Reading Difficulties PDF

Reading difficulties Intro/ summary: Reading difficulties can be defined as a range of challenges that impact an individual's ability to comprehend and process written text, with dyslexia and developmental language disorder commonly used as diagnostic terms, but can manifest themselves differently...

Reading difficulties Intro/ summary: Reading difficulties can be defined as a range of challenges that impact an individual's ability to comprehend and process written text, with dyslexia and developmental language disorder commonly used as diagnostic terms, but can manifest themselves differently. These disorders are linked to broader, cognitive challenges, with complex etiologies impacting risk factors. A better understanding of these mechanisms can help to provide a foundation for theory driven interventions, tailored to diverse learner profiles. Reading difficulties are most commonly understood as a challenge to an individual's ability to comprehend and process language. Those who experience these deficits are likely to be diagnosed with dyslexia and developmental language disorder. These disorders are linked to broader cognitive challenges with complex etiologies impacting risk factors. Competing single and multi deficit models compete for explanations, each looking at different mechanisms that impact this reading behaviour. Examining these mechanisms is crucial to develop a theory driven response to interventions, helping to improve behavioural [Definition and scope of reading difficulties ] Reading difficulties: broad range of diagnoses and cognitive behavioural profiles including: dyslexia and developmental language disorder Other behavioural phenotypes (poor comprehension/ reading difficulties) may not always meet specific diagnostic criteria Therefore an umbrella term for various language and reading disorders: each with unique, extremely complex challenges: - **Language Disorder**: Impairments in understanding or using language effectively. - **Speech Sound Disorder**: Difficulty in articulating sounds correctly, impacting speech clarity. - **Childhood Onset Fluency Disorder (Stuttering)**: Disruptions in the flow of speech, affecting communication. - **Social (Pragmatic) Communication Disorder**: Challenges in the social use of verbal and nonverbal communication. - **Unspecified Communication Disorder**: Communication difficulties that do not fit into specific categories. [Dyslexia] Learning difficulty affecting skills involved in accurate and fluent word reading and spelling (british dyslexia association 2009) Associated difficulties: - Speed of word processing - Naming speed - Spelling - Visual perception - Working memory - Attention - Planning and organization Broader cognitive level than typically assumed: suggests a complex interplay of cognitive functions 9-12% population prevalence Similar across ranges of IQ and socio economic status - Inherent cause: not mediated by social circumstances/ intellectual ability Is more frequently diagnosed in males rather than females (3:1 / 5:1 ratio) - Females are better at masking symptoms - Arnett 2017: females display more frequent reading behaviours - Wilcutt and Pennington 2000: higher ADHD prevalence amongst males -- hyperactive symptoms can mediate reading abilities Better theoretical understanding of dyslexia can guide the development of targeted interventions to address specific cognitive deficits (e.g. phonics based approaches/ working memory training) It is essential that we tailor these interventions to individuals unique profile of strengths and weaknesses [Single vs multi deficit models ] **Single deficit model:** suggests that dyslexia is caused from a single cognitive deficits (e.g. phonological processing) Attempts to find a "core" explanation to fit every diagnosis Reductionist and deterministic: cannot account for the complexity of developmental disorders **Multi deficit model:** dyslexia results from multiple interacting deficits across various cognitive domains, including genetic and environmental factors Pennington 2006: individuals with the same dyslexia diagnoses will exhibit different behavioural patterns and symptoms: could never show the same identical behaviour AS there are different influencing factors - When making diagnoses we should begin at "bottom level" behavioural approaches: this is what is most noticeable - When looking at what causes the disorder we move to "higher level" genetic and environmental factors : these provide risk and protective factors which influence the display of symptoms [Genetic basis ] Reading abilities are 40-60% heritable Swagerman 2017: reading ability was due to genetic factors: little indication for environmental influences BUT study had low sample size & was underpowered: further investigations are required Hard to distinguish between home environments and genetic factors: are reading abilities mediated by encouragement from parents or would this not already be within their genetic makeup? Stevenson 1987: 29% heritability for reading abilities & 73% for spelling \+ controlled for intelligence \+ twin studies: clear genetic basis \_ does provide genetic support but results are not 100%: environment still comes into play Hawke et al 2006: heritability of dyslexia and reading ability is high : 60-70% \+ newer study: more improved screening techniques \+ measures dyslexia directly \_ higher percentage BUT once again is not 100%: important to consider environmental factors - suggestable that it operates on a diathesis stress model Twin studies (Olsen et al 2014): also show a significant influence of the environment) - E.g. number of books within a household and how often parents read (evans et al 2010) - Mediated by socio economic status [Candidate genes ] Not a singular gene dyslexia is accountable for but rather multiple genes that increase susceptibility - **KIAA0319** : affects neural migration and radial