| Pouget, A., Deneve, S., Duhamel, J.-R. A computational perspective on the neural basis of multisensory spatial representation Nature reviews Neuroscience 2002 (3):741-474 [pdf] |
| We argue that current theories of multisensory representations are inconsistent with the existence of a large proportion of multimodal neurons with gain fields and partially shifting receptive fields. Moreover, these theories do not fully resolve the recoding and statistical issues involved in multisensory integration. An alternative theory, which we have recently developed and review here, has important implications for the idea of 'frame of reference' in neural spatial representations. This theory is based on a neural architecture that combines basis functions and attractor dynamics. Basis function units are used to solve the recoding problem, whereas attractor dynamics are used for optimal statistical inferences. This architecture accounts for gain fields and partially shifting receptive fields, which emerge naturally as a result of the network connectivity and dynamics. |
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| Romney, A.K., Indow, T. A model for the simultaneous analysis of reflectance spectra and basis factors of Munsell color samples under D65 illumination in three-dimensional Euclidean space Proceedings of the National Academy of Sciences USA 2002 (99)17:11543-11546 |
| In this paper we present the results of an analysis of the physically measured surface reflectance spectra of 360 matte Munsell chromatic color chips plus 10 flat achromatic vectors corresponding to Munsell value levels 10 (white) to 1 (near black) for a total sample size of 370. Each of the 370 spectra was multiplied by the spectral radiant power distribution of D65 light so that the final results represent the spectra of reflected light from Munsell color chips under D65 illumination. We simultaneously model the structure of the color chips and the spectra in a common three-dimensional Euclidean space, oriented to yield the most interpretable structure with respect of the Munsell color structure. In this orientation, axis 1 roughly corresponds to the mean power of the spectral reflectance (approximate Munsell value), axis 2 goes from Munsell red to blue-green, and axis 3 goes from Munsell green-yellow to purple. Basis factors for the spectra are also plotted against wavelength and Munsell hue. These plots have implications for theories of opponent processes. By plotting the chips and spectra in the same space we obtain virtually exact correspondences between the various Munsell hues and spectral values in nanometers for comparison to those obtained by previous researchers. Mathematical derivations are provided to validate the common Euclidean model. |
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| Lotto, B.R., Purves, D. A rationale for the structure of color space Trends in Neuroscience 2002 (25)2:84-88 [html] |
| The colors perceived by humans in response to light stimuli are generally described in terms of four color categories (reds, greens, blues and yellows), the members of which are systematically arrayed around gray. This broadly accepted description of color sensation differs fundamentally from the light that induces it, which is neither 'circular' nor categorical. What, then, accounts for these discrepancies between the structure of color experience and the physical reality that underlies it? We suggest that these differences are based on two related requirements for successful color vision: (1) that spectra be ordered according to their physical similarities and differences; and (2) that this ordering be constrained by the four-color map problem. |
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| Lee, J.A., Lendasse, A., Donckers, N., Verleysen, M. A robust nonlinear projection method 2000 :13-20 [html] |
| This paper describes a new nonlinear projection method. The aim is to design a user-friendly method, tentativ ely as easy to use as the linear PCA (Principal Component Analysis). The method is based on CCA (Curvilinear Component Analysis). This paper presen ts tw o improvements with respect to the original CCA: a better beha vior in the projection of highly nonlinear databases (like spirals) and a complete automation in the choice of the parameters value. |
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| Yang, Z., Purves, D. A statistical explanation of visual space Nature Neuroscience 2003 (6)6:632-640 |
| The subjective visual space perceived by humans does not reflect a simple transformation of objective physical space; rather, perceived space has an idiosyncratic relationship with the real world. To date, there is no consensus about either the genesis of perceived visual space or the implications of its peculiar characteristics for visually guided behavior. Here we used laser range scanning to measure the actual distances from the image plane of all unoccluded points in a series of natural scenes. We then asked whether the differences between real and apparent distances could be explained by the statistical relationship of scene geometry and the observer. We were able to predict perceived distances in a variety of circumstances from the probability distribution of physical distances. This finding lends support to the idea that the characteristics of human visual space are determined probabilistically. |
