Bow ties and cuttlefish: Researchers gain new insight into a visual super sense

http://www.eurekalert.org/pub_releases/2015-06/uob-bta062615.php

Public Release: 30-Jun-2015
University of Bristol

An experiment originally designed to test the visual abilities of octopuses and cuttlefish has given University of Bristol researchers an unprecedented insight into the human ability to perceive polarized light - the super sense that most of us don't even know we have.

We are all familiar with colour and brightness, but there is a third property of light, the 'polarization', which tells us the orientation in which the light waves are oscillating.

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Animals, like bees and ants, use polarization patterns in the sky as a navigation aid. But few, even in the scientific community, are aware that humans can perceive the polarization of light with the naked eye too. We do so using 'Haidinger's brushes', a subtle visual effect, which appears like a yellow bow tie at right angles to the polarization angle.

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Dr Temple explains: "You can see Haidinger's brushes if you look at a blank white portion of an LCD screen on a computer, tablet or phone. Tilt your head from side to side and faint yellow brushes should become visible. With practice, you can then see them in the blue parts of the sky at 90 degrees from the sun."

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