Die Bestimmung der Beziehung zwischen subjektiver Empfindung und Diskriminationsvermögen durch eine Kombination aus Psychophysik, Computationaler Modellierung und der Messung neuronaler Antworten

• Applicant: Professorin Dr. Marianne Maertens
• Subject Area: General, Cognitive and Mathematical Psychology
• Term: from 2011 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 188583648

• Final Report Year: 2016

Final Report Abstract

Making Sense of Light: Perceiving Surface Lightness from Retinal Luminance. The aphorism seeing is believing expresses the common notion that physical visual evidence is deemed particularly convincing. Seeing feels easy and because one can do it with so little effort it must be easy. This is not the case. The complexity of the visual machinery is enormous, but it is well hidden from its user. The goal of this project was to get a better understanding of the mechanisms that allow humans to perceive object properties such as surface lightness from the ambiguous retinal input signal. This project extends our understanding of lightness perception with these contributions: 1. We developed a stimulus of intermediate complexity to study lightness perception under more realistic conditions. 2. Using more realistic stimuli we show that stimulus appearance and discriminability rely on the same mechanism. 3. We provide evidence that two lightness phenomena, simultaneous contrast and assimilation, rely on the same mechanism. 4. We show that the widely held belief that increments are never matched with decrements is no longer valid. In particular when surfaces are presented in different illuminations observers perceive surfaces of opposing contrast as perceptually equal. 5. We show that an entire class of bottom-up computational models of lightness perception, namely spatial filtering models, is inadequate to capture the early mechanisms of visual processing of lightness perception. 6. We proposed a normalized contrast model and show that among the most popular models of lightness models our model accounted best for the observed data.

Publications

• (2013). Relating appearance to neural activity: linking assumptions for studying the perception of lightness in naturalistic contexts. Visual Neuroscience, 24, 1-10
  Maertens, M. and Shapley, R.
  
• (2013). When luminance increment thresholds depend on apparent lightness. Journal of Vision, 13
  Maertens, M. and Wichmann, F.A.
  
• (2014). Linking luminance and lightness by global contrast normalization. Journal of Vision, 14
  Zeiner, K. and Maertens, M.
  
• (2015). Context affects lightness at the level of surfaces, Journal of Vision, 15(1)
  Maertens, M., Wichmann, F.A. and Shapley, R.
  
• (2015). Exploitation of environmental constraints in human and robotic grasping. The International Journal of Robotics Research, 34(7), 1021–1038
  Eppner, C., Deimel, R., Alvarez-Ruiz, J., Maertens, M., and Brock, O.
  
• (2015). Noise masking of White’s illusion exposes the weakness of current spatial filtering models of lightness perception. Journal of Vision, 15(14), 1-17
  Betz, T., Wichmann, F.A., Shapley, R. and Maertens, M.
  
• (2015). Testing the role of luminance edges in White’s illusion with contour adaptation. Journal of Vision, 15(11), 1-16
  Betz, T., Wichmann, F.A., Shapley, R. and Maertens, M.
  
• Measuring the Visual Salience of 3D Printed Objects. IEEE Computer Graphics and Applications, Vol 36 Issue 4 , July-Aug. 2016, 46-55
  Wang, X., Lindlbauer, D., Lessig, C., Maertens, M. and Alexa, M.