Table 1.

Models of colour discrimination for the honeybee

Model	Publications	Basic assumptions
Maxwell triangle	Neumeyer (1981)	No specific colour-coding mechanisms
COC model (colour-opponent coding model)	Backhaus et al. (1987), Backhaus (1991)	Hyperbolic transformation of quantum catches; city-block metric
Hexagon model	Chittka (1992)	Hyperbolic transformation of quantum catches; euclidean metric
GCO model (general colour-opponent coding model)	Brandt and Vorobyev (1997)	Receptor signals are linear functions of quantum catches; riemannian metric
RNL model (receptor noise-limited colour-opponent model)	Vorobyev and Osorio (1998), Vorobyev et al. (2001a)	Receptor signals are given by logarithms of quantum catches; receptor noise limits discrimination: (a) with constant noise-to-signal ratio (receptor noise obeys Weber’s law), or (b) with square root noise-to-signal ratio (receptor noise obeys Rose–de-Vries law)