). The neurobio- consequence of the fact that nerve Krebs’s contribution on animal lan- logical contributions in this collec- fibres, growing from the sense organs guage is included in the Narration tion all strongly support position 2: to their targets in the brain, tend to session following David Lodge’s dis- As more and more special-purpose preserve the same spatial pattern as SUMMER 1992 97 that of the receptors in the sense principles proposed by Barlow and (p. 107). organ” (p. 267). In other words, rear- Blakemore. David Perret and his co- Although the neurological work ranging the cortical cells in a random authors in “Three Stages in the Clas- has obtained the most spectacular pattern, while maintaining their con- sification of Body Movements by results, evolutionary biologists are nections, would have no effect on Visual Neurons” offer a superb also working on the visual system. In the information carried: Such a prop- demonstration of what the monkey “Tricks of Colour,” John Mollon erty would be characteristic of a con- brain can achieve at the higher levels begins with the instructive history of nectionist model of the brain. of visual processing. They have the theory of color vision. It was the Blakemore is not a connectionist, recorded the response of individual polymath Thomas Young who point- and he offers several lines of argu- neurons in the temporal cortex to ed out in 1801 that trichromacy is a ment to show that the information various kinds of visual stimuli. It property of our visual system, not in the spatial patterns of neurons in turns out that neurons in this area the physical world; he even guessed the cortex is actually used by the are selective for specific kinds of correctly that there are just three brain. His first argument is that there objects, movements, and events; in classes of receptor cell in the retina are cortical maps that are not isomor- other words, visual knowledge is hard tuned to select for specific subranges phic. Edge-detecting cells in the visual wired. By studying the responses of (blue, green, and red) of the visible cortex are one example. Together with hundreds of such cells, the authors spectrum. Recent work has shown the functional connections between established some of the main subpop- that the biology of the color visual maps, this is strong evidence that the ulations. They found that there are system is even more surprising than brain is interpreting the maps them- cells selective for the six canonical its structure: Asymmetries in the selves as well as their constituents. translations in three dimensions (3- trichromatic system suggest that “our Blakemore’s second line of argu- D) and point out that at least in colour vision depends on two rather ment appeals to biological design English, we have names for them and different subsystems, one recently constraints. First, he suggests that only them (up, down, left, right, overlaid on the other” (p. 67). The maps arise naturally from the low- toward, and away). Similarly, there ancient system is dichromatic (blue, level structure of the brain: “Most of are cells selective for one of the six green) and is found in most mam- the connections in the brain are orthogonal views of the head: “Thus mals and some other lower animals; short, local fibres, such that cells are information about body view and it is insensitive to spatial detail and either excited or inhibited by their direction of motion appears to be provides almost purely chromatic close neighbours” (p. 276). Second, segregated into channels of process- information. The more recent trichro- Blakemore claims that topographic ing which use the same three-axes matic system, found in humans and maps facilitate the process of putting system” (p. 96). other Old World primates, is appar- maps together into higher-level struc- Further investigation is revealing ently the result of a duplication of tures. Third, he argues that the genet- even higher levels of specialization. the gene that coded the long-wave- ic specification for building the brain The authors have strong evidence length pigment (green) in the ancient must be small, so the procedural rules that although most neurons are selec- system. Further, the new dimension are likely to be simple; for example, tive according to the viewer’s frame of color is parasitic on an edge- “Make all nerve cells inhibit their of reference, others actually respond detecting system of cells and, conse- immediate neighbors on either side” with respect to an actor- or object- quently, is sensitive to spatial detail. (p. 278). Theoretical models have centered frame of reference! They Other recent research has elucidated shown that such simple rules for exhibit one such cell that responds to the genetic mechanisms that give rise local interaction will replicate the arm movements that bring the hand to the various types of color blind- properties of real nerve cells, provid- in front of the face independent of ness, and Mollon