Dr Johannes M. Zanker Diplom (Tübingen, Germany), Ph.D. (Tübingen, Germany)  Professor of Neuroscience, HoD, Department of Psychology, Royal Holloway University of London, Egham, Surrey TW20 0EX Room W 214, Phone +44 (0)1784 443521, FAX +44 (0)1784 434347 email: j.zanker@rhul.ac.uk
Johannes joined the Vision Group (now BAB) in the Department of Psychology in March 2000. Trained as biologist with a special emphasis on theoretical aspects (cybernetics), his interest is now focused on visual information processing in humans, in particular motion perception, and possible applications in artificial systems. Previous appointments include:   Centre for Visual Sciences, RSBS, Australian National University, Canberra, Australia   Department of Psychology, University College London, England   Max-Planck-Institut für biologische Kybernetik, Tübingen, Germany In the Psychology Department Johannes has served as Director of Graduate Diploma, Director of Research, and Chair of the Departmental Ethics Committee, and in 2005 has been appointed as Head of Department. From 2003-2006 he was Scientific Director of HolViz Ltd. - a spinout company of RHUL to commercalise IP in visual processing. ... a few details about research, publications, current and previous teaching

summary of research interests:

Psychophysics and Computational Modelling

• Perception of primary and secondary motion.   Motion percepts are not only elicited by displacements of contours which are defined by changes in average luminance, but also by shifting contrast-defined or even motion-defined contours. This has interesting consequences for models of  motion processing. Together with Nick Burns (Adelaide, Australia) the interaction between primary and secondary motion was studied, leading to characterstic misperceptions of motion direction.
• Barbers Pole illusion.   The barberspole illusion (the diagonal stripes on a rotating cylinder seem to move vertically although the actually move horizontally) demonstrates how a particular shape of an aperture can change the perceived direction of motion (Fisher & Zanker 2001). Together with Eric Castet (Marseille, France) we investigated how the shape of a particular aperture forces the visual system to adopt a particular solution when integrating ambiguous motion signals from the central regions of the aperture and disambiguated motion signals from the boundary regions.
• Motion illusions perceived in static images.   The role of eye movements for perceiving motion in simple patterns such as used by Op artists, is investigated in collaboration with Robin Walker and Frouke Hermens. Small involuntary saccades, which are frequently made by observers under a wide range of conditions, lead to characteristically incoherent patterns of motion signals for Op art paintings like Bridget Riley's 'Fall' while generating coherent motion signals for control patterns, which then can be used to correct for retinal image shifts. Supported by The Leverhulme Trust.
• Understanding segmentation and motion transparency, optic flow.   In the psychophysical laboratory and in real life scenes, one may come across surprising situations in which two different directions of motion appear within the same patch of the visual field. This creates specific problems for the elementary motion detecting mechanism and can be interpreted in the context of motion-based contour detection and as limiting case of motion-based segmentation (in collaboration with Szonya Durant and Andrew Meso). The latest work in this area deals with the question of how attention affects the number of simultaneously perceived directions (in collaboration with Fatima Felisberti) and the cortical processing of transparent motion stimuli through fMRI (in collaboration with Andy Smith and Nathalie Williams). Supported by BBSRC and EPSRC.
• Visual ecology.   Vision is an exemplary case of  how sensory and, more general, nervous systems are adapted to the specific requirements which are imposed on an organism by its physical and social surroundings. The specific adaptations of  visual systems within their ecological niche and the information content of natural scenes, somehow reflected by the perceptual capabilities, are investigated in a collaboration with Jochen Zeil (CVS, Canberra, Australia) and Szonya Durant. In particular, we are interested in the strucutre of optical flow in natural environments and motion signal patterns in animal communication.
• Neuromorphic engineering.  The application of our knowledge about motion processing in biological visual systems, in particular motion parallax as depth cue, is pursued in a Royal Holloway spin-out company, HolViz Ltd., carrying out a proof-of-the-concept study for a novel design of 3D X-Ray security scanners.
• Speed perception.   The perceived speed of moving patterns depends on a number of  stimulus parameters other than physical speed, such as contrast or size. Together with Martin Egelhaaf (Bielefeld, Germany) and Srini Srinivasan (Canberra, Australia) I studied how velocity can be encoded in correlation-type motion detectors independent of spatial frequency. Effects of uncorrelated noise on speed perception are investigated in collaboration with Oliver Braddick (Oxford/UCL, England). The influence of apertures on perceived speed is investigated together with Josh Ryan (Canberra, Australia).
• Orientation maps in the human cortex.   From electrophysiological studies in primates it is apparent that in the retinotopic map of the visual field on the early cortex is organized in small modules called 'hypercolumns'. The preferred orientation of neurones in the primary visual cortex are arranged in a characteristic 'pinwheel' structure around centres with negligible orientation sensitivity. Can we trace these orientation maps in humans with psychophysical techniques ? (with Valentino Braitenberg, Tübingen, Germany).
• Perception of shape.   Gestalt psychology collected manifold evidence that the human visual system shows preferences for 'good shapes'. Can this notion be verified in a quantitative sense? In a collaboration with Tanja Quenzer (Tübingen, Germany) the discrimination of circles/squares from ovals/rectangles with different sidelengths was analysed under a variety of viewing conditions. Together with Manfred Fahle (Bremen, Germany) we also study shape deformations of moving contours. Recently this area of research was extended into the question of 3D shape, studying how shadows affect the perceived length in the Muller-Lyer and Judd illusion.
• Aesthetic choices and product design.   Preferences of human observers for simple shapes and compositions (object arrangements) are investigated by applying interactive methods (such as eye scanning patterns) in combination with evolutionary algorithms that are used as otimisation technique. Such methods are helpful as psychophysical method to explore multidimensional parameter spaces and can be used in product design applications to investigate consumer choice (together with Tim Holmes). Supported by EPSRC.

