Cornell BABY Lab

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From Nest to Nursery: How Feedback Shapes Voices

Is it possible that two very different species - such as birds and humans - have something similar in how they learn to communicate? The answer is a resounding yes! According to our recent paper in Philosophical Transactions of the Royal Society B, both human infants' speech development and zebra finch bird song development are shaped by their social interactions—more specifically, by the social feedback they receive in response to their immature vocalizations.

In our two studies on infants, we had parents play with their infants for 15 minutes. We found that infants who produced sequences of sounds rather than singular syllables were more likely to elicit a response from their caregivers. Additionally, when caregivers responded to these infants, the infants were more likely to produce vocal sequences than singular syllable sounds. This creates a feedback loop between infants and their caregivers.

Over time, we noticed that infants who experienced higher caregiver responsiveness actually improved their language development as a result. They showed more vocal compression at 10 months and a larger vocabulary size at 18 months. This means that caregiver responsiveness is crucial in the development of children’s communication abilities.
We observed the same phenomenon in birds. In our experiment, Juvenile zebra finches who practiced their immature song and either received or did not receive contingent social feedback. Those that received contingent responses from female caregivers were the only ones to significantly develop their vocal compression, while birds that did not receive contingent responses from caregivers did not. Only the birds who received contingent responses to their vocalizations were able to produce a similar bird song as their “tutor”, meaning it was caregiver responses that predicted vocal maturity.

For more detailed methods and discussion, please feel free to read the full article linked below. To find out more fun studies like this one, follow our Instagram and Facebook to catch up on the newest research in our lab!

The social origins of vocal sequences in songbirds and human infants Abstract. From birdsong to human language, acoustic communication by vocal learners involves the concatenation of sounds into sequences. Sequences are more

How do languages become learnable for young children? Our latest study,‬ "Immature‬ vocalizations elicit simplified adult speech across multiple languages," is now out in‬ Current‬ Biology‬!‬

We’ve long known that infants and toddlers are incredible learners. Despite their immaturity, do they play an active role in their learning? We found that the answer is yes. Our new study shows that infants’ and toddlers’ early babbling and immature speech functions to facilitate caregivers’ reactions that help them learn. When caregivers respond to immature speech, they speak in simpler sentences. This “simplification effect” from caregivers‬ makes language more learnable! We found this effect in 13 different languages, including Tseltal Mayan, where engaging in face-to-face interaction with infants is rare. What such cross-cultural behavior‬ implies is that this "simplification effect” may be widespread and present in many more languages than the 13 we‬ studied.‬

We found that the timing of parents’ responses matters. Parents simplified their speech significantly more when they responded immediately (i.e. contingently) after their child’s babbling and speech. In contrast, infant-directed speech that was not contingent was not simplified.

Read more about our findings in the Cornell Chronicle: https://news.cornell.edu/stories/2025/02/power-babble-babies-elicit-simpler-speech-adults

Current Biology article: https://www.cell.com/current-biology/fulltext/S0960-9822%2824%2901720-2