concludes with ed that the input to the network is the orientation of the actor with some astonishing results concerning topographically arranged. The con- respect to the viewer. Finally, other the mothers of color-blind men. It is clusion is that the infrastructure of cells are sensitive to goal-directed apparently possible that some of the brain might well be similar or actions, for example, an actor walking these carriers are actually tetrachro- even identical throughout the cortex: toward the door of the laboratory. matic and, thus, enjoy an extra Local functional specialization would Moreover, the visual understanding dimension of color discrimination! be achieved by the nature of the encoded by such cells does not directly input and their topographic distribu- cause motor or emotional reactions: Perception tion. In one of the most interesting An actor leaving the laboratory results points made in the whole book, in different behavioral responses, What is the relation between our Blakemore notes that the enormous depending on the circumstances, for everyday subjective experience of the increase in the size of the mam- the same visual neuron response. As visual world and the rapidly develop- malian brain appears to be owed pri- the authors point out, cognitive sci- ing scientific knowledge concerning marily to the addition of more and entists do not usually admit such the neurobiological medium of this more sensory areas; he remarks ironi- goal-centered descriptions as a part of experience? In other words, are we cally that higher intelligence might vision: “Understanding of actions is any closer to seeing how the brain thus be a consequence of an increase seen as requiring logical inference can be a mind-and vice versa? The in perceptual resources rather than based on previous experience. This neurobiologists contributing to this symbolic computational power. attitude ignores the fact that the collection do some hand waving in The remaining neurobiological database and processing from which the direction of these questions, but essays describe work on the function a comprehension of actions can be the substance of their contribution of neural subsystems that provides made, can be purely visual and does regards the science of brain function. supporting evidence for the general not necessitate the use of language” The rapid emergence of this new sci- 98 AI MAGAZINE ence has, I think, rather caught psy- ing perception. Illusory surfaces and with his famous experiments on chologists and philosophers who contours, such as those seen in the mental rotations, replies to Good- deal with such issues off guard, an Kanizsa triangle, are rather different, man. He agrees that we have to be impression that is confirmed by their and Gregory’s discussion is not easy careful about the vocabulary, but contributions to this collection. to follow. He apparently suggests that don’t really get into trouble if we With Richard Gregory’s piece these ghostly surfaces are a kind of remember that “mental imagery is of “How Do We Interpret Images?” the limited case of the general subjective external objects, and is therefore to discussion moves to the psychologi- phenomenon of object completion; be defined and studied not as some cal level of : “The for example, a car parked behind a strange, non-material ‘picture in the key problem for perception is how lamp post is not perceived as a car head’ but in relation to potential test meaning is read from neural signals with a vertical slice missing! Evidence stimuli that are both external and from the ” (p. 310). The senses that the illusory surfaces are algovis- physical” (p. 370). Finally, in a fasci- of touch, taste, or smell can directly tic rather than knowledge based is nating historical survey, “Scientific signal biologically significant stimuli not hard to find. First, the surfaces Images: Perception and Deception,” such as heat, cold, and food. In con- apparently require contours that are Jon Darius shows how scientists are trast, images are only representations the completion of simple, smooth frequently led to see what they want of stimuli: They have to be interpret- curves. Second, Gregory and others to see in visual images, prejudiced by ed before meaningful action can have shown that the illusion is gen- their theories and beliefs. Here, how- follow, and it is this interpretation erated early in the visual system, in ever, “seeing” refers to the entire pro- that delivers perception from sensa- some cases before stereo fusion, and, cess of interpretation with respect to tion, thus the initial meaning of the thus, prior to higher-level cognitive sociocultural context; thus, it lies image. With respect to this process of processing. Finally, “a disturbing fea- largely beyond the ken of current interpretation, Gregory characterizes ture of all illusions is that we can be psychology and neurology. the two main schools of thought in perceptually illuded [sic] while at the the theory