Introduction

Abstract

Vision is naively considered by many people as a process originating in an organism and directed toward the world. In early scientific illustrations rays were drawn from the eye to the object. Only in the last few centuries with the growing awareness of the nature of light has it become generally accepted that the relevant light travels from the object to the eye and that information flows from the world into the body. While this concept today is the uncontested basis of vision research, it tends to overemphasize the role of the viewing subject as that of a passive receiver. Particularly in comparative studies of small animals, stimulus—response chains are considered the hard core of visual behavior. Our experience as humans with vision as a continuous series of verifications or rejections of guesses is taken as a specialty of higher vertebrates.