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Abstract
<p class="first" id="P1">Young children’s language experiences and language outcomes
are highly variable. Research
in recent decades has focused on understanding the extent to which family socioeconomic
status (SES) relates to parents’ language input to their children and, subsequently,
children’s language learning. Here, we first review research demonstrating differences
in the quantity and quality of language that children hear across low-, mid-, and
high-SES groups, but also—and perhaps more importantly—research showing that differences
in input and learning also exist within SES groups. Second, in order to better understand
the defining features of ‘high-quality’ input, we highlight findings from laboratory
studies examining specific characteristics of the sounds, words, sentences, and social
contexts of child-directed speech (CDS) that influence children’s learning. Finally,
after narrowing in on these particular features of CDS, we broaden our discussion
by considering family and community factors that may constrain parents’ ability to
participate in high-quality interactions with their young children. A unification
of research on SES and CDS will facilitate a more complete understanding of the specific
means by which input shapes learning, as well as generate ideas for crafting policies
and programs designed to promote children’s language outcomes.
</p>
The poor often behave in less capable ways, which can further perpetuate poverty. We hypothesize that poverty directly impedes cognitive function and present two studies that test this hypothesis. First, we experimentally induced thoughts about finances and found that this reduces cognitive performance among poor but not in well-off participants. Second, we examined the cognitive function of farmers over the planting cycle. We found that the same farmer shows diminished cognitive performance before harvest, when poor, as compared with after harvest, when rich. This cannot be explained by differences in time available, nutrition, or work effort. Nor can it be explained with stress: Although farmers do show more stress before harvest, that does not account for diminished cognitive performance. Instead, it appears that poverty itself reduces cognitive capacity. We suggest that this is because poverty-related concerns consume mental resources, leaving less for other tasks. These data provide a previously unexamined perspective and help explain a spectrum of behaviors among the poor. We discuss some implications for poverty policy.
Infants differ substantially in their rates of language growth, and slow growth predicts later academic difficulties. In this study, we explored how the amount of speech directed to infants in Spanish-speaking families low in socioeconomic status influenced the development of children's skill in real-time language processing and vocabulary learning. All-day recordings of parent-infant interactions at home revealed striking variability among families in how much speech caregivers addressed to their child. Infants who experienced more child-directed speech became more efficient in processing familiar words in real time and had larger expressive vocabularies by the age of 24 months, although speech simply overheard by the child was unrelated to vocabulary outcomes. Mediation analyses showed that the effect of child-directed speech on expressive vocabulary was explained by infants' language-processing efficiency, which suggests that richer language experience strengthens processing skills that facilitate language growth.
It is widely accepted that infants begin learning their native language not by learning words, but by discovering features of the speech signal: consonants, vowels, and combinations of these sounds. Learning to understand words, as opposed to just perceiving their sounds, is said to come later, between 9 and 15 mo of age, when infants develop a capacity for interpreting others' goals and intentions. Here, we demonstrate that this consensus about the developmental sequence of human language learning is flawed: in fact, infants already know the meanings of several common words from the age of 6 mo onward. We presented 6- to 9-mo-old infants with sets of pictures to view while their parent named a picture in each set. Over this entire age range, infants directed their gaze to the named pictures, indicating their understanding of spoken words. Because the words were not trained in the laboratory, the results show that even young infants learn ordinary words through daily experience with language. This surprising accomplishment indicates that, contrary to prevailing beliefs, either infants can already grasp the referential intentions of adults at 6 mo or infants can learn words before this ability emerges. The precocious discovery of word meanings suggests a perspective in which learning vocabulary and learning the sound structure of spoken language go hand in hand as language acquisition begins.
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