On the Physical Origins of Inverted Optic Images

In the behavioral sciences, discussions of vision often carry an implicit assumption that the formation of inverted optic images is a result of human technology (i.e., cameras) or biological mechanisms (i.e., the chambered eye). If this assumption were true, then inverted images would be—in effect—an invention of living things, which, in turn, would have important consequences for our understanding of the evolution and psychology of vision. In this article, I briefly review the history of ideas relating vision and optics to the formation of inverted optic images. I then evaluate the necessary and sufficient conditions for the formation of inverted images. I demonstrate that inverted optic images (including inverted optic flow) can and do form in the absence of any biology and that sufficient conditions for inverted image formation predate the origins of life. Inverted images are not an invention of biological systems; rather, biological systems and human technologies exploit preexisting facts of physical optics. This conclusion is consistent with the ecological premise that life is coherent with physical law.