Related Experiment Video
Updated: May 1, 2026

Generating Strictly Controlled Stimuli for Figure Recognition Experiments
Published on: March 18, 2019
Symmetries and asymmetries in chromatic discrimination
Abstract:
Under conditions of adaptation to a steady neutral field (metameric to Daylight Illuminant D65), forced-choice thresholds for color discrimination were measured for brief targets presented to the human fovea. Measurements were made along +45° and -45° lines in a MacLeod-Boynton chromaticity space scaled so that the locus of unique yellow and unique blue lay at -45°. The lines were symmetrical relative to the tritan line passing through the chromaticity of D65. Thresholds increased with distance of the probe chromaticity from D65. Thresholds were higher for saturation discrimination than for hue discrimination. A region of enhanced discrimination was found for thresholds measured orthogonally to the locus of unique blue and unique yellow. There may be an analogous enhancement near the loci of unique red and unique green.
Related Concept Videos
Color Vision
Photoreceptors and Visual Pathways
Chirality
Chiral objects exhibit a sense of handedness when they interact with another chiral object. For example, our left foot can only fit in the left shoe and not in the right shoe. Achiral objects — objects that have...
Gestalt Principles of Perception
Prochirality
Stereoisomerism
Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...

