Event Abstract

How Sensitive Is the Human Visual System to the Local Statistics of Natural Images?

  • 1 University of Tuebingen, Bernstein Center for Computational Neuroscience, Germany
  • 2 Max Planck Institute for Biological Cybernetics, Germany
  • 3 Eberhard Karls Universität Tübingen, AG Neuronale Informationsverarbeitung, Mathematisch-Naturwissenschaftliche Fakultät und Bernstein Center für Computational Neuroscience Tübingen, Germany
  • 4 Max-Planck-Institut für Intelligente Systeme, Abteilung Empirische Inferenz, Germany

A key hypothesis in sensory system neuroscience is that sensory representations are adapted to the statistical regularities in sensory signals and thereby incorporate knowledge about the outside world. Supporting this hypothesis, several probabilistic models of local natural image regularities have been proposed that reproduce neural response properties. Although many such physiological links have been made, these models have not been linked directly to visual sensitivity. Previous psychophysical studies focus on global perception of large images, so little is known about sensitivity to local regularities. We present a new paradigm for controlled psychophysical studies of local natural image regularities and use it to compare how well such models capture perceptually relevant image content. To produce image stimuli with precise statistics, we start with a set of patches cut from natural images and alter their content to generate a matched set of patches whose statistics are equally likely under a model’s assumptions. Observers have the task of discriminating natural patches from model patches in a forced choice experiment. The results show that human observers are remarkably sensitive to local correlations in natural images and that no current model is perfect for patches as small as 5 by 5 pixels or larger. Furthermore, discrimination performance was accurately predicted by model likelihood, an information theoretic measure of model efficacy, which altogether suggests that the visual system possesses a surprisingly large knowledge of natural image higher-order correlations, much more so than current image models. We also perform three cue identification experiments where we measure visual sensitivity to selected natural image features. The results reveal several prominent features of local natural image regularities including contrast fluctuations and shape statistics.

Acknowledgements

This work was supported by the Max Planck Society and the German Ministry of Education, Science, Research and Technology through the Bernstein award to MB (BMBF; FKZ: 01GQ0601) and in part through the Bernstein Computational Neuroscience Program Tuebingen (BMBF; FKZ: 01GQ1002).

Keywords: efficient coding, human vision, natural image statistics, sensory input statistics, Spatial Vision, texture perception

Conference: Bernstein Conference 2012, Munich, Germany, 12 Sep - 14 Sep, 2012.

Presentation Type: Poster

Topic: Sensory processing and perception

Citation: Gerhard H, Wichmann FA and Bethge M (2012). How Sensitive Is the Human Visual System to the Local Statistics of Natural Images?. Front. Comput. Neurosci. Conference Abstract: Bernstein Conference 2012. doi: 10.3389/conf.fncom.2012.55.00053

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Received: 25 May 2012; Published Online: 12 Sep 2012.

* Correspondence: Dr. Holly Eve Gerhard, University of Tuebingen, Bernstein Center for Computational Neuroscience, Tuebingen, Germany, holly.gerhard@bethgelab.org