We evaluated binocular summation, eye dominance, and learning in the
Trivector and Ellipses procedures of the Cambridge Colour Test (CCT).
Subjects (n = 36, 18–30 years old) were recruited among
students and staff from the University of São Paulo. Inclusion
criteria were absence of ophthalmological complaints and best-corrected
Snellen VA 20/20 or better. The subjects were tested in three randomly
selected eye conditions: binocular, monocular dominant eye, and
nondominant eye. Results obtained in the binocular and monocular
conditions did not differ statistically for thresholds measured along the
protan, deutan, and tritan confusion axes (ANOVA, P > 0.05).
No statistical difference was detected among discrimination ellipses
obtained in binocular or monocular conditions (ANOVA, P >
0.05), suggesting absence of binocular summation or of an effect of eye
dominance. Possible effects of learning were examined by comparing
successive thresholds obtained in the three testing conditions. There was
no evidence of improvement as a function of testing order (ANCOVA,
P > 0.05). We conclude that CCT thresholds are not affected by
binocularity, eye dominance, or learning. Our results differ from those
found by Verriest et al. (1982) using the
Farnsworth-Munsell 100 Hue test and Hovis et al. (2004) using the Farnsworth-Munsell panel D-15
test.