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Interplay of object knowledge and sampling strategies in the perception of object surface properties

Recent evidence from our laboratory at Giessen University indicates that humans can use relatively simple strategies when they explore the surface of a real 3D object while trying to recover its color. For instance, we tend to look at the brightest areas of an object in order to determine its lightness (Toscani, Valsecchi & Gegenfurtner, 2013a). Furthermore, our results indicate that the way we sample the surface of an object with eye fixations determines our final perceptual representation of its color. At the same time, our eye movements can also be guided relatively flexibly by the way we interpret and segment the scene we are looking at (Toscani, Valsecchi & Gegenfurtner, 2013b).
When dealing with familiar objects, however, the way we perceived their color is conditioned by our knowledge, so that, for instance, a banana will appear of a more saturated yellow than it really is, a phenomenon known as memory-color effect (Hansen et al., 2006; Olkkonen et al., 2008). 
In this project we will investigate how these two fundamentally different factors, low level sampling strategies and top-down color memory, interact in determining how familiar objects appear to us. In order to answer this question we will use eye tracking and psychophysical methods, using both real and rendered stimuli.

Hansen, T., Olkkonen, M., Walter, S. & Gegenfurtner, K.R. (2006) Memory modulates color appearance. Nature Neuroscience,  9, 1367-1368.

Olkkonen, M., Hansen, T. & Gegenfurtner, K.R. (2008) Colour appearance of familiar objects: effects of object shape, texture and illumination changes. Journal of Vision, 8(5):13, 1-16.

Toscani, M., Valsecchi, M. & Gegenfurtner, K.R. (2013a) Optimal sampling of visual information for lightness judgments. Proceedings of the National Academy of Sciences USA, 110(27), 11163-11168.

Toscani, M., Valsecchi, M. & Gegenfurtner, K.R. (2013b) Selection of visual information for lightness judgments by eye movements. Philosophical Transactions of the Royal Society B: Biological Sciences, in press.

Early Stage Researcher
Justus-Liebig-Universität Gießen
Project supervisors
Principal Investigator
Justus-Liebig-Universität Gießen