Results
We found that in all instances visual contrast between adjacent UV+ and
UV- color patches was high, with JND values well above the conservative
discrimination threshold (JND = 3, Table 1). However, when comparing
between UV-sensitive and VIS-sensitive models, we found that although
achromatic contrast was nearly identical between the two models, there
were differences in chromatic contrast (Table 1). For all comparisons
chromatic contrast was higher in the UV-sensitive model, although the
magnitude of the effect varied by taxa. Moreover, when considering each
species/subspecies individually we found that the magnitude of the
difference between UV and VIS models was very high for butterflies but
comparatively low for frogs in both relative and absolute terms (Figure
1, Table 1).