Better baby communication:
Has natural selection wired your brain for baby talk?
© 2008 -2014 Gwen Dewar, Ph.D., all rights reserved
Baby communication happens along several channels, including those of sight and touch.
But perhaps the most obvious way that parents communicate with their infants is by talking to them.
it “baby talk," “motherese," or “infant-directed speech" (IDS), this
style of speaking isn’t about repeating nonsense words or imitating the
baby’s attempts to talk.
It’s about using the same words we use in regular speech, but with distinctive modifications that make the message more clear.
Indeed, this special form of baby communication may be designed to
There’s even evidence that even adults learn a language more easily from people speaking in "motherese."
How baby communication reshapes the way we talk
It seems to happen automatically. When parents address their babies,
they may use the same words that they use to address other adults. But
they adopt a special style of speech (Kemler-Nelson et al 1989; Swanson and Leonard 1994; Fernald 2000; Christia and Siedl 2013; Saint-Georges et al 2003):
- Their voices become higher-pitched
- They use a wider pitch range (i.e., more distance between the highest- and lowest-pitched sounds)
- They exaggerate their emotional tone
- They speak in simpler, shorter utterances
- They use greater repetition
- They speak more slowly
- They give special emphasis to words by speaking them in isolation (“Ball!")
- And, if they are English-speakers, they may also exaggerate the articulation of certain vowel sounds and position target words at the end of a sentence (“Look at the BALL!")
Moms do it. Dads do it. Kids do it. People lacking experience with babies do it (Fernald et al 1989; Jacobson et al 1983).
What’s more, babies--even newborn babies--prefer to be addressed this way.
one experiment, researchers Robin Cooper and Richard Aslin presented
2-day old infants with audio recordings of adult speech.
The babies could control how long each playback lasted by turning their heads toward a loudspeaker.
In some trials, babies heard infant-directed speech. In other trials, they heard adult-directed speech.
Cooper and Aslin found that the newborns turned their heads longer in response to infant-directed speech (Cooper and Aslin 1990).
Similar experiments have been performed on older babies, with the same results. In one study, five-month-old babies showed a preference for strangers who addressed them with infant-directed speech, even after the talking had ended (Schachner and Hannon 2011).
the behavior of newborns seems especially compelling. It suggests that
babies are born with an unlearned preference for infant-directed speech.
A universal mode of baby communication?
Baby talk has been documented in wide range of languages, including languages indigenous to
- Africa and the Middle East (Arabic and Xhosa, a Bantu click language),
- The Americas (Comanche)
- Australia (Warlpiri)
- East Asia (Cantonese, Mandarin, Korean, Japanese, and Gilyak, a Siberian language)
- South Asia (Bengali, Hindi, Marathi, and Sinhala, a Sri Lankan language)
- Europe (English, French, German, Italian, Latvian, and Swedish)
references, see (Das 1989; Dil 1971, Ferguson 1964; Fernald et al 1989;
Fernald and O’Neill 1993; Kelkar 1965; Meegaskumbura 1980; Saint-Georges et al 2013)
baby talk a human universal? It depends on how you define “universal."
Infant-directed speech isn’t practiced everywhere. Parents who are
depressed or self-conscious aren’t so good at ID speech (e.g., Kaplan et
al 2007). And some parents may be discouraged by cultural attitudes.
instance, anthropologists have reported that the Kaluli of New Guinea
don’t engage their babies in conversation (Sheiffelin and Ochs 1996).
It’s also been reported that the Quiché Mayan speak to their babies in
the same pitch that they address adults (Ratner and Pye 1984).
these cases are exceptions to the rule. Yes, infant-directed speech is
subject to individual differences and cultural influences. But you can
say the same thing about most human behavior—including other parenting
practices, like breastfeeding.
So some researchers are
comfortable characterizing infant-directed speech as a human universal.
Indeed, researchers like Anne Fernald and Mary Monnot have argued that
baby talk is an evolved, species-specific adaptation (Fernald 1992;
According to this idea, infant-directed speech
evolved to facilitate baby communication. It's a tutorial style of
speech, one designed to help babies learn language, forge stronger
emotional attachments, and develop better social skills.
It’s an intriguing view--especially if you consider these findings.
Baby talk is an attention-grabber
Experimental research has shown that babies’ brains pay more attention to infant-directed speech.
one study of 3-month old infants, researchers played back recordings of
adult voices to sleeping babies. In some trials, babies heard
infant-directed speech. In other trials, they heard adult-directed
speech. When sleeping babies listened to the baby talk, they
experienced an increased blood flow to the frontal area of their brains
(Saito et al 2006).
Similarly, cognitive neuroscientists have
measured event-related potentials, or ERPs, in 6- and 13-month old
babies as they listened to both infant-directed and adult-directed
speech. The babies’ brains experienced more electrical activity when
they listened to baby talk (Zaigl and Mills 2007).
