Polarized light discrimination by pigeons and an electroretinographic correlate.

Pigeons placed in a multiple-key Skinner-box could be trained to choose reliably keys that were aligned in a specific way with the polarization axis of an overhead, randomly rotating light source. On the basis of these results and those of additional control experiments, it is concluded that pigeons can discriminate the axis orientation of linearly polarized light and, furthermore, that they can orient themselves spatially by this cue. Electrophysiological recording experiments showed that the shape of the b-wave of the pigeons' electroretinogram is affected by the axis orientation of linearly polarized flash stimuli. This phenomenon seems to be due to the presence of retinal polarization analyzers that may be tied to color vision mechanisms.