Difference in perception of unpolarized and polarized light What is the difference in perception of polarized light and unpolarized light? What difference does polarized light cause to our eyes?
 A: There is some evidence of polarization  perception.

Many people are able to perceive
  polarization of light. It may be seen as a
  yellowish horizontal bar or bow-tie shape
  (with "fuzzy" ends, hence the name
  "brush") visible in the center of the visual
  field against the blue sky viewed while
  facing away from the sun, or on any bright
  background. It typically occupies roughly
  3–5 degrees of vision, about the same
  size as the tip of one's thumb held at
  arm's length. The direction of light
  polarization is perpendicular to the yellow
  bar (i.e., vertical if the bar is horizontal).
  Fainter bluish or purplish areas may be
  visible between the yellow brushes (see
  illustration). Haidinger's brush may also
  be seen by looking at a white area on
  many LCD flat panel computer screens
  (due to the polarization effect of the
  display), in which case it is often diagonal.

See, for instance, Haidinger's brush on Wikipedia.
A: Our eyes cannot see any difference between ordinary (i.e., unpolarized) and polarized light. You can check it yourself, if you look through a polarizer (for example, some sunglasses have one). All you can notice is that the world gets slightly darker (because you block roughly half the incoming light). In addition, some reflections might be reduced dramatically (that is, after all, one of the main points in using polarizers in sunglasses).
There are, however, other species (e.g., bees, as far as I know) that can see the difference but, unfortunately, nobody has been able to ask them what such a difference looks like...