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a sample of recent publications

• Holmes, T and JM Zanker: Eye on the prize: Using Overt Visual Attention to Drive Fitness for Interactive Evolutionary Computation. in Proceedings of GECCO’08, 1531-1538 (2008)
• Meso, AI and JM Zanker: Separating global motion components in transparent visual stimuli – a phenomenological analysis. in Springer LNCS proceedings of ICANN (2008)
• Durant, S. and J.M. Zanker: Combining direction and speed for the localisation of visual motion defined contours. Vision Research 48 (8), 1053-1600 (2008)
• Zanker, J.M.: Animal Communication: Reading Lizard's Body Language in Context. Current Biology 17 (18), R806-R808 (2007)
• Felisberti, F. and J.M Zanker: Attention modulates perception of transparent motion. Vision Research 45 (19), 2587-2599 (2005)
• Zanker, J.M.: A computational analysis of separating motion signals in transparent random dot kinematograms. Spatial Vision 18 (4), 431-445 (2005)
• Zanker, J.M. and A.-al-J. Kane Abdullah: Are size illusions in simple line drawings affected by shading ? Perception 33, 1475 - 1482 (2004)
• Zanker, J.M. and R. Walker: A new look at Op art : towards a simple explanation of illusory motion. Naturwissenschaften , 75-94 (2004)
• Zanker, J.M.: Looking at Op Art from a Computational Viewpoint. Spatial Vision 17, 75-94 (2004)
• Zanker, J.M., M. Doyle and R. Walker: Gaze stability of observers watching Op Art pictures. Perception 32, 1037-1049 (2003)
• Zanker, J.M. and J.P. Harris: On temporal hyperacuity in the human visual system. Vision Research 42, 2499-2508 (2002)
• Zanker, J.M. and J. Zeil: An analysis of the motion signal distributions emerging from locomotion through a natural environment. In: Biologically Motivated Computer Vision 2002, Lecture Notes in Computer Science 2525, Eds. H.H. Bülthoff, S-W. Lee, T.A. Poggio and C.Wallraven, Springer-Verlag Berlin Heidelberg (2002), pp. 146-156.
• Zanker, J.M. and J. Zeil (eds): Motion Vision: Computational, Neural and Ecological Constraints. Springer Verlag, Berlin Heidelberg New York, (2001)
• Fisher, N. and J.M. Zanker: The Directional Tuning of the Barber Pole Illusion. Perception 30, 1321-1336 (2001)
• Zanker, J.M. and N.R. Burns: The interaction of first- and second-order direction in motion-defined motion. J. Opt. Soc. Am. A 18, 2321-2330 (2001)
• Pix, W., J. M. Zanker and J. Zeil: The optomotor response and spatial resolution in the visual system of male Xenos vesparum (Strepsitera). J. Exp. Biol. 203, 3397-3409 (2000)
• Patzwahl, D. R. and J. M. Zanker: Mechanisms of human motion perception: combining evidence from evoked potentials, behavioural performance, and computational modelling. European Journal of Neuroscience 12, 273-282 (2000)
• Castet, E. and J.M. Zanker: Long-range interactions in the spatial integration of motion signals. Spatial Vision 12, 287-308 (1999)
• Zanker, J.M., M. Srinivasan and M. Egelhaaf: Speed Tuning in Elementary Motion Detectors of the Correlation Type. Biol. Cybern. 80, 109-116 (1999)
• Zanker, J.M. and O. Braddick: How does noise influence the estimation of speed ? Vision Research 39, 2411-2420 (1999)
• Zeil, J. and J. M. Zanker: A glimpse into crabworld. Vision Research 37, 3417-3426 (1997)

and here is something about current teaching...

course co-ordinator for PS1061C  Sensation and Perception

•   course outline of PS1061 and coursework instructions -- NEW: course intranet forum for FAQ
•   lecture 1: Introduction: Perception as Gateway to the World
•   lecture 2: Visual Perception 1: Learning to Read the Neural Code
•   lecture 3: Visual Perception 2: Illusions as Key to Reality
•   lecture 4: Visual Perception 3: Travelling through space and time
•   lecture 5: Auditory Perception: From Noise to Sound
•   lecture 6: Touch, Taste and Smell: Basic but Hidden Senses?
•   lecture 10: Conceptual Frameworks: Making Sense of the World

supervision of Third Year Research Projects PS3200

• areas of project supervision in previous years, with some initial project ideas
• project suggestions for 2006/07: change blindness and illusions in real space

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and more about previous teaching...

course co-ordinator for third year option PS3060  Perception and Action

• lecture 1: introduction - basics of sensory-motor control
• lecture 2: look from the cockpit of a fly - the ecology of navigation
• lecture 3: driving a vehicle: controlling heading, avoid collision, braking
• lecture 4: cricket: how to hit a ball that can’t be seen
• lecture 5: bio-robotics &  neuro-engineering

course co-ordinator for PS1020C  Cognitive Psychology I until 2003 (old version)

course co-ordinator for PS2020A Cognitive Psychology II in 2000/2001 (old version)

teaching some second-year PS2080 Conceptual Issues in Psychology

• Neuroscience I: historical concepts
• Neuroscience II: current approaches

teaching some third-year PS3080 Philosophical Psychology

• index of Evolution lectures and study questions

• lecture on probability
• lecture on hypothesis testing
• lecture on non-parametric tests with sign-test appendix
• lecture on fundamentals of correlation
• lecture on correlation and regression
• statistics workshop: probability
• statistics experiment, practising t-tests : Muller-Lyer Illusion

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last update 06-Jan-2009