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. Author manuscript; available in PMC: 2009 Nov 11.
Published in final edited form as: Curr Biol. 2008 Nov 11;18(21):1707–1712. doi: 10.1016/j.cub.2008.09.025

Figure 2.

Figure 2

Sphere versus Ring. (A) A greater distribution of activity in V1 to the perceptually larger back sphere could result from either a positional shift in the cortical representation of the edges of the sphere (top) or an increase in the neural activity to the back sphere in combination with a saturating nonlinearity in the fMRI response (bottom). Note that the idealized activity responses are assuming that fixation is maintained at the center of the sphere. (B) These two alternative explanations can be distinguished by using a ring presented at close and far apparent depths while subjects fixate the center of the ring. Specifically, in the current experiment using rings, we will look for a shift in the location of the maximum response rather than a shift in the distribution.