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| Ziv, E., Middendorf, M., Wiggins, C. An information-theoretic approach to network modularity Econophysics Forum 2004 [html] |
| Exploiting recent developments in information theory, we propose, illustrate, and validate a principled information-theoretic algorithm for module discovery and resulting measure of network modularity. This measure is an order parameter (a dimensionless number between 0 and 1). Comparison is made to other approaches to module-discovery and to quantifying network modularity using Monte Carlo generated Erdos-like modular networks. Finally, the Network Information Bottleneck (NIB) algorithm is applied to a number of real world networks, including the "social" network of coauthors at the APS March Meeting 2004. |
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| Sid-Ahmed, B., Laurent, A., Gros, P. Approximate k-Nearest-Neighbor Searches: A New Algorithm with Probabilistic Control of the Precision 2002 [html] |
| This paper describes a new approach for performing efficient approximate k-nearest-neighbor searches in high-dimensional databases. This approach allows a fine and intuitive control over the precision of the search by setting at run time the maximum probability for a vector that would be in the exact answer set to be missing in the approximate set of answers. One of the contribution of this paper is an off-line process computing controlled approximations shrinking each cluster within which feature vectors are enclosed. Those approximations are values for (approximate) radiuses of clusters, and they are computed for all the levels of precision defined beforehand. Therefore, to answer a query, the search process simply considers the appropriate approximations corresponding to the desired level of precision- . This may cause the actual nearest-neighbors of the query point to be ignored. Our method, however, probabilistically bounds the chances for this to happen. This paper also presents a performance study of the implementa- tion. It shows, for example, that our method is 6.72 times faster than the sequential scan when it handles more then 5 10^6 24-dimensions vectors, even when the probability of missing one of the true nearest-neighbors is below 0.01. |
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| Indyk, P., Motwani, R. Approximate nearest neighbors, toward removing the curse of dimensionality 1998 :604-613 [html] |
| We present two algorithmic results for the approximate nearest neighbors that significantly improve two known bounds: preprocessing cost polynomial in n and d, query time polynomial in log n and d. |
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| Davies, I., Franklin, A. Categorical similarity may affect colour pop-out in infants after-all British Journal of Developmental Psychology 2002 (20):185-203 [pdf] |
| Gerhardstein, Renner, and Rovee-Collier (1999) reported an investigation of pop-out in infant visual search with targets differing in colour from the distractors. They varied the perceptual distance between target and distractors and their categorical relationship. Targets were either in the same category as distractors or in a different category. They reported that at 3 months, infants showed increased pop-out as perceptual distance increased, but there was no categorical effect. Here, we argue that their stimuli were not adequate to address these issues. Use of incandescent light rather than the normal illuminant C differentially affected the perceptual differences among their stimuli, and there may have been an unintended category boundary present in an intended within category pair. We argue that these faults in the stimuli can account for their pattern of results. They were aware of the possible consequences of using incandescent light and ran a preliminary study on adults comparing category membership and perceived similarity among their stimuli under incandescent light and illuminant C. They report that the illuminant had no effect. We replicated and extended their adult study and found that there were effects of the illuminant as well as evidence consistent with the unintended boundary. Reasons for the discrepant results are discussed, and the requirements for a valid investigation outlined. |
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| Jakab, Z. Color Experience: Empirical Evidence Against Representational Externalism 2001 [pdf] |
