- Caregivers use tightly coordinated and expressive speech and facial expressions when engaging their infants.
- Over the first 12 months, infants shift their attention from a speaking caregiver's eyes to their mouth.
- Attending to a speaker's mouth gives older infants visual speech cues to support their language learning.
- Singing to infants captures infants' attention and influences how they attend to their caregivers' face.
Co-authored by Camila Alviar, Ph.D. and Miriam Lense, Ph.D.
Infants all over the world become masters of the language their community speaks within the first 3 years of life, a surprisingly short time given the complexity of the task. Several ingredients are responsible for their impressive language development skills: infants are born with attentional biases that make them tune into social and linguistic signals, and their young brains are equipped with incredible pattern recognition skills to help them learn specific sounds and structures from the speech they hear.
But it’s not just about the skills of the infant. Caregivers naturally modify their speech when engaging with babies compared to when they speak with other adults (or even older children who are already language experts). This “baby talk” (also known as infant-directed speech) helps young children attend to and process speech.
When speaking to infants, adults make their speech more musical; they raise the pitch of their voice and increase the variability of their vocal pitch, exaggerate the different speech sounds, and make their phrases a lot simpler, more repetitive, and more rhythmic.
And it’s not only the spoken part of the communication that matters. Adults accompany this auditory speech performance with non-verbal cues that involve simplified but exaggerated movements and gestures and positive and caring facial expressions. Even their head nods and eyebrow movements are carefully, though unconsciously, coordinated with the pauses and pitch changes in their speech.
Infants are therefore provided with rich, multisensory cues to the meaning of the message, and to the vocabulary, structure, and grammatical rules of the language they are learning.
Infants learn language in part by paying attention to caregivers' faces.
Infants’ attention to the face of their engaging caregiver changes dramatically across the first year of life. During the first half of the first year, infants mostly attend to the eyes of the caregiver who is speaking to them.
Looking to the eyes of speakers gives babies information about the emotions and intentions of the people around them. It also helps to establish shared attention; when infants and caregivers pay attention to the same thing at the same time, it helps infants know that what they are paying attention to is important and meaningful.
In the second half of the first year, babies start to hone in on the specific patterns in the speech they are hearing so they can learn the language(s) that surround them. They increasingly engage in babbling, first by combining single vowel and consonant sounds (e.g., ba) and then stringing the sounds together (e.g., dadadada). Babbling lets babies practice speech sounds and communicate with others around them.
During this period, their interest shifts from the eyes to the mouth of the person speaking to them. By focusing their visual attention on the mouth, the infant receives redundant and complementary auditory and visual information about the speech they are hearing. Looking to the mouth of speakers during this developmental period is related to vocabulary size and language comprehension in toddlerhood, suggesting this attentional shift is helpful for language development.
Singing captures and directs infants' attention to caregivers' faces.
In addition to speaking to infants, caregivers across the world also engage infants through singing. Particularly when infants can both hear and see the person engaging them, infants attend longer when someone sings to them rather than speaks to them. But what precisely do infants look at when someone sings to them?
In a recent study in Developmental Science, infants viewed videos of actresses engaging them with speech and song. Eye-tracking technology captured where infants attended for every frame of the video.
As in previous studies of speech across the first year of life, infants shifted their attention from mostly looking at the eyes to mostly looking at the mouth of the actress. But this shift occurred earlier in development and to a greater extent for song than speech. That is, infants look at the mouth of someone engaging them more for song than speech.
What about song makes the mouths of singers so interesting for babies? Take a moment and sing the opening phrase of “Twinkle, twinkle little star,” using the well-known and well-loved melody. (Sing to your baby if they're with you!) Now recite the same phrase using speech (not singing or chanting). What do you notice?
Singing modifies the cues a caregiver provides to an infant.
Was your singing rendition slower than your spoken rendition? Was it more rhythmically predictable and evenly timed? Did your mouth move more leading to greater synchrony between your mouth movements and your voice?
It turns out that all these aspects of communication promote infants’ attention to someone’s mouth. This is particularly meaningful during the latter half of the first year when infants are babbling and preparing to say their first words because it highlights the mouth movements that are used as part of producing speech, and it also calls attention to the bursty stop and start pattern of speech and pauses.
(You may also have noticed you were smiling more during your singing version. Caregivers tend to smile more when playfully singing with their infant and this also promotes infant mouth-looking but more so during the first months of life, when singing’s role is primarily for supporting social and emotional bonding between infant and caregiver.)
It's too early to know if this increased mouth-looking by infants during song is also helpful for language learning as it is during speech, a question for future research. But song appears to be a particularly powerful way to attract infants’ attention and naturally guide their looking behavior.
What to try at home
You can engage with your baby and support their development by speaking and singing to them face-to-face every day. These face-to-face interactions give babies visual cues to support their attention and learning.
It might also be fun to sing to your infant while looking in a mirror together so that your baby (and you!) can notice how your facial expressions and movements change as you switch between singing and speaking to them. Try singing songs like “If You’re Happy and You Know It” using the lyrics below to play around with acting out different emotions as you sing, making your face very expressive and engaging to your baby.
If You’re Happy and You Know It (emotions version)
If you’re happy and you know it, share a smile (repeat x3)
If you’re sad and you know it, get a hug (repeat x3)
If you’re mad and you know it, take a breath (repeat x3)
Alviar, C., Sahoo, M., Edwards, L. A., Jones, W., Klin, A., & Lense, M. (2023). Infant‐directed song potentiates infants’ selective attention to adults’ mouths over the first year of life. Developmental Science, 26(5), e13359.
Lewkowicz, D. J., & Hansen-Tift, A. M. (2012). Infants deploy selective attention to the mouth of a talking face when learning speech. Proceedings of the National Academy of Sciences, 109(5), 1431-1436.
Tenenbaum, E. J., Sobel, D. M., Sheinkopf, S. J., Malle, B. F., & Morgan, J. L. (2015). Attention to the mouth and gaze following in infancy predict language development. Journal of Child Language, 42(6), 1173–1190.