The week after getting back from Bombay was fully occupied with construction and painting. The work I am making is based on something called the Cornsweet illusion, which reveals how the brain determines what we see, not our eyes. It involves a field of uniform grey, bisected by a narrow strip in which a light edge meets a dark edge, both fading away into the grey background. The result s that we perceive the whole of the side with the dark edge being darker than the other half. It’s a variation or development of a phenomenon known as Mach’s Bands, described by the same Ernst Mach whose work on mass and gravitation provided the conceptual groundwork for Unni’s Cosmic Relativity.
I painted a small wall in the studio as a test, and realised that I could improve on the version that one normally sees, by reducing the tonal difference at the edge transition. The result is that one sees a white square next to a pale grey square, with absolutely no indication that almost the whole area is actually exactly the same tone. It’s not an illusion that flips between two alternative ways of perceiving it. The brain literally refuses to let you see the truth. It’s because the brain is always tenaciously trying to construct a 3D model of the space surrounding us, from 2D images on the retinas. As a result the effect is far more pronounced when it forms part of a space, as in this installation, than in a printed or screen image.
