One of the ideas I've mentioned has to do with the supposed reading of colors by the fingers. Below are two links:1st link:
FINGER PERCEIVES THE LIGHT
Rosa feels the colour of the light, penetrating through light filters and falling onto her fingers. Rosa says: " This ray is red, that ray is green; that one is orange, and the other one is blue". Moreover, she is able to identify not only a bright ray of light, but a weak one as well. She can even better identify coloured rays, let through the lens filled with water and then reflected on her hand with a mirror....
(a more critical) 2nd link:
....From 1960 to the present, research conducted in the USSR, United States, England and France, have showed that the skin is sensitive to far infrared invisible radiations of the electromagnetic spectrum.
Dermo-optical sensitivity refers to the human organism's capacity to respond to colored surfaces, hidden from sight by being placed under screens, even when the latter are held at some distance in the dark.
Dermo-optical perception refers to the ability of subjects to succeed in consciously differentiating these surfaces through their hands by non-visual subjective impressions. It is estimated this can only be done by one in six subjects. Controlled studies indicate support for the theory of dermo-optical sensitivity and perception. This finding provides a new potential confounding variable in color research. (int j Biosocial Res., 7(2); 76-93,1985.)....