'Parentese' helps parents, babies make 'conversation' and boosts language development

Mother talking to baby (stock image).

Used in virtually all of the world's languages, parentese is a speaking style that draws baby's attention. Parents adopt its simple grammar and words, plus its exaggerated sounds, almost without thinking about it.

But if parents knew the way they speak could help baby learn, would they alter their speech?

A new study from the Institute for Learning & Brain Sciences, or I-LABS, at the University of Washington suggests they would, to baby's benefit. Researchers examined how parent coaching about the value of parentese affected adults' use of it with their own infants, and demonstrated that increases in the use of parentese enhanced children's later language skills.

The study, published online Feb. 3 in the Proceedings of the National Academy of Sciences, finds that parents who participated in individual coaching sessions used parentese more often than control-group parents who were not coached, and that coaching produced more parent-child "conversational turns" and increased the child's language skills months later.

"We've known for some time that the use of parentese is associated with improved language outcomes," said Patricia Kuhl, I-LABS co-director and professor of speech and hearing sciences at the UW. "But we didn't know why. We believe parentese makes language learning easier because of its simpler linguistic structure and exaggerated sounds. But this new work suggests a more fundamental reason.

"We now think parentese works because it's a social hook for the baby brain -- its high pitch and slower tempo are socially engaging and invite the baby to respond."

Parentese is not what is often called "baby talk," which is generally a mash-up of silly sounds and nonsense words. Instead, it is fully grammatical speech that involves real words, elongated vowels and exaggerated tones of voice. Spoken directly to the child, it sounds happy and engaged, and helps infants tune in socially to their parents and respond, even if only through babbling.

In a 2018 study, I-LABS researchers tracked use of parentese among adults and their 6-month-old infants, and found that babies whose parents participated in parentese coaching sessions babbled more and produced more words by age 14 months than infants whose parents were not directed in the technique.

The new study focuses on the long-term outcomes of parent coaching and how it led to changes in the parents' language, in parent-child conversation, and eventually, in the child's speech at 18 months.

"We had no idea that parents would respond so positively to information about how their own speech to the child affects the child's language development. Parent coaching gave parents a measurement tool, almost like a Fitbit for parentese, and it worked," said lead author Naja Ferjan Ramírez, a UW assistant professor of linguistics.

To assess child language output, all families in the study were given a lightweight recorder, which the child wore in a specially designed vest during four separate weekends at ages 6, 10, 14 and 18 months. The device recorded both parent and infant speech over the entirety of two consecutive days, so that researchers could measure parents' use of parentese, parent-child conversational turns, as well as infant language production -- either babbling or actual words. Parent coaching sessions occurred at 6, 10 and 14 months.

For the 48 families randomly assigned to receive coaching, the sessions provided guidance and feedback on specific communication strategies, such as using parentese, speaking directly to the child and engaging the child in back-and-forth exchanges known as conversational turns. In reviewing recordings with parents, researchers played back recordings of parents' language behaviors and measured them against research-based targets for child language development. Parents were encouraged to include language as part of daily routines and were given language-interaction tips in the form of cards with "brain building" tips from Vroom, a program of the Bezos Family Foundation.

All parents in the study already used parentese at the beginning of the project, but their use varied greatly, the researchers said. Those in the coaching group learned more about the cognitive and social benefits of parentese, when and how to use it to promote interaction with their child, and the positive effects that parentese could have on their child's language development.

The results show that parent coaching resulted in an increased use of parentese and infant vocalizations that continued to grow after the end of the parent coaching sessions. Between 14- and 18-months, coached families showed a drastic jump in conversational turn-taking and child vocalizations. Children of coached parents produced real words -- such as "banana" or "milk" -- at almost twice the frequency of children whose parents were in the control group. Parent surveys estimated that the children's 18-month vocabulary averaged around 100 words among children of coached families, compared to 60 words among children in the control group.

"We know that language skills in infancy predict subsequent stages in language development, so enhancements in language behaviors in infancy could therefore have cascading effects on speech development over time," said Ferjan Ramírez.

Kuhl added, "Language evolved to facilitate the social communication skills that are essential for survival of the species. In this study, we observe firsthand how parents' language and social engagement can promote baby's initial responsive coos, which become words, and then sentences -- educating infants in the art of human communication."

