|
| |
|
|
|
|
||||
| Home Help Feedback Subscriptions Archive Search Table of Contents | ||||
|
Fig. 4. Haze experiment. (A) 180° fisheye view of the celestial hemisphere on a
hazy morning. Compared with clear atmospheric conditions, the degree of
polarization across the whole sky is reduced. (B,C) Polarotactic response as a
function of the degree of polarization for a uniform stimulus. The effective
degree of linear polarization (d) of a medium-sized (25°)
zenithal stimulus was reduced from d=100% to 0% by changing the
ellipticity of light (see Materials and methods). Test data (d=1% to
53%) are indicated by black, motivation controls (d=100%) by gray,
and zero controls (d=0%) by white (24 series of 17 individuals). (B)
Survey of results. Relative strength of the polarotactic response
(S/Smot; mean ± s.d.) plotted against the
effective degree of linear polarization. (C) Distribution of S-values
and (D) modulation of walking direction with stimulus orientation for some of
the polarization levels tested (see polarization ellipses to the left). Data
in D are normalized and plotted as described in
Fig. 3D. Note: a reduction in
polarization to d=53% did not impair the polarotactic response. With
lower d-levels, the response strength decreased. However, there was a
statistically significant orientation to polarized light at least down to a
d-level of 7% (P<0.01).
|
