Wednesday, December 19, 2012
Devescovi, A., & Caselli, M.C. (2007). Sentence repetition as a measure of early grammatical development in Italian. International Journal of Language & Communication Disorders, 42(2), 187–208.
Early identification of language impairment is essential in order to provide timely intervention, however, few standardized measures exist for children under four years of age. Devescovi and Caselli suggest that the Sentence Repetition Test (SRT) could serve as a suitable assessment of language development for young children based on the premise that a child’s ability to repeat a sentence is representative of her spontaneous language abilities. Consensus has not been reached on whether the SRT is an accurate measure of language ability; some say it overestimates ability, while others argue it underestimates it. Most significantly though, SRT has been recognized as a tool for identifying language impairment (e.g., Conti-Ramsden et al., 2001).
In the first of two studies, Devescovi and Caselli examine test-retest reliability of SRT in 100 Italian-speaking children aged 2;0 to 4;0. The authors find that calculating the mean length of utterance in words is sensitive to linguistic development between the ages of 2;0 and 2;6, and that number of sentences repeatedly correctly better discriminates the older age bands. It is important to note that MLU is calculated in words in this study by counting not morphemes, but whole words, which is common in studies of the development of Italian. Perhaps calculation of MLU using morphemes would offer better discrimination beyond 2;6.
In the second study, Devescovi and Caselli examine the correlation between SRT performance, verbal memory span (VMS), and spontaneous speech (structured conversation and picture description), noting that verbal memory span has been shown to predict MLU in spontaneous speech (Blake et al., 1994). SRT responses and spontaneous utterances are analyzed for three factors: number of verbs, omitted articles, and MLU (in words). Analysis revealed no correlation between any of these measures and VMS after controlling for age. Article omission and number of verbs in SRT were both related to spontaneous speech, while correlation between MLU (in words) of SRT and spontaneous speech was not significant.
The sentences used in the SRT included simple sentence structure and only those morphemes expected to develop by 4;0. While it is important to include sentences that could be repeated by the youngest children in the age span, it is possible that limiting the complexity of the stimuli may have limited the performance of the older children, causing a ceiling effect. Despite limitations of the task, positive correlations shown in the findings suggest that some form of SRT may be beneficial in assessing language of young children.
Blogger: Laura Pauls
Variability and Detection of Invariant Structure. Gomez, R. L. (2002). Psychological Science, 13, 5.
Recent theories of language learning suggest that language learners are particularly adept at tracking the statistical regularities that exist within natural language. For example, learners are able to sensitive to “adjacent dependencies”, that is, the higher probabilities that occur between adjacent syllables within words than between words. However, a key aspect of language learning involves learning patterns between “non-adjacent dependencies”. Some examples of nonadjacent dependencies experienced in everyday language use are the dependencies between auxiliaries and inflectional morphemes (e.g.: is running), and dependencies involving agreement (e.g.: the kids in the park are playing). What is of interest to researchers is how humans learn to track these nonadjacent relationships.
In an experimental task involving learning nonadjacent dependencies, subjects listen to a string of syllables and must learn that a particular non-adjacent pattern – for example, that a first element always occurs with a third element in the string. A key hypothesis in this learning regards the middle element. If the middle element varies more, the pattern between the first and third element becomes more salient and the learner shows greats sensitivity to learning the nonadjacent dependency.
In this study, adults and infants were exposed to an artificial language containing nonadjacent dependencies between words (e.g.: aXd, bXe, cXf). The set size of X varied between conditions, drawing X from a set size of either 2, 6, 12, or 24 elements. Learning was greater for when the set size from which X was drawn was highly variable (set size = 24). These results demonstrate that learning is adaptable may be dynamically guided by the statistical structure in their linguistic environment. It should be noted that these results have not been replicated in all subsequent studies.
Statistical learning in children with language impairment has been investigated only recently (see blogpost from Evans et al., 2009). It may be that these children have more difficulty recognizing such patterns in language. Current interventions involving explicitly teaching linguistic rules may facilitate this learning.
Blogger: Nicolette Noonan
Monday, December 10, 2012
Relationships Among Linguistic Processing Speed, Phonological Working Memory, and Attention in Children Who Stutter
Anderson, J. D., & Wagovich, S. A. (2010). Relationships among linguistic processing speed, phonological working memory, and attention in children who stutter. Journal of Fluency Disorders, 35, 216-234.
Studies of speech reaction time (SRT) are thought to examine the efficiency with which a person processes and responds to language-based stimuli. The few studies that have examined SRT in groups of children who stutter (CWS) and their typically developing peers have revealed mixed findings.
One finding is that longer SRT’s correspond with higher receptive vocabulary scores in children who do not stutter, but that for CWS, there appears to be no relationship between vocabulary and SRT. It is proposed that the relationship between vocabulary scores and SRT’s in typically fluent groups is mediated by lexical competition, such that individuals with larger vocabularies take longer to select a word and thus have slower reaction times than children with poorer vocabularies. Anderson and Wagovich hypothesized that factors related to lexical processing, such as phonological working memory, may correlate with SRT’s in children who stutter. These researchers also investigated whether attentional processes may affect SRT’s in CWS.
In this study, groups of children who do or do not stutter completed nonword repetition, picture naming, and their parents completed a temperament questionnaire about them. These measures were used to evaluate phonological working memory, SRT, and attention, respectively. Results revealed that performance on tests of nonword repletion related to SRT in the children who stuttered but not the typically fluent group. Anderson and Wagovich concluded that for CWS, phonological working memory is associated with SRT.
Nonword repetition is typically considered to be a measure of phonological short-term memory because it involves immediate repetition only, rather than additionally requiring information processing as in working memory tasks. More broadly, nonword repetition taps several processes involved in phonological processing (discrimination, encoding, storage, output). Further work is needed to understand what underlying process may account for the associations between nonword repetition and SRT in the CWS in this study.
Blogger: Alexandra Smith