Toddlers are surprisingly good at processing the speech of other young children, according to a new study.
And toddlers who have more exposure to other children, such as those in daycare, may be particularly good at certain word learning skills.
Researchers at the University of Waterloo examined the word processing skills of toddlers who spend most of their time with adults compared with those who have more exposure to groups of children.
They focused on how well the toddlers understood the speech of other children.
Although all of the toddlers were very good at processing child speech, the study found that toddlers who had more exposure to other children were better at associating a new word to a new object, an important part of word learning.
Child speech differs from adult speech in many ways.
Even a child who is six or seven years old pronounces words a bit differently than adults.
“We wanted to know if more exposure hearing other children speak would affect toddlers‘ ability to process child speech,” said Katherine White, professor of psychology at Waterloo, who co-authored the study with Ph.D. candidate, Dana Bernier.
In the study, the researchers conducted two experiments with a total of 88 toddlers (and their parents), some of whom spent eight hours or less per week with other children, and others who had more weekly experience in child groups.
Experiment 1 compared their processing of instructions from a seven-year-old child speaker and from an adult speaker pronouncing a familiar or novel object’s name in the standard way.
Experiment 2 tested the sensitivity of the toddlers’ speech processing by having the child speaker mispronounce the object names.
“Our study demonstrates that toddlers are extremely good at processing the speech of young children, and that this is true even for toddlers who do not have a lot of experience with other children.
This means that they could use this kind of speech, in addition to adult speech, to learn about their native language(s),” said White.
“However, we also found an intriguing difference in how toddlers processed new words that was related to how much exposure they had to other children.”
“Most studies focus on how toddlers learn from adult speakers. But we think it’s important to explore how toddlers process the speech of children of various ages and how much they use speech from other children to guide their language learning,” said White.
The study, Toddlers’ sensitivity to phonetic detail in child speech, by Dana Bernier and Katherine White, appears in the Journal of Experimental Child Psychology.
At any given age, there is wide variability among children in their levels of language proficiency (Fenson et al., 1994).
Although differences in verbal abilities among individuals are influenced to some extent by genetic factors (Oliver & Plomin, 2007), the contributions of early experience to such differences are also substantial.
Factors associated with socioeconomic status (SES) are strongly associated with variation in language outcomes.
By the time they enter kindergarten, children from disadvantaged backgrounds differ significantly from their more advantaged peers in verbal and other cognitive abilities (Ramey & Ramey, 2004), disparities that are predictive of later academic success or failure (Hart & Risley, 1995; Lee & Burkam, 2002).
Identifying the environmental factors that shape these consequential differences in early language proficiency is critical for remediating the growing achievement gaps between children from impoverished and affluent families (Duncan & Murnane, 2011).
What accounts for differences among children in their early language growth?
One source of variability in rates of language learning is differential access to language and gesture from caregivers.
Some parents talk more and use richer vocabulary and gesture in interactions with infants than do others, and such differences in the quantity and quality of language input account in part for later disparities among children in lexical and grammatical development, both within and between socio-economic groups (Hart & Risley, 1995; Hoff, 2003a; Huttenlocher, Waterfall, Vasilyeva, Vevea, & Hedges, 2010; Pan, Rowe, Singer, & Snow, 2005; Rowe & Goldin-Meadow, 2009).
A second source of variability in language learning relates to infants’ speech processing skills.
Differences among infants in phonological discrimination (Tsao, Liu, & Kuhl, 2004) and spoken word recognition (Fernald, Perfors, & Marchman, 2006; Singh, Steven Reznick, & Xuehua, 2012) predict early vocabulary growth.
In experimental studies in which infants look at pictures of familiar objects as one object is named, their speed and accuracy in recognizing the object name and identifying the correct picture in real time predicts both early vocabulary development and later language and cognitive skills (Fernald & Marchman, 2011; Fernald et al., 2006; Marchman & Fernald, 2008).
These studies show that children’s language outcomes are linked both to early experience with language and to speech processing skills in infancy, but it is not well understood how these two influences work together over development to promote vocabulary growth.
Here we investigate two alternative possibilities:
One is that language experience and language-processing skill are separate factors that contribute independently to lexical development.
That is, variation in children’s vocabulary growth could result from differences in children’s exposure to speech – and thus in their opportunities to learn new words – or from pre-existing differences in children’s ability to process speech efficiently, with some children better able to take advantage of the learning opportunities available to them.
Another possibility is that early experience with language actually influences the development of efficiency in real-time language processing.
That is, experience in hearing language from caregivers may sharpen infants’ skill in processing speech, and hence improve their ability to learn from future language input.
A recent study comparing infants from higher- and lower-SES families found that significant disparities in language processing efficiency were already present by 18 months of age (Fernald, Marchman, & Weisleder, 2013), suggesting that experiential factors associated with SES may contribute to differences in processing skill.
In addition, one previous study showed that infants exposed to richer language input were more efficient in language processing (Hurtado, Marchman, & Fernald, 2008).
However, in this study the relation between language experience and processing efficiency could be explained by children’s vocabulary size.
To address this gap, we ask here: Is early experience with language linked to the development of efficiency in language processing?
And if so, do differences in processing efficiency mediate the well-established relation between early language experience and later vocabulary knowledge? Answers to these questions will help us understand the developmental pathways linking early language experience, speech-processing efficiency and vocabulary growth.
More information: Dana E. Bernier et al. Toddlers’ sensitivity to phonetic detail in child speech, Journal of Experimental Child Psychology (2019). DOI: 10.1016/j.jecp.2019.04.021
Journal information: Journal of Experimental Child Psychology
Provided by University of Waterloo