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| Lungarella, M., Metta, G., Pfeifer, R., Sandini, G. Developmental robotics: a survey Connection Science 2004 (0)0:1-40 [pdf] |
| Developmental robotics is an emerging field located at the intersection of robotics, cognitive science and developmental sciences. This paper elucidates the main reasons and key motivations behind the convergence of fields with seemingly disparate interests, and shows why developmental robotics might prove to be beneficial for all fields involved. The methodology advocated is synthetic and two-pronged: on the one hand, it employs robots to instantiate models originating from developmental sciences; on the other hand, it aims to develop better robotic systems by exploiting insights gained from studies on ontogenetic development. This paper gives a survey of the relevant research issues and points to some future research directions. |
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| Weng, J., Zhang, Y. Developmental robots: A new paradigm 2002 [pdf] |
| It has been proved to be extremely challenging for humans to program a robot to such a su±cient degree that it acts properly in a typical unknown human environment. This is especially true for a humanoid robot due to the very large number of redundant degrees of freedom and a large number of sensors that are required for a humanoid to work safely and e®ectively in the human environment. How can we address this fundamental problem? Motivated by human mental development from infancy to adulthood, we present a theory, an architecture, and some experimental results showing how to enable a robot to develop its mind automatically, through online, real time interactions with its environment. Humans mentally raise the robot through robot sitting and robot schools instead of task-specific robot programming. |
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| Sugita, Y. Experience in early infancy is indispensable for color perception Current Biology 2004 (14):1267-1271 [html] |
| Early visual experience is indispensable to shape the maturation of cortical circuits during development. Monocular deprivation in infancy, for instance, leads to an irreversible reduction of visually driven activity in the visual cortex through the deprived eye and a loss of binocular depth perception. It was tested whether or not early experience is also necessary for color perception. Infant monkeys were reared for nearly a year in a separate room where the illumination came from only monochromatic lights. After extensive training, they were able to perform color matching. But, their judgment of color similarity was quite different from that of normal animals. Furthermore, they had severe deficits in color constancy; their color vision was very much wavelength dominated, so they could not compensate for the changes in wavelength composition. These results indicate that early visual experience is also indispensable for normal color perception. |
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| Franz, M.O., Chahl, J.S., Krapp, H.G. Insect-inspired estimation of egomotion Neural Computation 2004 (6)11: [pdf] |
| Tangential neurons in the fly brain are sensitive to the typical optic flow patterns generated during egomotion. In this study, we examine whether a simplified linear model based on the organization principles in tangential neurons can be used to estimate egomotion from the optic flow. We present a theory for the construction of an estimator consisting of a linear combination of optic flow vectors that incorporates prior knowledge about the distance distribution of the environment and about the noise and egomotion statistics of the sensor. The estimator is tested on a gantry carrying an omnidirectional vision sensor. The experiments show that the proposed approach leads to accurate and robust estimates of rotation rates, whereas translation estimates are of reasonable quality, albeit less reliable. |
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| Guigon, E. Interpolation and extrapolation in human behavior. Journal of Cognitive Neuroscience 2004 (16)3 [pdf] |
| Unlike most artificial systems, the brain is able to face situations that it has not learned or even encountered before. This ability is not in general echoed by the properties of most neural networks. Here, we show that neural computation based on least-square error learning between populations of intensitycoded neurons can explain interpolation and extrapolation capacities of the nervous system in sensorimotor and cognitive tasks. We present simulations for function learning experiments, auditory visual behavior, and visuomotor transformations. The results suggest that induction in human behavior, be it sensorimotor or cognitive, could arise from a common neural associative mechanism. |
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| Jack, A.I., Shallice, T. Introspective physicalism as an approach to the science of consciousness. Cognition 2001 (79)1-2:161-196 [pdf] |
