Genetic and environmental factors that influence language development
While the vast majority of children learn to communicate through language effortlessly, as many as 15 percent of them struggle with the process. Even within the majority, there are wide variations in the way the process unfolds. I believe that understanding the causes of language learning differences will lead to more effective interventions and preventions. I am currently involved in a longitudinal study of twins in kindergarten through fifth grade funded by the National Institute of Child Health and Human Development. The study has provided evidence of both genetic influences and what I call non-shared environmental influences, such as differences in friends, exposures to toxins, and so on. The next step will be to tease out the specific genetic and environmental factors that influence language development. I believe these factors may have more impact on language development than the family-level variables that are traditionally deemed important, such as the specific way or length of time that parents interact with their children. In addition to the twin study, I am engaged in research focused on treatment of speech-language disability associated with autism and apraxia of speech. I am collaborating with scholars from computer science and special education to determine whether a computer-based visual feedback tool is more, less, or equally effective as the pacing boards that are now used to cue children who have trouble producing more than one syllable at a time. I feel it is critical to provide speech-language pathologists with evidence that guides their treatment decisions, thereby making a critical contribution to evidence-based practices in health sciences. I also would like to broaden the field’s measures of success, moving away from specific speech sounds and grammatical structures and toward how well the child communicates in general, makes friends, and builds meaningful community.
DeThorne LS, and Watkins RV. 2006. Language abilities and nonverbal IQ in children with language impairment: Inconsistency across measures. Clinical Linguistics and Phonetics 20(9)641-658.
DeThorne LS, Hart SA, Petrill SA, Deater-Deckard K, Thompson LA, Schatschneider C, and Davison MD. 2006. Children's history of speech-language difficulties: Genetic influences and associations with reading. Journal of Speech, Language, and Hearing Research 49(6)1280-1293.
Petrill SA, Deater-Deckard K, Thompson LA, DeThorne LS, and Schatschneider C. 2006. Reading skills in early readers: Genetic and shared environmental effects. Journal of Learning Disabilities 39:48-55.
DeThorne LS, Petrill SA, Hayiou-Thomas E, and Plomin R. 2005. Low expressive vocabulary: Higher heritability as a function of more severe cases. Journal of Speech, Language, and Hearing Research 48:792-804.
DeThorne LS, Johnson BW, and Loeb JW. 2005. A closer look at MLU: What does it really measure? Clinical Linguistics and Phonetics 19:635-648.