Temporal resolution of colour vision in the honeybee

The temporal resolution of colour vision was measured in freely-flying honeybees by testing the performance of trained bees in discriminating between two stimuli, one of which presented a steady, homogeneous mixture of two colours, while the other offered a heterochromatic flicker between the two colours at various temporal frequencies. Pairwise combinations of the colours uv, blue and green were used, corresponding to the three receptor classes in the bee retina. For each colour combination, we determined a cutoff frequency beyond which discrimination no longer exists. For a given colour combination, the cutoff frequency depends upon the ratio of the intensities of the component colours, and is maximum at a particular ratio. The cutoff frequency at the optimum intensity ratio is approximately 100 Hz for each of the 3 colour combinations blue-green, green-uv and uv-blue, implying that colour computation requires ca. 10 ms. From the optimum intensity-ratios for the three colour combinations, we infer that the relative sensitivities of the green, blue and uv channels are approximately 1:1.3:24.