1. Underlying cognitive skills in language impairment and dyslexia
Katherine Hall
Department of Psychology, University of Coventry, UK
Introduction:
Parmentier, & Barr, 2013; Smith-Spark, Fisk, & Nicholoson, 2003).
In LI deficits have been found in both verbal (DSB) (Marton, & Schwartz, 2003) and visual (N back task) tasks (Im-Bolter, Johnson, & Pascual – Leone, 2006)
Predictions and aims
Dyslexics suffer form a specific verbal short term memory problem which can lead to verbal working memory and executive problems (Reiter, Tucha & Lange, 2005).
L.I individuals suffer from a more general executive impairment (Im-Bolter, Johnson, & Pascual – Leone, 2006 ) which extends to verbal and visual inhibition and working memory domains (Henry, Messer, Nash, 2012).
The aim of the study therefore is to test both literacy and language impaired pupils in strictly verbal and visual tasks of both inhibition and working memory with the use of age and younger language / literacy ability matches to investigate this.
Participants:
Introduction:
Dyslexia
Specific learning disability (Rutter & Yule, 1975). Literacy ability discrepant to that expected for age, given avg. IQ, education level (1.5 – 2.5 SD).
Difficulties in the accurate and fluent decoding of words and speech sounds but not comprehension difficulty
Language impairment (LI)
Oral language skills lower (2 SD +) than expected given normal non-verbal IQ. Deficits in receptive (comprehension) and / or expressive (production) language skills. A deficit in at least 2 of 5 areas of language, vocabulary, grammar, narrative, expressive skills, receptive skills (Tomblin, Records & Zhang, 1996).
Modelling the overlap
Estimated 50% who meet criteria for dyslexia also meet the criteria for LI.
Bishop and Snowling (2004) propose both dyslexic and LI individuals will show a deficit in phonology but those with LI will also show deficits in non-phonological language. See figure 1.
Inhibition (ignoring irrelevant information)
Dyslexics show a deficit in verbal inhibition (Stroop tasks) but not in visual or simple tasks (go / no-go tasks) (Reiter, Tucha & Lange, 2005).
LI individuals show a deficit in tasks requiring inhibition in visual anti-saccade tasks and verbal Stroop tasks (Im-Bolter, Johnson, & Pascual-Leone, 2006)
Working Memory (keeping key information in mind)
Verbal working memory deficits are reported in dyslexia (word / digit span) (Menghini, Finzi, Carlesimo, & Vicari, 2011) but for visual tasks deficits have been found only when demands are increased (corsi backwards, dynamic matrix tasks) (Bacon,
U.K secondary school pupils, monolingual, aged 12 – 15 yrs.
Clinical – 30 dyslexic, 30 language impaired (LI).
Matches – 30 chronological age-matched, 30 language-matched, 30 literacy-matched (see below for measures).
No comorbid disorders, given £5 amazon voucher reward.
Background measures: Grays’s reading test and TOWRE (literacy), WIAT Listening Comprehension , Oral comprehension, Spelling (language), WASI – II Block design and Matrice Reasoning (Non-verbal IQ) and SWAN questionnaire (ADHD).
Stimuli and Method:
Participants will be completing two batteries of computer and tablet based tests assessing verbal and visual measures of inhibition, short-term and working memory.
Corsi Blocks (visual short term, working memory)
In this task participants are required to watch a block sequence play out on screen and are then required to tap it out either in the same order in which they say it (STM) or in reverse (WM).
Digit Span (verbal short term, working memory)
In this task participants are required to listen to sequences of numbers played over the headphones and then repeat the sequence aloud either in the same order (STM) or reverse (WM).
Auditory Stroop (verbal inhibition)
In this task participants are required to listen to male and female voices speaking male and female gender words (girl, boy). Their task is to ignore the gender of the speakers voice and attend to the gender of the word.
Arrow SImon (visual inhibition)
In this task participants are required to attend to the direction of an arrow and ignore its spatial location (see tablet).
rutter and yule 1975
Figure 1. The overlap between dyslexia and LI (Bishop & Snowling, 2004) plus the proposed overlap in inhibitory and working memory skills proposed by this study. N.B depends of severity of deficit, TD = typical developer, PC = poor comprehender.