Barn Owls detect horizontal sound changes

From nature.com:

Barn owls are better at tracking sounds that move horizontally than those that move vertically, researchers have found. The technique used to make the discovery could one day be used to assess hearing and cognitive skills in humans who cannot communicate.

The work, published in PLoS ONE, relies on a phenomenon noted by Ivan Pavlov, of salivating dog fame, in the 1920s. Pavlov saw that animals respond to stimuli such as sudden movements or novel noises with a set of automatic responses, including muscle tensing and pupil dilation.

Avinash Bala, a neurologist at the University of Oregon in Eugene, and his colleagues have used this response to monitor when barn owls (Tyto alba) recognize a new sound.

The researchers played the owls sounds whose positions differed either horizontally or vertically, and measured the birds' pupil dilation using a beam of infrared light bounced off the cornea.

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