A) Normalised spectral responses averaged over:

*top*) 12 hemispheric cells and bottom) 14 mid-band cells, rows 5 and 6. B) Response vs. time for a row 5 R3 photoreceptor when illuminated with a 50 ms spectrally-filtered light pulse:

*left*) left-circular,

*l*;

*right*) right-circular,

*r*, polarisation. This cell responds more strongly to

*l*. C), D), Peak response vs. polariser angle for R1 cells in the C) dorsal and D) ventral hemispheres. These act as anti-diagonal and horizontal polarising photoreceptors, respectively. The smooth pink lines are logarithmic cosine-squared curves with 4 fit parameters (phase, cosine amplitude, response offset, and logarithmic amplitude). E), F), Peak response versus relative light intensity for the C) and D) cells. Top curves are measured at the maximum response angle, φ

_{max}; bottom at φ

_{min}. The smooth lines are sigmoidal curves fitted to a Naka-Rushton function using least-squares approximation in Origin 6.1. The polarisation sensitivity,

, is measured by taking the difference between intensities in the linear part of the curves, δ

_{i}. G), H), Peak response versus relative light intensity for a row 5 R1 cell. G) Response to left (top curve) and right (bottom curve) circularly polarised light. H) Response to linearly polarised light ±45° from the vertical—to within error there is zero linear polarisation sensitivity.

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