In what is either a sign of their amazing intelligence or massive confusion, babies between the ages of three and six months old are just as excited by the call of the blue-eyed Madagascar lemur as by the voices of their own mothers, a Northwestern University clinical psychologist found in a recent study.
In the study, babies were given the task of responding to different images while listening to sounds of human baby talk. They also listened to artificial speech-like sounds, including speech played backward. Finally, the infants listened to the call of the lemur (picture of lemur at right).
The test was designed to show how well the 72 infants in the study remained engaged with the images while the different sounds played. According to researcher Sandra Waxman, a professor of cognitive psychology at Northwestern, the babies tended to tune out when listening to artificial voices.
But the human voices and lemur calls both focused the babies’ minds in the same way.
"They were doing some much fancier cognitive dancing during the lemur and human vocalization than in the case of backward speech or tones," Waxman said to NBC News. "The fact that there's this precocious link between language and thought ... it's just hands-down amazing."
But when Waxman included babies aged 6 months or older in the study, she obtained a different result. That’s the age, the study found, when babies start to tune out vocal sounds that are recognizably non-human.
Waxman theorized that babies lost their responsiveness to the lemur calls around the age of six months because by that time, they have heard enough humans speech to distinguish it from other forms of communication.
Waxman is now studying whether playing lemur calls for the older babies on a nightly basis will cause them to retain their sensitivity to the primate communication.
SOURCES: NBC News, Daily Mail