of perception as passivist same time knowing this-so we are and activist, James Gibson and Her- not conceptually deluded” (p. 329). Computer-Generated Images mann Helmholtz being, respectively, Gregory concludes with some perhaps the best-known exponents speculations regarding the relative Work on the manipulation of images of each school. The distinction is independence of perception and con- by computers is of two main types: slippery to say the least but is fairly ception. First, if what we perceived In computer graphics, the goal is to clear in its most extreme form: The was dependent on what we know, produce an image from a mathemati- passivists hold that perception is an then it would be impossible to see cal model, but in computer vision, almost direct grasping of sense data, anything new. Second, it would be the goal is to extract a mathematical but a radical activist treats visual per- vastly redundant and biologically model from a given image. For exam- ception as functionally similar to lan- costly (or impossible) to check every- ple, given the equation for a curve, guage understanding. Thus, the thing we see against everything we we can program a computer to draw activist will favor a top-down style of know. Finally, Gregory says, “When the curve on screen or paper, but analysis in which knowledge and we study illusory contours and ghost- given a bit image of a curve, we can expectation drive perception, with ly surfaces, we see what we know is try to solve the much harder problem visual illusions offering decisive sup- illusion. Could this separation of finding the equation that best fits porting evidence. The line of research between perception and conception it. An easily drawn analogy between started by David Marr might at first be the distinction between ‘subjec- computer vision and human vision sight be considered passivist, but tive’ and ‘objective’, and so divide art has led to a certain exchange of ideas Gregory suggests that workers in this and science, so that we live with two between the two fields. Some cogni- area really belong to a third school, kinds of meanings?” (p. 330). tive scientists have taken the analogy the algovists, occupying a middle Three other contributions deal seriously and claimed that at some position. AZgovists differ from tradi- with higher-level aspects of perception. level of abstraction, the brain is solv- tional activists in that they empha- In a disappointing piece, “Pictures in ing the same problem using the same size abstract formal properties of the the Mind?” Nelson Goodman issues methods as the computer; so, a theory image, such as the laws of perspec- the familiar philosophical warnings of human vision can be tested by tive, rather than specific knowledge about mental imagery, recalling the implementing it as a program. of objects. long-running debate in the cognitive Three essays in the collection dis- At first, the distinction between science community over Stephen cuss computer-generated images. the algovist and activist approaches Kosslyn’s work. It is apparently dan- Andrew Witkin et al., “Linking Per- might seem vague and unworkable, gerous to speak loosely of mental ception and Graphics: Modeling with but in the second half of his essay images or pictures because “having Dynamic Constraints,” present a Gregory shows how it can be made an image amounts not to possessing nontechnical view of some recent operational in the experimental some immaterial picture in some- work in building mathematical study of visual illusions. Take, for thing called a mind but to having models of objects in the physical example, Rubin’s classic faces-vase and exercizing [sic] certain skills-a world. Lansdown’s “Understanding figure. A person who had seen faces matter of producing, judging, reviz- the Digital Image” is an equally non- but had never seen a vase would ing [sic] certain material pictures and technical description of the ray- presumably not see the figure as descriptions” (p. 362). In a postscript tracing techniques used to give com- ambiguous. This case is a clear-cut entitled “On Understanding Mental putational representations of 3-D example of acquired knowledge Images,” Roger Shepard, who made scenes. Neither of these contribu- about specific object types determin- mental imagery respectable again tions suggests connections between SUMMER 1992 99 Book Reviews