| Most theories of consciousness are based on vague speculations about the properties of conscious experience. We aim to provide a more solid basis for a science of consciousness. We argue that a theory of consciousness should provide an account of the very processes that allow us to acquire and use information about our own mental states the processes underlying introspection. This can be achieved through the construction of information processing models that can account for Type-C processes. Type-C processes can be specified experimentally by identifying paradigms in which awareness of the stimulus is necessary for an intentional action. The Shallice (1988b) framework is put forward as providing an initial account of Type-C processes, which can relate perceptual consciousness to consciously performed actions. Further, we suggest that this framework may be refined through the investigation of the functions of prefrontal cortex. The formulation of our approach requires us to consider fundamental conceptual and methodological issues associated with consciousness. The most significant of these issues concerns the scientific use of introspective evidence. We outline and justify a conservative methodological approach to the use of introspective evidence, with attention to the difficulties historically associated with its use in psychology. |
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| Pierce, D., Kuipers, B. Map learning with Uninterpreted Sensors and Effectors Artificial Intelligence 1997 (92):169-229 |
| This paper presents a set of methods by which a learning agent can learn a sequence of increasingly abstract and powerful interfaces to control a robot whose sensorimotor apparatus and environment are initially unknown. The result of the learning is a rich hierarchical model of the robot's world (its sensimotor apparatus and environment). The learning methods rely on generic properties of the robot's world such as almost-everywhere smooth effects of motor control signals on sensory features. At the lowest level of the hierarchy, the learning agent analyzes the effects of its motor control signals in order to define a new set of control signals, one of each of the robot's degrees of freedom. It uses a generate-and-test approach to define sensory features that capture important aspects of the environment. It uses linear regression to learn models that characterize context-dependent effects of the control laws for finding and following paths defined using constraints on the learned features. The agent abstracts these control laws, which interact with the continuous environment, to a finite set of actions that implement discrete state transitions. At this point, the agent has abstracted the robot's continuous world to a finite-state world and can use existing methods to learn its structure. The learning agent's methods are evaluated on several simulated robots with different sensorimotor systems and environments. |
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| Normal and defective colour vision 2003 |
| Courte réflexions sur les notions de Contant L-cone Excitation Plane, et Contant Rod Excitation solid. |
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| Teller, D.Y. Spatial and temporal aspects of infant color vision Vision Research 1998 (38):3275-3282 [html] |
| The present paper constitutes a review of the literature on young infants' chromatic discrimination capabilities. A series of early studies showed that infants as young as two months postnatal can make at least some chromatic discriminations between stationary, homogeneous fields of different wavelength compositions. Current studies of spatial and temporal contrast sensitivity functions (CSFs) for red/green isoluminant stimuli suggest that spatial chromatic CSFs show developmental changes in sensitivity and spatial scale, but not curve shape; while temporal chromatic CSFs (tCSFs) show developmental changes in sensitivity and curve shape, but not temporal scale. Infants can also code the direction of motion of moving isoluminant red/green gratings, for both continuous and quadrature motion. The possible mechanisms that underlie infants' chromatic discriminations are discussed. |
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| DiCarlo, J.M., Wandell, B.A. Spectral estimation theory: beyond linear but before Bayesian Journal of the Optical Society of America A 2003 (20)7:1261-1270 [pdf] |
| Most color-acquisition devices capture spectral signals by acquiring only three samples, critically undersampling the spectral information. We analyze the problem of estimating high-dimensional spectral signals from low-dimensional device responses. We begin with the theory and geometry of linear estimation methods. These methods use linear models to characterize the likely input signals and reduce the number of estimation parameters. Next, we introduce two submanifold estimation methods. These methods are based on the observation that for many data sets the deviation between the signal and the linear estimate is systematic; the methods incorporate knowledge of these systematic deviations to improve upon linear estimation methods. We describe the geometric intuition of these methods and evaluate the submanifold method on hyperspectral image data. |
