Scopes of perception: the experimental manipulation of space and time.

Discussions of space and time have been grist to the philosophers' mill for centuries. We argue that the evolution of psychology as an independent discipline was in part a consequence of addressing philosophical questions concerning the perception of space and time by recourse to experiment rather than exposition. Two initially separate factors assisted in establishing this independence. On the one hand, it was driven by the invention of instruments for stimulus control so that the methods of physics could be applied to the study of perceptual phenomena. On the other hand and somewhat later, it was followed by the development of psychophysical methods, which opened the possibility of quantifying the responses to such controlled stimulation. The principal instruments were invented in the first half of the nineteenth century, and they consisted of simple contrivances that manipulated time and space in ways that had not previously been appreciated. This article examines the devices that were invented, like stroboscopes, anorthoscopes, stereoscopes, tachistoscopes, chronoscopes, and more recently oscilloscopes, and the ways in which they influenced the scope of perceptual psychology in the past as well as in the present. In contemporary experimental psychology all these instruments have been replaced by the computer. While it has extended the scope of experiments even further it has introduced a new set of limitations.