their work and human perception. almost solely with conceptual analy- In “Computer-Generated Car- sis, attempt to elucidate general prin- toons,” Andrew Pearson, E. Hanna, ciples and mechanisms at work in all and K. Martinez do argue for such forms of communication. Whatever connections. They developed soft- its cultural value, semiotics has so far ware that will extract a digital line yielded little of scientific interest. drawing (a cartoon) from a photo- This failure might be because the graph. The goal is to produce a arbitrary and conventional character system that can create moving car- of cultural systems excludes them toons from video and transmit them from the domain of science, or it across data networks; this technique might be because real progress in would allow, for example, the deaf semiotics can only follow from Innovative Applications to communicate by sign language progress in neuropsychology. This through a telephone line. The statement is the working assumption of Artificial Intelligence authors found quickly that simple of some neuropsychologists, explicitly two-dimensional edge detection was stated by Barlow: “This book is being edited by Herbert Schorr and unsatisfactory and hypothesized published in the belief that an instead that cartoon lines should cor- account of what goes on inside the Alain Rappaport respond to the 3-D points where lines skull is relevant for those who are from the camera or eye were tangent mainly concerned with the external All of the contributions in this to the surface of the human face in world, and that the latter group have book have a practical slant, the image. An analysis of the way [sic] knowledge of the ways that showing how AI has been suc- light falls on faces showed that the images are linked, connected, and loci of these tangent points lay in meaningfully manipulated that can cessfully applied to a wide luminous valleys or at step edges, aid scientific understanding of the spectrum of domains and allowing the authors to design a mysteries of the mind” (p. 25). tasks. They provide an excel- detector that could extract the loci as Despite this pious hope, the con- lent sampling of the types of lines from a digitized photograph. ceptual apparatus of the two groups applications coming on line. The result is remarkably effective and is completely disjoint, and there are compares favorably with cartoons no clear connections between them. Systems architectures and produced by a human artist from the That said, the contributors provide development strategies are same photographs. an interesting anthology of the data addressed along with tactical The cartoons generated by the and styles of analysis used in semi- issues, payback data, and real system of Pearson and his colleagues otics and the humanities. Ernst Gom- benefits. have a remarkable property: If they brich gives a history of pictorial are passed through the system a instructions, from sixteenth-century second time, they do not change. The fencing manuals to airline safety Featuring applications in: authors also note that their detector leaflets. Monica Parker and Kenneth MacMillan present “Benesh: The l Aerospace is functionally similar to known low- level neural filters in the retina and Notation of Dance,” a shorthand that l Banking and Finance visual cortex. In addition, there are can record the complexities of classi- l Media clear connections with “Marr’s idea cal ballet. In “What Does Gesture of a ‘raw primal sketch’ as a first pro- Add to the Spoken Word?” Peter Bull l Music cessing step in the representation of gives a fascinating analysis of the use l Military shape information in the human of gesture in political speech making. l Operations Management visual system” (p. 55). These and With a careful study of a video, Bull other considerations led the authors shows how Arthur Scargill’s verbal l Personnel Management to claim that the computer and car- rhetoric is accompanied by gestures l Retail Packaging toonist essentially replicate the work that control the audience’s applause; of the first stage of human visual pro- thus, he “creates the impression of References,index, 300 pp. cessing. Thus, the cartoon will set up overwhelming popularity, continual- the same response in the early visual ly struggling to make his message $24.50, ISBN O-262-69137-X system as the photograph from audible both by speaking into the which it was extracted! applause and by using gestures to Published by the restrain it” (p. 119). In “Are the Signs MAI Pressand The MIT Press of Language Arbitrary?” Margaret Visual Communication Deuchar concludes, rather confusingly, Most of the remaining contributions that they are in fact conventional, To order, call toll-free to the symposium come from the arts which is surely what linguists mean l-800-356-0343 or and humanities. Viewed as science, by arbitrary. Lodge’s piece, “Narra- (617) 6258569 they can loosely be classified as deal- tion,” gives the literary critic’s under- Fax orders: (617) 625-6660 ing with semiotics. If the neuropsy- standing of viewpoint in story telling, chologists work bottom up, the and John Willats’s “The Draughts- Mastercard and VISA accepted. semioticians are resolutely top down. man’s Contract: How an Artist Cre- They start with human communication ates an Image,” provides analogous in its full complexity and, armed comments regarding representational 100 AI MAGAZINE Book Reviews conventions in drawing. ple, it is to the advantage of dog B to audience and the occasion, I think, More hope for genuine interdisci- anticipate a bite from dog A by