Wednesday, October 24, 2012

Grammatical Difficulties in Children with SLI: Is Learning Deficient?

Grammatical Difficulties in Children with SLI: Is Learning Deficient? Hsu, H. J., & Bishop, D. (2011). Hum Dev. 53(5): 264-277.

One view of language learning suggests that children (and humans generally) are sensitive to the patterns of sounds that they hear in language. This statistical learning is based on the frequencies or probabilities of sounds in the language. First, young children store heard sentences in an exemplar-by-exemplar fashion (Ellis, 2002), memorizing individual items. In time, children develop more  abstract (syntactic) patterns of different types, and these frames allow them to produce correct grammatical sentences (Ellis, 2002).

Hsu and Bishop discuss the viewpoint that the grammatical deficits in SLI are due to an impairment in the ability to extract these statistical patterns from the input. As a result, children with SLI may require more exposure to learn abstract syntactic patterns. Indeed, Bishop, Adams, and Rosen (2006) found that even after daily training with a particular construction type, children with SLI did not achieve fluent automatic comprehension. It may be that the poor statistical learning in SLI results from other deficits, however. Limitations in short-term memory (Coady & Evans, 2008) or speech perception (Joanisse et al., 2000) may negatively impact statistical learning abilities in SLI.

Children with SLI may have difficulty identifying patterns in the language they hear. Isolating particular patterns to increase the frequency of exposure and highlight the form are approaches that would be consistent with this viewpoint.

Blogger: Areej Balilah. 

Wednesday, October 17, 2012

Cognitive Profiling and Preliminary Subtyping in Chinese Developmental Dyslexia

Ho, C. S. H., Chan, D. W. O., Lee, S. H., Tsang, S. M., & Luan, V. H. (2004). Cognition, 91, 43-75.

Even though reading impairment is thought to be just as common among children in China as it is in other countries, most of the pioneering research on dyslexia has been conducted in English with the English alphabet. As a result, the leading theories of dyslexia account for reading impairment in languages like English, but it is unclear whether they apply to languages like Chinese with logographic written symbols. According to one theory called the phonological deficit hypothesis, children with reading impairment may have difficulty mapping (or matching) print and sound due to noisy representations of words in their brains (or underspecified phonological representations).

Ho and colleagues suggest that in Chinese, the nature of the deficits underlying dyslexia might be different. This is because of the nature of Chinese script, as parts of the written symbols in Chinese don’t directly map onto sounds in the word in the same way they do in English. The authors tested 147 Cantonese-speaking children with dyslexia in Hong Kong. Measures included the ability to rapidly name pictures (rapid naming), manipulate sounds in words (phonological processing), read symbols (orthographic processing), and other visual-perceptual skills. Ho and colleagues found that more children had problems with rapid naming (57% of children) and orthographic processing (42%) than with phonological processing (29%) and visual processing (27%). In other analyses involving step-wise regression, results suggested that rapid naming and orthographic processing are related to reading impairment in Chinese. Unlike findings for English speakers, phonological processing was not importantly related to dyslexia in Chinese. These results have implications for the types of intervention strategies that might be used to help children in China improve their reading.

A final note: it is worth mentioning that the phonological processing tasks used in this study were rather simple, and children performed very well on them (even those classified with reading impairment). These tasks asked children to indicate which of two syllables out of a group of three shared sounds. It might be that phonology would have been found to play a larger role in Chinese dyslexia if other tasks had been included. This remains an ongoing debate.

Guest blogger: Jeff Malins from the Language, Reading and Cognitive Neuroscience Lab. Jeff is a PhD student in Neuroscience, and has used measures such as eyetracking, ERPs, and fMRI to study spoken word recognition in adult native speakers of Mandarin Chinese. He is also currently collaborating with researchers in Beijing on a project looking at Mandarin spoken word recognition in children with reading impairments