Songbirds learn 'grammar' of warbles
posted 2006-05-02 03:07:11 latest updated 2006-05-02 14:27:39
linguistics Grammar students in grade school should put away their excuses. Scientists say even a bird brain can grasp one of grammar's early concepts.
Researchers trained starlings to differentiate between a regular bird song "sentence" and one that was embedded with a warbled clause, according to research in last week's issue of the journal Nature. This "recursive grammar" is what linguists have long believed separated man from beast.
It took University of California at San Diego psychology researcher Tim Gentner a month and about 15,000 training attempts, with food as a reward, to get the birds to recognize this grammatical structure in their own bird language.
What they learned may shake up the field of linguistics.
While many animals can roar, sing, grunt or otherwise make noise, linguists have contended for years that the key to distinguishing language skills goes back to basic grammar.
Recursive grammar — inserting an explanatory clause like this one into a sentence — is something that humans can recognize, but not animals, researchers figured.
Two years ago, a top research team tried to get tamarin monkeys to recognize such phrasing, but they failed. It was seen as upholding famed linguist Noam Chomsky's theory that recursive grammar is uniquely human and key to the facility to acquire language.
However, after training, nine out of Gentner's 11 songbirds picked out the bird song with inserted warbling or rattling bird phrases about 90 percent of the time.
"We were dumbfounded that they could do as well as they did," Gentner said. "It's clear that they can do it."
Gentner trained the birds using three buttons hanging from the wall. When the bird pecked the button it would play different versions of bird songs that Gentner generated, some with inserted clauses and some without.
If the song followed a certain pattern, birds were supposed to hit the button again with their beaks; if it followed a different pattern they were supposed to do nothing. If the birds recognized the correct pattern, they were rewarded with food.
Gentner said he was so unprepared for the starlings' successful learning that he hadn't bothered to record the songs the starlings sang in response.
"They might have been singing them back," Gentner said.
To put the trained starlings' grammar skills in perspective, Gentner said they don't match up to either of his sons, ages 2 and 9 months.
What the experiment shows is that language and animal cognition is a lot more complicated than scientists once thought and that there is no "single magic bullet" that separates man from beast, said Jeffrey Elman, a professor of cognitive science at UCSD, who was not part of the Gentner research team.
Marc Hauser, director of Harvard University's Cognitive Evolution Laboratory, who conducted the tamarin monkey experiment, said Gentner's study was important and exciting, showing that "some of the cognitive sources that we deploy may be shared with other animals."
SETH BORENSTEIN chron.com/Associated Press
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