eva- in fact, that it genuinely reflects the plinary progress surely lies initially sively responding to A’s tooth baring. contributors’ views on the state of in the study of visual signals used for However, now A can force B to take the art. Further, this low-key, prag- communication by animals. Such sig- evasive action simply by baring its matic approach has a lot to recom- nals mark the boundary between the teeth! It is at this point that tooth mend it. The style comes from tightly constrained world of neuro- baring has become a genuine signal; biology rather than cognitive sci- logical visual processing and the indeed, Krebs defines signals as ence, and the emphasis is on the unconstrained world of conventional “behaviour patterns used by actors to phenomena themselves rather than symbolic systems created by human manipulate the behaviour of reactors on data, models, and theories. societies. By attacking from both to the advantage of the actor” (p. The book reflects the remarkable sides, we clarify the boundary itself 158). The story doesn’t end there progress made by neuropsychology. and the phenomena it separates. because it is now to B’s advantage to Working from the bottom up, neu- Michael Land’s contribution, “Vision treat the signal as a bluff, which leads rologists have shown that sensory in Other Animals,” deals not with A “to increase the persuasive power processing in the brain is localized communication but rather with the of the signal by, for example, exag- and highly structured into partly optics of vision in three remarkable geration, elaboration, repetition and autonomous subsystems of diverse invertebrates: the scallop, the boat- any other device that might over- evolutionary origin. Working in the man, and the jumping spider. The come sales-resistance” (p. 159). middle, psychologists are beginning spider is famous for its acute eight- A beautiful example of how elabo- to establish how this processing eyed vision, incorporating, for the rate such persuasion can become is structure constrains our visual expe- principal pair of eyes, a movable provided by the Australian satin rience. However, understanding an retina behind the fixed lens. “Like bowerbird. The males of this species image is something that happens our own eyes, each has six eye mus- build complex and decorated bowers right at the top when the conscious, cles, and these move the retina up to attract the females. Mating success reflective self interprets a symbol and down, side to side, and also is directly related to bower showiness: with respect to a language, a culture, cause it to rotate around the visual In one study, the most successful and its own remembered experience. axis” (p. 208). This remarkable male mated 30 times, the least suc- Nothing is said in this book about system is used to detect prey, preda- cessful not at all. Why would females the vast, largely uncharted area of tors, and potential mates. However, succumb to this rather nouveau riche the brain where this interpretation Land does suggest that the complex approach? It turns out that the males happens, where the results of percep- movements of the retina correlate steal each other’s decorations and tion are synthesized into conscious with edge-detecting neurons to facili- sometimes destroy the bower of a experience, translated into action, tate the identification of “conspecifics” rival; so, bower showiness can be and integrated with memory. Fur- by checking for their characteristic read as a measure of the male’s abili- ther, nothing is said-and presum- leggy silhouette: “If we assume that ty to defend and steal and, thus, is a ably little is known-about the way the retinae contain rows of receptors good metric for potential mates. that top-level processes feed knowl- that link up to ‘line detectors’, then In conclusion, Krebs notes that edge back to the visual system to the scanning pattern is understand- from evolutionary continuity, it follows support recognition and learning. able; the rotational movements that animal signals must contain, in Even when the neurologists com- would provide the detectors with a embryonic form, some of the charac- plete their description of the brain’s range of orientations, and the lateral teristics of human communication. functional architecture, any pro- movements can be thought of as However, it is too easy-and nearly posed theory of understanding will hunting for matches between the always wrong-to read such charac- still have to tackle the social and detectors and the contours” (p. 210). teristics back into animal signals. conventional grounding of human The title of Krebs’s essay, “Animal semiotic systems. Language,” leaves no doubt that he Conclusions In strictly scientific terms, then, is discussing communication, but the symposium was premature-per- “animal signals” would have better It will be clear, I think, that the intel- haps by several decades! However, reflected the account he gives. Animal lectual style of