送交者: Latino2 于 2005-1-13, 19:24:05:
外语是老鼠斗争的一种武器。 －－ 毛泽东
Are Rats Bilingual?
To us, all rat squeaks may sound alike, but the same may not hold true
for the rodents. A new study reveals that rats are able to tell the difference
between spoken Dutch and Japanese-a skill previously thought to be shared
by only humans and tamarin monkeys.
One way to help figure out how language evolved in humans is to study the
language-related abilities of other animals. Tamarin monkeys pick up patterns
in language from rhythmic cues such as stress and intonation, just as human
infants do, but scientists have wondered if other animals can use similar
cues to discriminate between different languages.
To test this, a research team led by neuroscientist Juan Toro from the University
of Barcelona trained a group of rats to press a lever after they heard synthesized
sentences of Japanese or Dutch--languages spoken with very different intonation,
stress, and phrasing. Once trained, animals familiar with one language stopped
pressing the lever when they heard the other language. They resumed pressing
the lever once their "own" language started playing again.
The rats were hearing cues specific to language, the researchers say. In
another experiment, where the researchers trained a new group of rats with
Japanese and Dutch sentences played backwards and then tested their discrimination
ability, the rats were not able to distinguish between the two languages,
the team reports in this month's issue of the Journal of Experimental Psychology.
"Rats are able to find the differences between Dutch and Japanese sentences,
but whatever information they are using is lost in backwards speech," Toro
says. The missing cues are probably stress and intonation. Apparently, the
ability to recognize these patterns evolved long before language did.
Aaron Blaisdell, a psychologist at the University of California, Los Angeles,
notes that "the backward sentences were the really strong part of the test."
He says that any animal with the ability to time and perceive tone should
be able to discriminate languages with distinct rhythms.