Fig. 4.

Detection of coloured patterns by honeybees. Patterns composed of two colours which had the same L-receptor contrast (right column) were detectable until 5° of visual angle, whereas patterns in which L-contrast was varied were detected over shorter distances. Red frames depict angular sizes at which patterns were not detected although equal numbers of ommatidia were excited above threshold. After Hempel de Ibarra et al. (2001)