this symposium was the approach it took gives some signals, he points out, usually convey far removed from the heated ideolog- interesting pointers to the future of simple messages about immediate ical clashes so characteristic of cogni- cognitive science. First, the account events: Keep out, I am a male, and tive science and AI in the United of the visual system (and by implica- the like. However, many such signals States. Indeed, one might be tempted tion of the brain as a whole) is far have evolved into complex ritualistic to dismiss the book as not being removed from any unified computa- displays, tempting one to assume about the real issues, such as they are tional theory of mind and brain. Our that the original simple message has to be found, for example, in the head apparently contains a loose also become semantically complex. pages of the journal The Behavioral assemblage of hundreds of systems Krebs argues that this assumption, in and Brain Sciences. All the buzzwords put together by evolution at various fact, is not the case, as follows: Before are missing: There is no mention times and places. As biologists recon- animals used signals at all, they inter- here of information processing, sym- struct the origin, purpose, and history acted in various ways that affected bolic computation, neural networks, of these systems, it is becoming their reproductive probabilities. Nat- the modularity of mind, knowledge increasingly difficult to distinguish ural selection would favor individu- representation, and so on. Although the psychological from the biological. als who could anticipate important not including such terms could be Second, several of the essays show actions of their neighbors. For exam- explained as a concession to the the importance of working at the SUMMER 1992 101 Book Reviews

boundaries of domains. For example, gy of singing. The final part, “Force A third recurring problem is also evi- the boundary between simple behav- Sensing and Control,” includes articles denced here: failure to discuss what ioral interactions and actual commu- on grasping, sensing, hand design, types of processing, if any, these rep- nication in lower animals is now a manipulation, motion, and the resentations, the codons, are useful for. tractable problem for neurobiology; geometry and dynamics of walking. Staffan TruvC and Richards present we can hope to learn the evolution- In part 1, Richards explains his an object description language moti- ary mechanisms that took some approach to perception research, vated in part by a superficial analogy species across this boundary. Third, advocating the careful analysis of the to grammars for natural language. the symposium confirms a shift in information-processing tasks of bio- This article investigates the mathe- emphasis away from higher-level cog- logical systems, leading to reasonably matical properties of this and various nitive processes, such as language clean, fairly abstract descriptions of auxiliary representations. This proposal and logic, toward lower-level sensory the solutions. Richards acknowledges is not related to work in solid model- processes such as object recognition. his debt to Marr; indeed, Richards’s ing, nor is there any discussion of what Finally, the book leaves me with the approach appears to have nothing tasks this representation is good for. feeling that we might be seeing the new, although the presentation is too It is ironic that the failings of so beginning of a natural history of the obscure to know for sure. Most of the many of the articles in Natural Com- mind in which the evolutionary articles in the book are, in fact, studies putation-failure to keep the larger assemblage of the brain as a ragbag of of diverse issues using (or inspired task in view, failure to compare alter- ad hoc solutions is rather similar in by) Marr’s methods and vocabulary. native approaches, and failure to spirit to the social and cultural assem- They are, for the most part, written focus on processing-are ones that blage of its higher-level contents! by Richards and his students and col- Marr was careful to avoid. However, leagues. Although many of the articles many of the articles do closely follow Philip Swarm is a researchfellow in the address interesting topics, and some Marr in other respects. Sometimes Department of Psychology and Education propose interesting ideas, most are this approach works well, as in Steven at the University of Geneva. His current disappointing. I focus on a few articles Drucker’s demonstration that it is research is concerned with language that reveal specific recurrent flaws. not possible to recover texture infor- acquisition and its relation to other cogni- Michael Riley addresses the prob- mation by touch unless the finger tive and semiotic systems. lem of detecting peaks in spectral can stroke the surface, but often it cross-sections using the analogy of results in limp mimicry, such as the phonologists interpreting spectro- proposal