Event Abstract

The yellow of a gray banana - Decoding colors from fMRI signals in the absence of chromatic stimulation

  • 1 Centre for Integrative Neuroscience, University of Tübingen, Germany
  • 2 Bernstein Center for Computational Neuroscience Tübingen, Germany

Some objects that we deal with on a daily basis are associated with an object-specific color – such as yellow for bananas, red for strawberries, green for lettuce, etc. Such objects are referred to as color-diagnostic and their associated color as their memory color (Hering, 1920). Psychophysical evidence shows that achromatic , i.e. grayscale, images of color-diagnostic objects elicit percepts that are differentially biased towards their memory color (Hansen et al., 2006; Olkkonen et al., 2008). This phenomenon suggests some form of learned and automatic association between colors and particular objects.

In the present study we tested whether neural responses to color-diagnostic objects convey color-specific information, even when the objects were presented achromatically to subjects who were naïve to the purpose of the study.

We first collected fMRI data while participants viewed grayscale images of 8 different color-diagnostic objects (4 colors, 2 per color). We then recorded responses to chromatic stimulation with red, green, blue, and yellow abstract color stimuli that contained no object information. All object and color stimuli were set to equiluminance for each subject individually. To analyze the data, we applied a whole-brain searchlight procedure by training linear support vector machine classifiers to distinguish between local voxel patterns associated with the four colors. They were then tested on patterns elicited by color-diagnostic achromatic objects to predict their correct memory colors.

At the group level, we found significant decoding accuracy in a large cluster covering foveal regions of early visual cortex. In some but not all individual subjects, smaller clusters were also evident in the fusiform gyrus.

Our results suggest that memory color and color signals evoked by chromatic stimulation share a common neural mechanism in early visual cortex. Retinotopic mapping in combination with classification techniques will be used to clarify the contribution of individual visual areas to this mechanism.

Acknowledgements

This work is supported by the Bundesministerium für Bildung und Forschung (BMBF - grant number FKZ 01GQ1002)

References

Hansen, T., Olkkonen, M., Walter, S., & Gegenfurtner, K. R. (2006). Memory modulates color appearance. Nat. Neurosci., 9(11).
Hering, E. (1920). Grundzüge der Lehre vom Lichtsinn. Berlin: Springer.
Olkkonen, M., Hansen, T., & Gegenfurtner, K. R. (2008). Color appearance of familiar objects: Effects of object shape, texture, and illumination changes. J. Vis., 8(5).

Keywords: Color Vision, human fMRI, Object knowledge

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

Presentation Type: Poster

Topic: Sensory processing and perception

Citation: Bannert MM and Bartels A (2012). The yellow of a gray banana - Decoding colors from fMRI signals in the absence of chromatic stimulation. Front. Comput. Neurosci. Conference Abstract: Bernstein Conference 2012. doi: 10.3389/conf.fncom.2012.55.00049

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

* Correspondence: Mr. Michael M Bannert, Centre for Integrative Neuroscience, University of Tübingen, Tübingen, 72076, Germany, mbannert@tuebingen.mpg.de

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