Scientists rely on animal models to gain insight into how humans learn language, but it turns out that one of their favorite models, the zebra finch, has been entirely misunderstood.
New research reveals that these birds don鈥檛 simply learn their songs by imitating adults: They learn by watching their mothers鈥 reactions to their immature songs.
In 鈥,鈥 published Jan. 31 in Current Biology, co-authors , associate professor of psychology, and doctoral candidate Samantha Carouso-Peck solve the mystery of why juvenile male zebra finches learn to sing better when females are around, even though the females don鈥檛 sing.
The researchers found that the adult females guide juveniles鈥 song development through specific interactions, similar to how human babies learn to talk. This study brings the number of species known to engage in socially guided vocal learning to four: zebra finches, humans, marmosets and cowbirds.
The researchers鈥 clue to the zebra finch mystery came when they considered that birds see the world at several times the 鈥渃ritical flicker fusion rate鈥 of humans. Simply put, birds can perceive events that happen much too fast for a human to see, and most previous research on social learning has not taken into account such rapid 鈥渂ird time,鈥 in which tiny behaviors can have large social effects.
Using slowed-down video, the Cornell researchers were able to identify tiny movements, imperceptible to the human eye, made by the female zebra finches to encourage the baby songbirds. These included wing gestures and 鈥渇luff-ups,鈥 an arousal behavior in which the bird fluffs up its feathers.
Researchers identified tiny movements, imperceptible to the human eye, made by female zebra finches to encourage baby songbirds. These included wing gestures and 鈥渇luff-ups,鈥 seen here, an arousal behavior in which the bird fluffs up its feathers.
鈥淥ver time, the female guides the baby鈥檚 song toward her favorite version. There鈥檚 nothing imitative about it,鈥 said Carouso-Peck.
The study included nine pairs of zebra finches, genetic brothers raised for the first 35 days by their respective parents. When they reached the age at which they begin to produce practice song (subsong), the siblings were split up, moved into individual soundproof containers and randomly assigned to one of two conditions: 鈥渃ontingent鈥 or 鈥測oked.鈥
Contingent birds were monitored by Carouso-Peck, and each time they sang in a way that matched their fathers鈥 song, she triggered a video playback of a female performing a fluff-up. The yoked bird saw the same fluff-up video at the same time as his contingent brother, but from his perspective the fluff-ups happened at random times unrelated to his song production.
A male zebra finch watches a video monitor displaying a female finch performing an arousal behavior called a 鈥渇luff-up. Credit: Michael Goldstein
After the birds鈥 songs 鈥渃rystallized鈥 into the final version, the researchers compared them to the songs of the juveniles鈥 fathers. They found that the birds in the contingent group learned significantly more accurate songs than their yoked brothers. Had the traditional model of song learning as pure imitation been correct, both birds would have learned the same song, because they had the same opportunity to memorize it early and practice it, according to Goldstein.
One possible reason for the zebra finch learning style, according to the researchers, is that because zebra finches use their songs to attract mates rather than defend territory, integrating female preferences into song is 鈥渁 highly adaptive strategy for future reproductive success,鈥 they wrote.
Researchers identified tiny movements, imperceptible to the human eye, made by female zebra finches to encourage baby songbirds. These included wing gestures and 鈥渇luff-ups,鈥 seen here, an arousal behavior in which the bird fluffs up its feathers.
鈥淗istorically we鈥檝e been studying these birds in isolation. That means we鈥檝e been missing out on the entire social aspect of song learning,鈥 Goldstein said.
Similarly, he said, most labs study human babies more or less in isolation.
鈥淏ut what babies 鈥 zebra finch or human 鈥 are good at is exploiting social information in their environment,鈥 Goldstein said. 鈥淭hese immature behaviors are not mindless practice and noise. Their function is to motivate the adults in the room to provide information.鈥
Zebra finches are widely used in research of vocal learning and production as well as research on Parkinson鈥檚 disease, autism, stuttering and genetic disorders of speech. 鈥淚ncorporating social factors into studies of zebra finch learning will strengthen the species as a model system,鈥 the paper鈥檚 authors write, 鈥渁s it will uncover new possibilities for drawing parallels with human speech acquisition.鈥
The research was supported by the National Science Foundation and Cornell鈥檚 Institute for the Social 麻豆视频.
More News from A&S
Government