of a primal sketch for acous- grams of speech. By applying various tic information. filters and experimenting with their Many of the authors seem equipped parameters, he achieves good perfor- with little more than a strong mathe- mance. Unfortunately, spectral inter- matical background and a rigid ver- Natural Computation pretation is not a particularly good sion of Marr’s methodology. The source for insights into speech uninteresting, unconvincing, and Nigel Ward recognition, and the exact location of irrelevant results illustrate that there a peak is not a particularly useful fea- is no real recipe for this type of Natural Computation, Whitman ture to extract for speech understand- research and that there is no substi- Richards, MIT Press, Cambridge, Mas- ing. The problem here of addressing a tute for broad and deep knowledge of sachusetts, 1988, 561 pages, $25.00, microproblem that is irrelevant to the the topic of inquiry. Another irony is ISBN 0-262-6805.5-6. larger task is the book’s first recurring that the strongest articles in the book problem. are not particularly inspired by Marr Natural Computation by Whitman Three articles coauthored by at all. This group includes R. Von der Richards is a collection of research Richards develop the idea of qualita- Heydt et al. on the existence of corti- papers on perception and motor con- tively representing the curvature of cal neurons that respond to illusory trol. It is divided into four main parts blob boundaries with strings of codons contours, Kent Stevens on the inter- plus an introduction. “Image Inter- based on the sign of the derivative. pretation of three-dimensional shape pretation: Information at Contours,” These articles go into great detail on from parallel surface contours, Edwin the first major part, includes work on how to robustly extract codons in the Land and John McCann on recover- edge detection and classification, presence of certain types of noise and ing absolute color and reflectance motion, representation and interpre- some combinatoric analysis of possi- despite variations in illumination, tation of smooth curves, and the ble silhouettes and three-dimensional Alex Pentland on fractal-based inference of three-dimensional shape. shapes. This work is not well related description of surfaces, Marc Raibert “Image Interpretation: Property Tags: to the larger context of vision; indeed, on balance and symmetry in run- Color, 3D Texture, Flow Fields,” part it is not at all clear whether an image ning, and Johan Sundberg on the 2, includes articles on illumination, can reliably be split into blobs. The physiology of singing. Most of the edge classification, image velocity, research discussed here is not com- merit of this book lies in the inclu- texture, computer graphics, and frac- pared with other work, the second sion of these classic articles. tal descriptions. Part 3, “Sound Inter- recurring problem with this book; The reasons for including this par- pretation,” includes work on the there is also no information given to ticular set of articles are not given, representation of acoustic informa- help the reader see how this article however. One striking peculiarity is tion, speech recognition, separation relates to the following one the lack of any exemplar of connec- and location of sounds using two ears, by Michael Brady and Alan Yuille on tionist research despite an otherwise the recognition and interpretation of inferring three-dimensional orienta- broad spectrum of methodologies sounds and music, and the physiolo- tion from two-dimensional contour. (psychological, AI, Gibsonian, general 102 AI MAGAZINE Book Re~Gws systems theory). Given the existence ISBN O-521-42898-4. of systems with impressive perfor- H Ince, D. C., ed. Mechanical Intelli- mance on tasks such as joint motion, gence. New York: Elsevier Science speech recognition, and speech pro- n Astair-91. Frankfurt, Germany: Publishing, 1992. 226 pp. $82.00. duction, connectionism seems clearly Intelligente Logistik Systeme Gmbh. ISBN o-444-88058-5. relevant to natural computation, but n Badiru, Adedeji B. Expert Systems Richards does not even comment on Applications in Engineering and Manu- n Kramer, Glenn A. Solving Geometric why connectionism doesn’t qualify. facturing. Englewood Cliffs, N.J.: Constraint Systems. Cambridge, Mass.: Perhaps this omission is the result of Prentice Hall, 1992. 436 pp. ISBN O- The MIT Press, 1992. 277 pp. ISBN O- an overly strict reading of Marr’s 13-278219-7. 262-11164-O injunction against premature low- n Barwise, Jon; Gawron, Mean Mark; n Lauer, Thomas; Peacock, Eileen; level research. Plotkin, Gordon; and Tutiya, Syun, and Graesser, Arthur. Questions and An editor presenting such an eclec- eds. Situation Theory and Its Applica- Information Systems. Hillsdale, N.J.: tic collection has a special obligation tions, volume 2. Chicago, III.: The Lawrence Erlbaum Publishers, 1992. to give the reader the necessary back- University of Chicago Press, 1992. 