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| Pellionisz, A., Llinas, R. Tensor network theory of the metaorganization of functional geometries in the central nervous system Neuroscience 1985 (16)2:245-273 [html] |
| Here we present an elaboration and a quantitative example for a hypothetical neuronal process, implementing what we refer to as the metaorganization principle. This process allows the internalization of external (body) geometries into the central nervous system (CNS) and a reciprocal and equally important action of the CNS geometry on the external (body) geometry. The hypothesis is based on the destination, within the CNS, between covariant sensory and contravariant motor vectorial expressions of the extrinsic geometry. These sensory and motor expressions, given in natural co-ordinate systems, are transformed from one to the other by a neuronal network, which acts as a metric tensor. The metric tensor determines the relationship of these two expressions and thus comprises the functional geometry of the system. The emergence through metaorganization of networks that implement such metric function is viewed as the result of interactions between the covariant motor execution which generates a physical action on the external world (via the musculoskeletal system) and the covariant sensory proprioception which measures the effect of such motor output. In this transformation of contravariants to covariants by the physical geometry of the motor system, a covariant metric tensor is expressed implicitly. However, co-ordinated motor action requires its dual tensor (the contravariant metric), which is assembled in the CNS based on the metaorganization principle, i.e. the ability of CNS and external geometries to mold one another. The two metric transformations acting on each other detect error signals whenever the match of the physical and functional geometries is imperfect. Such error signals are utilized by the metaorganization process to improve the match between the two metrics, so that with use the internal representation becomes increasingly homeometric with the geometry of the external world. |
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| Burgund, E.D., Marsolek, C.J. Viewpoint-invariant and viewpoint-dependent object recognition in dissociable neural subsystems Psychonomics Bulletin & Review 2000 (7)3:480-489 [pdf] |
| Participants viewed objects in the central visual field and then named either same or different depthorientation views of these objects presented briefly in the left or the right visual field. The differentorientation views contained either the same or a different set of parts and relations. Viewpoint-dependent priming was observed when test views were presented directly to the right hemisphere (RH), but not when test views were presented directly to the left hemisphere (LH). Moreover, this pattern of results did not depend on whether the same or a different set of parts and relations could be recovered from the different-orientation views. Results support the theory that a specific subsystem operates more effectively than an abstract subsystem in the RH and stores objects in a manner that produces viewpointdependent effects, whereas an abstract subsystem operates more effectively than a specific subsystem in the LH and does not store objects in a viewpoint-dependent manner. |
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| Feldman, J. What is a visual object ? Trends in Cognitive Sciences 2003 (7)6:252-256 [pdf] |
| The concept of an object plays a central role in cognitive science, particularly in vision, reasoning and conceptual development but it has rarely been given a concrete formal definition. Here I argue that visual objects cannot be defined according to simple physical properties but can instead be understood in terms of the hierarchical organization of visual scene interpretations. Within the tree describing such a hierarchical description, certain nodes make natural candidates as the joints between objects, representing division points between parts of the image that cohere internally but do not perceptually group with one another. Thus each subtree hanging from such a node corresponds to a single perceived object . This formal defi- nition accords with several intuitions about the way objects behave. |
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| Pouget, A., Deneve, S., Duhamel, J.-R. A computational perspective on the neural basis of multisensory spatial representation Nature reviews Neuroscience 2002 (3):741-474 |