Why does baby talk grab the attention?
It might be the higher pitch.
Experiments have shown that infants listen longer to songs when they are sung in a higher pitch (Trainor and Zacharias 1998).
And high-pitched vocalizations are used as attention-getters among a
variety of species. For example, macaques use high-pitched calls to get
the attention of other group members (Koda and Masataka 2003).
is also evidence that human mothers modulate their pitch according to
their babies' levels of attentiveness. In a Japanese study, mothers
spoke with lower-pitched voices when their babies were vocally
responsive (Niwano and Sugai 2003). But when babies were more reticent,
moms raised the pitch.
Infant-directed speech might command attention for other reasons, too, such as the greater pitch range and more exaggerated emotional tone.
This seems possible because
- babies like it when men use infant-directed speech, even though male
voices don’t reach the same heights of pitch than women’s voices do
(Werker and McLeod 1989),
babies like to listen to adult-directed speech when it is highly-charged with pleasant emotion (Singh et al 2002), and
- when adult-directed speech is highly emotional, it takes on many of the
characteristics of baby communication. This includes a higher pitch,
but it also includes a greater pitch range and slower tempo (Trainor et
Baby talk makes emotions—and intentions—more obvious
Cultures vary widely in the amount of emotion that is conveyed in
speech. But within a given culture, infant-directed speech is more
demonstrative and emotional.
Does this make the intentions of a baby talker more obvious?
seems likely. After all, some Americans speak to their pets in a
sing-song, emotionally-exaggerated way (Mitchell 2001; Burnam et al
2002). Your dog might not understand the words, but he does understand
So we shouldn’t be surprised if members of our own
species have an easier time interpreting the emotions of infant-directed
In an interesting cross-cultural experiment, researchers
played back recordings of American English-speaking mothers to adults
of the Shuar, an indigenous South American group that practices hunting
and horticulture (Bryant and Barrett 2007).
The Shuar adults could
reliably identify which utterances were baby talk. And, despite no
knowledge of English, adult listeners were able to classify the
speakers’ intentions into four categories--prohibition, approval,
comfort, or attention.
They could do this when the English-speaking utterances were adult-directed.
But they performed even better when the utterances were baby talk.
Do babies pick up on the emotional cues of infant-directed speech?
Experiments suggests that they can.
one study, Stanford University researcher Anne Fernald and colleagues
presented 5-month old American babies with speech they had never heard
before: Vocalizations of approval and prohibition spoken in German,
Italian, and Japanese.
Then researchers noted the babies’ affective responses to each vocalization.
team found that the American babies listened with neutral affect to the
Japanese utterances—perhaps because Japanese moms don’t use as wide a
pitch range in their infant-directed speech (Fernald et al 1989).
when it came to the German and Italian utterances, the babies responded
with the appropriate emotion to each one-—positively to approvals and
negatively to prohibitions.
However, this was true only
when the babies had been presented with infant-directed speech. When
the messages of approval or prohibition took the form of adult-directed
speech, infants did not distinguish between them.
similar experiment was performed on Canadian babies listening to
utterances in a non-native language. In this case, 4- to 9-month old
babies watched a videotape of a woman speaking Cantonese. When the
woman's intention was baby communication, infants were more likely to
respond with pleasant emotions (Werker et al 1994).
Is baby talk designed to help babies learn speech?
We’ve seen how infant-directed speech might help babies pay closer
attention. It might also help babies “read" the emotions and intentions
But what about learning to speak?
Experiments suggest that infant-directed speech helps infants develop several key speech perception skills, including
- the ability to discriminate between different speech sounds
- the ability to detect the boundaries between words in a stream of speech
- the ability to recognize distinct clauses in a stream of speech
- the ability to "read lips," or match visual cues to their corresponding speech sounds
And infant-directed speech may help adults, too.
experiments conducted by Roberta Golinkoff and Anthony Alioto,
English-speaking adults found it easier to learn new Chinese words when
the words were spoken in the baby talk register (Golinkoff and Alioto
Does this imply that infant-directed speech is a kind of
“tutorial" mode of baby communication? It seems to. In fact, there is
even evidence suggesting that babies learn speech faster when their
parents use particularly expressive forms of infant-directed speech.
For more details, see this article about
language learning, baby communication, and infant-directed speech.
Other forms of baby communication
Speech isn't the only way that parents can talk with babies. As deaf
parents know, babies are also receptive to learning sign language. Even
babies of hearing parents may benefit from using gestures during speech.
For more information, see this article on the
science of baby signs.
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Photo credits for "Baby Communication":
image of father and baby ©iStockphoto.com/daniel rodriguez
image of Indian family by Ken Hammond
image mother & infant ©iStockphoto.com/Rohit Seth
Content of "Baby Communication" last modified 2/14