April 26, 2006
Songbirds May Be Able to Learn Grammar
WASHINGTON -- The simplest grammar, long thought to be one of the skills that separate man from beast, can be taught to a common songbird, new research suggests.
Starlings learned to differentiate between a regular birdsong "sentence" and one containing a clause or another sentence of warbling, according to a study in Thursday's journal Nature. 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 the most basic of grammar in their own bird language.Yet 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 our elementary school teachers and basic grammar. Sentences that contain an explanatory clause are 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. The results were seen as upholding famed linguist Noam Chomsky's theory that "recursive grammar" is uniquely human and key to the facility to acquire language.
But 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. Two continued to flunk grammar.
"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."
But Hauser said it still doesn't quite disprove a key paper he wrote in 2002 with Chomsky. The starlings are grasping a basic grammar, but not the necessary semantics to have the language ability that he and Chomsky wrote about.
Hauser said Gentner's study showed him he should have tried to train his monkeys instead of just letting them try to recognize recursive grammar instinctively. But starlings may be more apt vocalizers and have a better grasp of language than non-human primates. Monkeys may be trapped like Franz Kafka's Gregor Samsa, a man metamorphosized into a bug and unable to communicate with the outside world, Hauser suggested.