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

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...