ABSTRACT
Throughout this book we have emphasised the applied, functional character of vision. Vision exists in humans and other animals because it is an aid to survival. The properties of vision are those needed to carry out significant activities such as seeking food, shelter and sex, so that individuals can survive and reproduce. That is, vision and the other senses have evolved to extract information regarding the constant properties of objects despite the changing patterns of stimulation at the sensory surfaces. Thus, object constancies are at the very heart of perception and in this chapter we will examine aspects of object perception before considering the more complex issue of perceiving pictures.
