Illusions and Environment

The question of why we sometimes do not perceive the physical world as it really is, but can be tricked by visual or optical illusions, has long occupied science and society. But illusions aren’t a fault of our brains; they indicate certain functions in our visual perception. Accordingly, when researching the mechanisms of perceptual processing, optical illusions are particularly helpful.

Studies have shown that people from different cultures—for example, from Asia, Africa, or the West—display different susceptibility to illusions. We want to determine whether the physical environment also has an influence on how illusions are experienced. If so, this could indicate a change in visual perception in cities compared to the countryside. To answer this question, we analyze the environment in which people live—looking, for example, at how many trees and parks there are in the surrounding neighborhood, or how tall the buildings are—and at the same time investigate how residents perceive visual stimuli, using optical illusions such as the Ebbinghaus, Müller-Lyer, and Ponzo illusion.

In order to better analyze the direct influence of the current living environment, we use a twin design, running studies with monozygotic and dizygotic twin pairs, who are either genetically identical or similar. This allows us to specifically uncover how genes, early environmental factors, and the current environment influence visual perception.