Figure 6.

Results of Experiment 4, in which bees flew in a tunnel with transversely polarized illumination in the first half and axially polarized illumination in the second half, as depicted by the lines in the ceiling in (a). This arrangement mimics the overhead illumination that a bee would experience if it were to fly initially in a direction directly away from the sun, as shown in (b), or directly towards it, and subsequently in a direction such that the sun is 90° to the right, as shown in (b), or 90° to the left. In (c), the thin lines (blue in the online version) depict the dance orientation histogram. The thick continuous lines (red in the online version) show the four modal dance directions, computed as described in §2. The thick broken lines (green in the online version) show, for comparison, the four principal diagonal directions: 45°, 135°, 225° and 315°. (Online version in colour.)