As you’ve probably noticed, very young babies would rather listen to human speech (especially yours!) than just about anything else. Developmental psychologists have been surprised to discover, however, that newborns prefer listening to both human language andnonhuman primate vocalizations over other interesting sounds. What’s more, in the first months of life they also prefer looking at both human faces andnonhuman primate faces. And at our research center at Northwestern University, we’ve shown that at three months old, babies don’t just prefer human and nonhuman primate sounds; they link these sounds to meaning! Infants listening to human language and lemur calls are able to successfully perform cognitive tasks that they do not succeed at while listening to other interesting sounds like birdcalls or musical tones.
So if listening to monkey calls helps your 3-month-old perform cognitive tasks, will it also help her perform arithmetic as a 7-year-old? Sadly, no; we’ve learned from our research that this initially broad set of preferences and abilities is also sculpted by experience. At 6 months of age, infants that were able to tie monkey calls to meaning just a few months earlier have already lost this ability. Instead, they are tuning into the relevant sounds in their environment as they become experts in their own native languages. Recently, a researcher at our center, Danielle Perszyk, asked whether brief exposure to lemur vocalizations at an age after babies have tuned out the link to meaning might enable them to reinstate this link.
To test this possibility, she created a 10-minute recording of classical music interspersed with lemur calls. The 6-month-olds in the study listened to this wild soundtrack and then participated in a cognitive looking task. Astonishingly, we found that just this small period of exposure restored the developmentally prior link for these infants, allowing them to successfully perform the task that those without exposure could not!
“While infants are exquisitely sensitive to postnatal experience, they also remain extraordinarily flexible learners early in development, easily re-instating links that have been lost,” says Perszyk. “It is this very plasticity that also guides them to precisely tune into more meaningful, communicative sounds, allowing them to master their native tongue within only a few years.”