Fig. 3. Averaged responses of wolf spiders to the stimulus described in Fig.2. Responses before (open columns) and after (grey columns) rotation of either a neutral density filter (control) or a polarizer (test) are shown for either clockwise (N=9) or counterclockwise (N=11) rotation of the filter. In both cases, P values show the statistical significance of the difference in rotational response of the spider (Student’s paired t-test). Values are means ± S.E.M.