[Optical illusions and the work of M.C. Escher]

The name Maurits Escher is inextricably linked with the notion of 'optical illusion', a type of illusion evoked by his 'impossible figures'. Despite the sober style in which he realised these figures, they go on to mesmerise generations of art lovers. It is unclear what causes this, and whether other factors than aesthetic ones are involved.
AIM: To gain insight into the genesis of optical illusions in Escher's work, and in the role of the perceptual system in that process.
METHOD: An explorative literature search in PubMed, Science.gov, Google Scholar, and the historical literature.
RESULTS: Since 'impossible figures' cannot be found in our natural environment, and therefore have a high novelty factor to the brain, they inevitably draw our attention. The reason that we remain captivated, is at least partly associated with the fact that the hippocampus and parahippocampal place area come into conflict with each other, and (in vain) accept the challenge to find a 'best fit'.
CONCLUSION: Fundamental research may benefit from Escher's 'impossible figures' to fathom the rules of our visual grammar. The optical illusions they evoke moreover constitute an ongoing source of inspiration for other artists, architects, and film makers.