The Illusion of the Given and Its Role in Vision Research

Illusions in vision and other modalities are captivating displays of the virtual nature of our subjective world. For this reason, illusions have been an important subject of scientific and artistic endeavors. In his target article, Heiko Hecht discusses the utility of the illusion concept and arrives at the negative conclusion that the traditional understanding of illusions as a discrepancy between world and perception is misguided. In his opinion, the more interesting and revealing cases are when the discrepancy is noticed and accompanies the perceptual state, or when, in the cognitive domain, the discrepancies become exceedingly large, but go unnoticed nonetheless. In this commentary, I argue that Hecht’s criticism of the illusion concept is interesting and deserves further study. But at the current stage, I don’t see that the model captures the essential features of illusory states. The processes on which Hecht focuses can be considered metacognitive appraisals of the respective sensory events, an interesting topic by itself. In the second part and as an overview, I review how research on the classical apparent-motion illusion has shaped our understanding of the neural underpinnings of motion perception and consciousness in general.