| Romney, A.K., Indow, T. A model for the simultaneous analysis of reflectance spectra and basis factors of Munsell color samples under D65 illumination in three-dimensional Euclidean space Proceedings of the National Academy of Sciences USA 2002 (99)17:11543-11546 |
| Lotto, B.R., Purves, D. A rationale for the structure of color space Trends in Neuroscience 2002 (25)2:84-88 |
| Lee, J.A., Lendasse, A., Donckers, N., Verleysen, M. A robust nonlinear projection method 2000 :13-20 |
| Yang, Z., Purves, D. A statistical explanation of visual space Nature Neuroscience 2003 (6)6:632-640 |
| Philipona, D., O'Regan, J.K. AS Suppleance Arobase 2004 |
| Nolfi, S., Marocco, D. Active Perception: A Sensorimotor Account of Object Categorization From Animals to Animats 7 2002 |
| Philipona, D., O'Regan, J.K. Agir dans l'espace 2004 |
| Ziv, E., Middendorf, M., Wiggins, C. An information-theoretic approach to network modularity Econophysics Forum 2004 |
| Sid-Ahmed, B., Laurent, A., Gros, P. Approximate k-Nearest-Neighbor Searches: A New Algorithm with Probabilistic Control of the Precision 2002 |
| Indyk, P., Motwani, R. Approximate nearest neighbors, toward removing the curse of dimensionality 1998 :604-613 |
| Davies, I., Franklin, A. Categorical similarity may affect colour pop-out in infants after-all British Journal of Developmental Psychology 2002 (20):185-203 |
| Jakab, Z. Color Experience: Empirical Evidence Against Representational Externalism 2001 |
| Rosenstein, M.T., Cohen, P.R. Continuous Categories for a mobile robot 1999 |
| Blackmore, S. Crossing the chasm of consciousness Trends in Cognitive Sciences 2002 (6)7 |
| Lungarella, M., Metta, G., Pfeifer, R., Sandini, G. Developmental robotics: a survey Connection Science 2004 (0)0:1-40 |
| Weng, J., Zhang, Y. Developmental robots: A new paradigm 2002 |
| Weng, J. Developmental robots: theory and experiments International Journal of Humanoid Robotics 2003 |
| Sugita, Y. Experience in early infancy is indispensable for color perception Current Biology 2004 (14):1267-1271 |
| Ashtekar, A., Corichi, A., Pierri, M. Geometry in Color Perception ESI 1997 |
| Crutchfield, J.P. Information and its metric Nonlinear Structures in Physical Systems - Pattern formation and Chaos and Waves 1990 :119-130 |
| Franz, M.O., Chahl, J.S., Krapp, H.G. Insect-inspired estimation of egomotion Neural Computation 2004 (6)11: |
| Guigon, E. Interpolation and extrapolation in human behavior. Journal of Cognitive Neuroscience 2004 (16)3 |
| Jack, A.I., Shallice, T. Introspective physicalism as an approach to the science of consciousness. Cognition 2001 (79)1-2:161-196 |
| Chaperon, M. Jets, transversalité, singularités: petite introduction aux grandes idées de René Thom actes du colloque international Géométrie au vingtième siècle 2001 |
| Pierce, D., Kuipers, B. Map learning with Uninterpreted Sensors and Effectors Artificial Intelligence 1997 (92):169-229 |
| Klute, G.K., Czerniecki, J.M., Hannafor, B. McKibben Artificial Muscles: Pneumatic Actuators with Biomechanical Intelligence IEEE/ASME 1999 International Conference on Advanced Intelligent Mechatronics (AIM'99) 1999 |
| Vollgraf, R., Obermayer, K. Multi Dimensional ICA to Separate Correlated Sources 2001 |
| Lenz, R., Meer, P. Non-Euclidean structure of spectral color space 1998 |
| Normal and defective colour vision 2003 |
| Vieville, T., Faugeras, O.D. Perception Visuelle en Robotique: Profiter de la Biologie pour faire des Systèmes Adaptatifs 2001 |
| Brainard, D.H., Maloney, L.T. Perception of color and material properties in complex scenes Journal of Vision 2004 (4):ii-iii |
| Gonzalez, J., Bach-y-Rita, P. Perceptual adaptive recalibration: tactile sensory substitution in blind subjects Behavior and Philosophy 2003 (): |
| Philipona, D., O'Regan, J.K. Philosophie de la nature aujourd'hui? 2004 |
| Metta, G., Sandini, G., Natale, L., Panerai, F. Sensorimotor interaction in a developing robot 2001 |
| Teller, D.Y. Spatial and temporal aspects of infant color vision Vision Research 1998 (38):3275-3282 |
| DiCarlo, J.M., Wandell, B.A. Spectral estimation theory: beyond linear but before Bayesian Journal of the Optical Society of America A 2003 (20)7:1261-1270 |
| Pellionisz, A., Llinas, R. Tensor network theory of the metaorganization of functional geometries in the central nervous system Neuroscience 1985 (16)2:245-273 |
| Brassard, L. The Perception of the Image World 1998 |
| Pasquinelli, E. The awareness of perceptual illusions. Problems of coherence and dynamic knowledge. Philosophical Psychology 2004 |
| Gorea, A. Thoughts on the specific nerve energy Representation of vision. Trends and tacit assuptions in vision research. 1991 |
| Burgund, E.D., Marsolek, C.J. Viewpoint-invariant and viewpoint-dependent object recognition in dissociable neural subsystems Psychonomics Bulletin & Review 2000 (7)3:480-489 |
| Feldman, J. What is a visual object ? Trends in Cognitive Sciences 2003 (7)6:252-256 |