The study was funded by the Overdeck Family Foundation and UW I-LABS Ready Mind Project. Sarah Roseberry Lytle, outreach and education director at I-LABS, was a co-author.

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Materials provided by University of Washington. Original written by Kim Eckart. Note: Content may be edited for style and length.

Babies in the womb may see more than we thought

Illustration of fetus inside womb

By the second trimester, long before a baby's eyes can see images, they can detect light.

But the light-sensitive cells in the developing retina -- the thin sheet of brain-like tissue at the back of the eye -- were thought to be simple on-off switches, presumably there to set up the 24-hour, day-night rhythms parents hope their baby will follow.

University of California, Berkeley, scientists have now found evidence that these simple cells actually talk to one another as part of an interconnected network that gives the retina more light sensitivity than once thought, and that may enhance the influence of light on behavior and brain development in unsuspected ways.

In the developing eye, perhaps 3% of ganglion cells -- the cells in the retina that send messages through the optic nerve into the brain -- are sensitive to light and, to date, researchers have found about six different subtypes that communicate with various places in the brain. Some talk to the suprachiasmatic nucleus to tune our internal clock to the day-night cycle. Others send signals to the area that makes our pupils constrict in bright light.

But others connect to surprising areas: the perihabenula, which regulates mood, and the amygdala, which deals with emotions.

In mice and monkeys, recent evidence suggests that these ganglion cells also talk with one another through electrical connections called gap junctions, implying much more complexity in immature rodent and primate eyes than imagined.

"Given the variety of these ganglion cells and that they project to many different parts of the brain, it makes me wonder whether they play a role in how the retina connects up to the brain," said Marla Feller, a UC Berkeley professor of molecular and cell biology and senior author of a paper that appeared this month in the journal Current Biology. "Maybe not for visual circuits, but for non-vision behaviors. Not only the pupillary light reflex and circadian rhythms, but possibly explaining problems like light-induced migraines, or why light therapy works for depression."

Parallel systems in developing retina

The cells, called intrinsically photosensitive retinal ganglion cells (ipRGCs), were discovered only 10 years ago, surprising those like Feller who had been studying the developing retina for nearly 20 years. She played a major role, along with her mentor, Carla Shatz of Stanford University, in showing that spontaneous electrical activity in the eye during development -- so-called retinal waves -- is critical for setting up the correct brain networks to process images later on.

Hence her interest in the ipRGCs that seemed to function in parallel with spontaneous retinal waves in the developing retina.

"We thought they (mouse pups and the human fetus) were blind at this point in development," said Feller, the Paul Licht Distinguished Professor in Biological Sciences and a member of UC Berkeley's Helen Wills Neuroscience Institute. "We thought that the ganglion cells were there in the developing eye, that they are connected to the brain, but that they were not really connected to much of the rest of the retina, at that point. Now, it turns out they are connected to each other, which was a surprising thing."

UC Berkeley graduate student Franklin Caval-Holme combined two-photon calcium imaging, whole-cell electrical recording, pharmacology and anatomical techniques to show that the six types of ipRGCs in the newborn mouse retina link up electrically, via gap junctions, to form a retinal network that the researchers found not only detects light, but responds to the intensity of the light, which can vary nearly a billionfold.

Gap junction circuits were critical for light sensitivity in some ipRGC subtypes, but not others, providing a potential avenue to determine which ipRGC subtypes provide the signal for specific non-visual behaviors that light evokes.

"Aversion to light, which pups develop very early, is intensity-dependent," suggesting that these neural circuits could be involved in light-aversion behavior, Caval-Holme said. "We don't know which of these ipRGC subtypes in the neonatal retina actually contributes to the behavior, so it will be very interesting to see what role all these different subtypes have."

The researchers also found evidence that the circuit tunes itself in a way that could adapt to the intensity of light, which probably has an important role in development, Feller said.

"In the past, people demonstrated that these light-sensitive cells are important for things like the development of the blood vessels in the retina and light entrainment of circadian rhythms, but those were kind of a light on/light off response, where you need some light or no light," she said. "This seems to argue that they are actually trying to code for many different intensities of light, encoding much more information than people had previously thought."

The research was supported by the National Institutes of Health (NIH F31EY028022-03, RO1EY019498, RO1EY013528, P30EY003176).

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Story Source:

Materials provided by University of California - Berkeley. Original written by Robert Sanders. Note: Content may be edited for style and length.