Behavioral and Brain Sciences

Continuing Commentary
Commentary on Stephen E. Palmer (1999). Color, consciousness, and the isomorphism constraint. BBS 22(6):923–989

Color, qualia, and psychophysical constraints on equivalence of color experience

Vincent A. Billock a1 and Brian H. Tsou a2
a1 General Dynamics, Inc., U.S. Air Force Research Laboratory, Suite 200, 5200 Springfield Pike, Dayton, OH 45431 [email protected]
a2 U.S. Air Force Research Laboratory, WPAFB, OH 45431 [email protected]


It has been suggested that difficult-to-quantify differences in visual processing may prevent researchers from equating the color experience of different observers. However, spectral locations of unique hues are remarkably invariant with respect to everything other than gross differences in preretinal and photoreceptor absorptions. This suggests a stereotyping of neural color processing and leads us to posit that minor differences in observer neurophysiology may be irrelevant to color experience.