Evidence from Geometry

Abstract

Dealing successfully with objects and conditions in the world entails another basic visual category: the geometry of objects. This domain is also rich in perceptual phenomenology that needs to be explained. The problem in understanding perceived geometry is much the same as the problem of understanding lightness values and colors: biological vision lacks the tools—in this case rulers, protractors, radar guns, laser range scanners—needed to measure geometrical reality. As a result, the geometries we see always differ from the measured parameters of the physical world. The aim of this chapter is to consider geometrical examples that further support the conclusion that vision operates by ranking perceptual values according to the frequency of occurrence of biologically useful stimulus patterns.