Mental Retardation & Language Aylin Küntay Language and Communicative Disorders Meeting 13

Kanaya & Ceci (Child Development Perspective, Vol. 1, 2007) The IQ cutoff score of 70 is used for the diagnosis of MR in the US Give educational help to those below 2 standard deviations below the mean of 100 Represents the bottom 2.27% of the population Problems associated with this cutoff

Problems The Flynn effect: as IQ test norms get older, people perform better on them, raising the mean IQ by several points within a matter of years Because of environmental changes such as advancements in technology, schooling, and nutrition The MR cutoff score of 70 captures a smaller percentage of the population with every passing year IQ tests need to be renormed every 10 or 20 years

Chapman: Lang Dev in DS, Pragmatics Less initiation of communication But mothers respond more Lack of intelligibilty does not limit communicative attempts Rates of linguistic imitation lower than MA controls Imitated utterances less complex than spontaneous utterances Limitions of auditory STM

Phonological development Delayed onset of canonical babbling Show examples from typical But still show babbling; relatively independent of MA More phonological errors at school-age than TD Final consonant deletion, cluster reduction, fronting persist in adolescence Reduced intelligibility

Lexical dev Spoken vocabulary emerges at roughly the same mental ages in children with DS as in TD children Early vocabularies accumulate slowlier in DS compared to mental age controls Rate, but not onset, of vocabulary acquisition is slower Current education practice emphasizes signing The spoken vocabulary gap decreases Might be due to phonological issues

Hearing Children with DS have a high prevalence of mild to moderate hearing loss associated with otitis media (middle ear infection) Thus some delays could be due to hearing loss

Syntax dev Problems in expressive syntax in free speech samples Onset of multiword combinations occur at similar mental ages to TD But DS shows increasing divergence of MLU from the mental-age matched controls By age 21 months, the two groups differ significantly Aspects of expressive lang dev stop or plateau in children with DS Delayed language without deviance Chapman found counterevidence to plateau Narratives of adolescents with DS aged 16-20 years show more syntactic complexity than narratives of 5-16 years

Language comprehension Problems in speech perception Problems in forming complex auditory representations Comprehension vocabulary is an area of potential strength No deficit in onset or acquisition of comprehension vocabulary Fast mapping paradigm Remembers the nonsense object given a simple novel label in a game As good as nonverbal MA controls

Syntax comprehension Syntax comprehension similar to MA-controls in childhood; lags behind in adolescence Word order comprehension: relies on semantic plausibility, not syntactic cues School aged children with DS show less verb-based interpretations in interpreting Noah’s Ark “act-out” sentences The zebra goes the lion Also needed to repeat the sentences more DS often forgot the test sentence by the time they search for the objects

Reading Develop reading skills when given the educational opportunity Wide variation

Summary Normal development of comprehension relative to MA in the first 5 years of life Emergence of a production deficit increasing in probability with mental age Chronological age and levels of nonverbal cognitive dev are predictors of levels of language dev To a lesser extent, hearing status affects intelligibilty of speech

Kids With Down Syndrome Learn Language Beyond Adolescence http://www Chapman and her colleagues have charted the trajectory of learning skills and memory abilities in 31 individuals with Down syndrome who were ages 5-20 at the study's start. Through comprehension tests and storytelling tasks, they measured each person's ability to understand complex grammar (language comprehension) and his or her ability to speak it (language expression). While Chapman found that some language skills may stop developing as these children reach late adolescence, she also found that language expression skills continue to improve well into young adulthood - and that their development depends on the development of language comprehension skills, which do tend to plateau.

Kids With Down Syndrome Learn Language Beyond Adolescence http://www Chapman found, however, that the continued development of language expression depends on at least maintaining comprehension skills. "The rate of change in expressive learning skills," she says, "is predicted by the rate of change in language comprehension skills." For example, if an adolescent acquires the ability to understand complex grammar more slowly, he will also acquire the ability to speak that grammar more slowly. These findings, says Chapman, point to the importance of continuing language intervention during the teen-age years: "The study's findings suggest that there should continue to be language work in both comprehension and expression throughout teen-age and young adult years."

Auditory short memory as a source of individual variation Sequential processing deficit? Global order errors? Not really Auditory processing deficit? Better performance in visual short-term memory tasks than auditory tasks Visual vs. auditory sequencing Remembering and repeating digits; familiar word string; letter names; sentences Correlation btw auditory STM and sentence imitation Slower identification of incoming items Interventions focus on visual representations Signing, reading, writing