A battery of tests using newly-developed cone-isolating flicker large-field ERG recordings showed, amongst other things, that the function of his long-wavelength-sensitive cones was completely absent. In other words was he was indeed a ‘protanope‘. See: Detecting color vision in a malingerer in : Documenta Ophthalmologica, March 2003, Volume 106, Issue 2, pp 121-128
Question: Could an alternative title for the paper be ‘Failure to detect color vision in a non-malingerer’?
Bonus: Three of the authors also contributed to a later study : Visual short-term effects of viagra: double-blind study in healthy young subjects in: American Journal of Ophthalmology, Volume 137, Issue 5, May 2004, Pages 842–849
[photo courtesy Martin Howard / Wikipedia]