374 pp. $69.95 (cloth). $34.50 ground, which, at a minimum, 638 pp. $59.95 (cloth). $26.95 (paper). ISBN O-8058-1019-6. requires an introduction to every (paper). ISBN o-937073-70-9. n Levine, Robert, ed. Formal Gram- article. However, Richards only intro- n Beakley, Brian, and Ludlow, Peter, mar. New York: Oxford University duces the four parts of the book, and eds. The Philosophy of Mind: Classical Press, 1992. 439 pp. $60.00. ISBN O- these introductions are poorly written Problems/Contemporary Issues. Cam- 19-507314-2 (cloth). $32.50. ISBN O- and unfocused. There is a glossary, bridge, Mass.: The MIT Press, 1992. 19-507310-X (paper). which helps, but it does not cover 433 pp. $19.95 (paper). $39.95 n Norvig, Peter. Paradigms of Artifi- half of the technical terms intro- (cloth). ISBN O-262-52167-9. cial Intelligence Programming: Case duced. The lack of historical back- n Blanchard, David; and Beard, Paul. Studies in Common Lisp. San Mateo, ground and adequate pointers to Intelligent Applications. Atlanta: Lion- Calif.: Morgan Kaufmann, 1991. 900 more recent developments in the heart Publishing, 1991. 170 pp. pp. $39.95 (book). ISBN l-55860- field makes it difficult to understand $39.95. ISBN 0-962-92170-x 191-0. $54.95 (MACINTOSH or DOS the significance of some articles. diskette). ISBN l-55860-230-5. n Brachman, Ronald J.; Levesque, Physically, the book is a fairly Hector J.; and Reiter, Raymond, eds. n Quantrile, Thomas, and Liu, Y. A. durable paperback with a nice uni- Artificial Intelligence in Chemical Engi- form layout. Unfortunately, so many Knowledge Representation. Cambridge, MA: The MIT Press, 1992. 408 pp. neering. San Diego, Calif.: Academic errors were introduced in the conver- $29.00. ISBN O-262-52168-7. Press, 1992. 609 pp. $75.00 ISBN O- sion process (typographical errors, 12-569550-o. wrong references to numbers of parts n Burnod, Y. An Adaptive Neural Net- and figures, poorly reproduced fig- work: The CerebraI Cortex. Englewood n Ryan, Marie-Laure. Possible Worlds, ures, and even missing text and refer- Cliffs, N.J.: Prentice Hall, 1992. 367 Artificial Intelligence, and Narrative Theory. Bloomington, Ind.: Indiana ences) that it might have been better pp. ISBN o-13-019463-6. University Press, 1992. 320 pp. to just photocopy the original arti- n Chorafas, Dimitris N. Expert Sys- $35.00 (cloth). ISBN o-253-35004-2. cles. The author and subject indexes tems in Manufacturing. New York: Van are thorough, and there are 110 Nostrand Reinhold, 1992. $49.95. n Terano, Toshiro. Fuzzy Systems problems in natural computation at ISBN o-442-00827-9. Theory and Its Applications. San Diego, Calif.: Academic Press, 1992. the back to test your understanding n Davie, Bruce S. Formal Specification of the articles and your ability to and Verification in VLSI Design. New 268 pp. $49.95. ISBN O-12-685245-6. extend the results. York: Columbia University Press, 1991. n Vassiliou, M. S., and Orenstein, J. Richards fails to say why he pro- 193 pp. $55.00. ISBN o-7486-0159-7. A. Computer Professional’s Quick Refer- ence. New York: McGraw-Hill, 1992. duced this book or for whom; indeed, n Garcia, Oscar N., and Chien, Yi- it seems to lack any audience. It will TZUU, eds. Knowledge-Based Systems: 266 pp. $34.95. ISBN o-07-067211-3 be rough going for readers without Fundamentals and Tools. Los Alami- (cloth). $24.95. ISBN 0-07-067212-l an extensive mathematical back- tos, Calif.: IEEE Computer Society (paper). ground and a broad knowledge of Press, 1992. 512 pp. $65.00 (paper). n Weinberg, Gerald M. Qualiv Soft- the fields covered. The book presents ISBN O-8186-1924-4. ware Management, Volume 1: Systems Richards’s natural computation Thinking. New York: Dorset House n Hart, Anna. Knowledge Acquisition approach, but this seems to be for Expert Systems. New York: Publishing, 1992. 318 pp. $40.00. merely a warmed-over version McGraw-Hill, 1992. 196 pp. $39.95. ISBN O-932633-22-6. of Marr’s approach, which is present- ISBN o-07-026911-4. .,...... ed much more readably and con- vincingly in Marr’s Vision (W. H. n Hirst, Graeme. Semantic Interpreta- Attention Authors! Freeman, 198.2). Natural Computation tion and the Resolution of Ambiguity. If you would like us to consider your is too scattered to serve as a reason- New York: Cambridge University book for review, have your publisher able survey of anything. Still, it Press, 1992. 263 pp. $22.95 (paper). send a copy to AI Magazine, 445 might be of use to readers wanting Burgess Drive, Menlo Park, CA Nigel Ward was a graduate student in easy access to seven or eight good computer science at the University of Cal- 94025. We’ll include it in the next papers in diverse fields who are also ifornia at Berkeley when he wrote this books received column. Receipt of a willing to ignore or sift through the review. He is now a post-doctoral student review copy, of course, doesn’t guar- chaff. at the University of Tokyo, RCAST. antee a review!

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