28 September 2007
A study by researchers at UCL (University College London) explains why humans see illusions by showing that virtual robots trained to ‘see’ correctly also – as a consequence – make the same visual mistakes that we do. The study, published in the latest edition of PLoS Computational Biology, shows that illusions are an inevitable consequence of evolving useful behaviour in a complex world.
Dr. Beau Lotto, UCL Institute of Ophthalmology, said: “Sometimes the best way to understand how the visual brain works is to understand why sometimes it does not. Thus lightness illusions have been the focus of scientists, philosophers and artists interested in how the mind works for centuries. And yet why we see them is still unclear.”
To address the question of why humans see illusions, researchers at the UCL Institute of Ophthalmology used artificial neural networks, effectively virtual toy robots with miniature virtual brains, to model, not human vision as such, but human visual ecology. Dr David Corney in Dr. Lotto’s lab trained the virtual robots to predict the reflectance (shades of grey) of surfaces in different 3D scenes not unlike those found in nature. Although the robots could interpret most of the scenes effectively, and differentiate between surfaces correctly, they also – as a consequence – exhibited the same lightness illusions that humans see.