Is there a neural common factor for visual illusions?

It has been reported that the surface area of the human primary visual cortex predicts the susceptibility to several spatial contextual illusions. Yet, contrary to common belief, illusions correlate only weakly at the perceptual level, raising the question of how they can correlate with a neural measure like V1 surface area. In addition, mounting evidence suggests that there is substantial interindividual variability not only in neural function and anatomy but also in the mapping between the two, which further challenges the findings of a neural common factor for illusions. In light of these concerns, our first goal was to re-evaluate the previous imaging results. Seeking to investigate whether these findings generalize, we expanded our study to other illusions. We could not replicate previous findings and did not find any other significant correlations, either at the perceptual level or between illusion susceptibility and visual functional neuroanatomy.