Language Development &
Perception Laboratories
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The language development laboratory focuses on how infants acquire spoken languge, and how their perception of language changes with development. Below we have descriptions of some of our recent research projects.
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| Infant listening in noise |
| One of the first tasks facing an infant is learning his or her native language. This is a difficult enough task in a quiet learning environment; yet infants often are exposed to speech in noisy environments. For example, a caregiver may be talking to an infant while other siblings are playing in the next room. In order to learn speech in these settings, the infant must first separate that speech from background noise such as that provided by TV shows and siblings. How do infants acquire their native language in such settings? |
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Toddlers' use of prior knowledge
As adults, we often listen to speech in situations that are not perfectly quiet. Other talkers, machine noises, even biological noises such as coughs and stomach gurgles can mask a talker's speech temporarily. Yet even when an outside noise covers up part of the incoming speech signal, we generally have little difficulty interpreting the intended message. Our prior knowledge of the language allows us to determine what the speaker intended to produce, even when part of the perceptual information is blocked.
Listening to speech in noise can also be a problem for young children - but they also do not have the same background knowledge that adults have, so they may not be able to rely on context to help them figure out intended meanings. Thus, toddlers may be faced with an even greater difficulty in listening to language than are adults, at a time when they are simultaneously trying to learn the language. Our lab has been exploring when children begin to use their developing pool of knowledge to aid in their interpretations. We have found that while 5-year-olds do make use of prior knowledge, toddlers (aged 24-30 months) appear not to use prior knowledge to "fill in the gaps" in their perception. Instead, they appear to be more tied to the acoustic information they receive, and require more of the signal to be intact in order to properly identify it.
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The role of segmentation in later language development
A growing body of literature has theorized about the processing skills infants might need to begin acquiring language. One critical skill that infants need to acquire is the ability to separate (or "segment") fluent speech into individual words. This is a necessary skill because most of the speech that infants hear is made up of fluent sentences, and infants must determine where a word begins and ends before they can learn it. Prior work has found that children typically show the ability to segment words by approximately 7.5 months of age. Yet some infants at this age do not demonstrate this same ability. We have been exploring the relationship between how infants perform in a laboratory setting (between 6 & 12 months of age) and their later language outcomes. We found that children who failed to show evidence of segmentation skills as infants had poorer grammatical and vocabulary scores even years later (at 4-6 years of age). These results demonstrate the importance of segmentation ability for successful language development, but they also offer the potential for developing measures to detect language impairment at a far earlier age.
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Word Finding in Children
Everyone occasionally has problems finding a word that they know. For children, this happens even more often than for adults. We have been exploring properties of words that might make them easier or harder for children to find, or access. These factors can tell us about how children's "mental dictionaries" are organized. We have also been comparing different groups of children, examining both children who are developing typically, and those who have been diagnosed with learning disabilities, to help identify the underlying causes of differences between these groups. In addition to looking at children with learning disabilities, we have also been examining lexical access in children who stutter, since one possibility is that these children have subtle deficits in their ability to find words.
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Infants' Working Memory
How many things in a row can an infant remember? In order to successfully learn language, infants must be able to store information about what they are hearing. We are exploring the limits of one type of memory, working memory. This is the type of memory that allows individuals to hold things in mind long enough to work on them. We are just beginning this line of work, trying to determine how many items infants can hold in memory, and how this skill changes with development.
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Children's comprehension of plurals
People have long been amazed by young children¹s rapid acquisition of new words. By some accounts. children produce over 500 different words by the time they reach their second birthday, and comprehend thousands more. This has led to a large literature, examining how children learn words. But there has been far fewer studies of how children learn other aspects of their language, such as the grammatical markers. We have been exploring the ages at which children first begin to understand the concept of plurals, that the "s" at the end of an utterance means "more than one". So far, it seems as if children first begin to recognize the plural marker only for particular words they know well; they don't learn the more general rule until they approach 2 years of age.
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This material is based in part upon work supported by the National Science
Foundation and the National Institutes of Health. Any opinions, findings,
and conclusions or recommendations expressed in this material are those of
the author(s) and do not necessarily reflect the views of the National
Science Foundation or the National Institutes of Health. |
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