Variations in normal color vision. I. Cone-opponent axes

Area of Science:

• Vision Science
• Psychophysics
• Neuroscience

Background:

• Early postreceptoral color vision models utilize two main axes: L-vs-M (opposing long and medium cone signals) and S-vs-LM (opposing short cone signals by combined long and medium cone signals).
• These cone-opponent axes are foundational in color vision research but are often defined theoretically using a standard observer, potentially overlooking individual variability.

Purpose of the Study:

• To investigate the extent and consequences of interobserver variations in cone-opponent axes.
• To empirically define the L-vs-M and S-vs-LM axes and assess sensitivity to them across individuals.

Main Methods:

• Employed chromatic adaptation techniques to empirically determine individual L-vs-M and S-vs-LM axes.
• Utilized detection thresholds and color contrast adaptation to measure sensitivity to these axes.
• Analyzed individual color matching data (Stiles and Burch, 1959) to infer axis variations.

Main Results:

• Empirically estimated cone-opponent axes for individuals showed measurable deviations from standard observer axes.
• Individual axis variations can influence the interpretation of postreceptoral color organization, including interactions between axes.
• Differences in chromatic sensitivity, akin to luminance sensitivity variations, are significant.

Conclusions:

• Individual differences in cone-opponent axes are significant and should be considered in color vision research.
• Empirical determination of these axes provides a more accurate basis for understanding individual color perception.
• Accounting for interobserver variability enhances the precision of models of postreceptoral color organization.