It may seem intuitively simple, but scientists have been puzzled by how the human brain is able to selectively focus on one voice from among the tangle of other voices and sounds. New findings are providing evidence that humans are not alone in that ability.
Like humans, birds can easily pick out and concentrate on a specific sound amid a cacophony of many sounds, a "cocktail party effect" for bird song, Johns Hopkins University psychologists have found.
"The issue here is, how can the bird hear these significant events in the midst of other noises, which are other potentially significant signals?" said Stewart Hulse, an experimental psychologist at Johns Hopkins. "It's just something the brain does. It can disambiguate these sounds, and yet the acoustical signal is an incredible mixture of many different sounds."
Hulse discovered that European starlings were able to accurately pick out specific bird songs mixed with other songs. They were successful even during the "dawn chorus," the combination of sounds heard in the forest during a spring morning, when all the birds are singing at once.
The findings are detailed in a paper to be published in the March issue of the Journal of Comparative Psychology. They may help scientists analyze how animals and people accomplish the feat and draw further parallels between human and non-human perception. The paper was written by Hulse, who is a professor in the Department of Psychology, and graduate students Scott MacDougall-Shackleton and Amy Wisniewski.
The scientists combined the tape-recorded songs of starlings, brown thrashers, nightingales and mockingbirds. The starling and brown thrasher songs were paired together, as were the songs of nightingales and mockingbirds.