75th anniversary of the Stiles–Crawford effect(s): a celebratory special symposium: October 23 2008, Rochester, New York

Abstract

There are rather few articles which, so to speak, serve to change the landscape in a scientific field. One of those was the discovery of the ‘directional sensitivity of the retina’ by Walter Stanley Stiles and Brian Hewson Crawford (first reported in 1933). Subsequently, their findings were subdivided by Hansen into two logical components, ‘the Stiles–Crawford Effects of the First and Second Kinds (SCE-1 and SCE-2)’. The former (SCE-1) dealt with aspects of their research which addressed alterations in perceived brightness of a visual stimulus; the second (SCE-2) was associated with the perceived hue and saturation of these visual stimuli. These discoveries arose out of a failed attempt by W.S. Stiles and B.H. Crawford to measure properly the areas of the entrance pupils of their experimental subjects as part of a research program which addressed problems of glare, e.g. disability glare in illuminating engineering. Their research was conducted at the National Physical Laboratory (NPL), which is located in Teddington, Middlesex, England. These two fine scientists properly deduced the reason for the failure of their experimental design, and they effectively described and defined a new feature of the visual system which was largely ascribed to the retina. In time, it was realized that this phenomenon was associated in large measure with the waveguide/fiber-optics properties of photoreceptors, and that this was a feature shared by virtually all vertebrate species. This paper is divided into two parts. In the first part, Enoch describes, as best he can, the culture and working conditions at NPL during 1959/60 when he served as a post-doctoral fellow with W.S. Stiles. And in the second part of this paper, the authors describe the findings of W.S. Stiles and B.H. Crawford at the time of their discovery. Today, we celebrate the 75th anniversary of that research. The organizing committee for this program (alphabetically) is David Atchison, Jay M. Enoch, Vasudevan Lakshminarayanan, and Pieter Walraven. Our group of speakers today will follow with discussions of aspects of subsequent work which has evolved from the initial discoveries made by the late W.S. Stiles and B.H. Crawford.

Keywords:

• photometry
• Stiles–Crawford effect of the first kind
• Stiles–Crawford effect of the second kind
• directional sensitivity of the retina
• NPL trichromator
• Maxwellian view