glia adhesion - **DCDC2**: linked with severe dyslexia phenotypes and strengthens the connection between pre reading skills and later reading impairments (Gabe et al 2021) University of Glasgow (2022) : 42 genetic variants associated with dyslexia: emphasises the genetic complexity of this disorder - Dyslexia exists at a genetic level but there is no singular gene or cluster than can fully explain the condition - Highlights the need for a broader understanding of genetic contributions **Pleiotropy :** single gene has multiple effects on a different trait (e.g. FBN1 gene: impacts heart defects, eye and spinal problems, long limbs) **Polygenicity:** multiple genes will contribute to a single trait (e.g. dopaminergic (DRD4), Noradrenic (ADRA2A), serotonergic (HTR1B) all associated with ADHD) **Generalist genes hypothesis:** Plomin and Kovas (2005): genes associated with learning disabilities are related to normal variance in reading abilities - Genes affecting one symptoms of dyslexia could influence other symptoms (e.g. spelling) - Genes responsible for one learning disability can overlap with another (ADHD) -- complex interplay of risk and protective factors \+ makes logical sense that the same genes are interrelated \+ Ciulkinyte et al 2024: 174 genes interlink dyslexia and ADHD \+ McGrath and Stoodley (2019) reported co-morbidity rates of 25-40% between dyslexia and ADHD \_ although this meta-analysis had limitations due to the number of studies included. \_ diagnostic criterias were also not well established on clinical frameworks (e.g. behavioural rating scales for ADHD) \+ Genome wide association study found links between risk for dyslexia, ADHD, bipolar and schizophrenia [Gene -- enviornment interactions ] Byrne (2005): genetics can vary with life circumstances e.g. those with higher socio economic status can nurture genetic pre dispositions (e.g. intelligence = tutoring/ reading) This can pose as a protective factor or a risk factor [Environmental factors] Home learning enviornment, school conditions, socio economic status and stress Dilnot et al 2017: home literacy was a significant predictor for reading readiness Home literacy and family stress predicted attention & behaviour - Shows the importance of environmental factors [Cognitive theories of dyslexia ] Phonological deficit theory - Individuals with dyslexia are dysfunctional in phonological awarness: crucial mechanism for recognising spoken parts of sentences and worlds - E.g. noticing rhythm, alliterations and separating syllables - Individual with phonological deficit wouldn't be able to tell the difference between 'eight' and 'ate' \+ Swan and Goswami 1997: compared dyslexic children, poor reading children and aged matched controls in a task of picture naming and phonological abilities - Picture naming task: dyslexic children had poorest performance - Linguistic skills: dyslexic children performed similarly to controls for syllable and onset rhyme measures - Shows a distinction between phonemic tasks: support for the theory [Automisation hypothesis ] Dyslexia is the result of automatic processing deficit; this affects the ability to generalise learned reading behaviours \+ biological underpinnings: reduced cerebellum activation = neural basis for these difficulties Moores et al 2003: conducted experiments to assess these attention shifts between 2 target types - Participants would have to inhibit distractions and give a response to a target stimulus - Speed and accuracy was measured Dyslexic groups performed just as well as controls on attention tasks BUT would perform significantly worse when attention shifting was required Led to 2 hypotheses: 1. General resource deficit: lack the resources to perform well on attention shifting (perhaps more stimuli and resources are required for learning generalisations are necessary) 2. Automisation deficit: struggle to automise some skills & require resources for these specific areas Second experiment was conducted to analyse this further: presented normal and degraded stimuli and assessed if increasing attentional load would disproportionately affect the dyslexic group? - Found the same difficulties in recognising degraded stimuli for dyslexic and control groups - CANNOT be due to a general lack of resources - Supports the automisation deficit Support for a double deficit theory: phonological awareness and rapid naming are critical areas affected in dyslexia Baidan (1997) suggests a **third "orthographic" deficit,** highlighting the need for emphasising the complexity of dyslexia beyond simple reading issues - Ability to spell and write language - Dyslexic participants would spend longer reading and would make more errors with irregular words compared to typical readers (Siegel 1993) - Richlan et al 2011: reduced activation in the visual word form area (VWFA) during reading tasks : neurological basis for orthographic deficits e.g. Magnocellular deficit theory: dyslexia is caused by reduced sensitivity in the magnocellular system of the visual system \- this area is responsible for processing rapid visual changes \- means that those who have dyslexia have reduced motion sensitivity \+ support from Ramus et al 2003: observed abnormalities in magnocellular layers of the LGN in dyslexic brains, which caused poor performance in a tactile task \_ other studies show mixed evidence: some support with a loss of contrast sensitivity -- others studies find this to be inconsistent (Skottun 2000) Amplitude modulation hypothesis: those with dyslexia struggle with the rhythmic fluctuations of speech & this is the cause of reading and spelling difficulties - Infants will use sounds to differentiate syllables: without this adequate word recognition cannot occur : explains phonological deficits - Goswami 2023: children with dyslexia are less sensitive to slow changes in amplitude [Neural explanations ] McGrath and Stoodley (2019): strong genetic and cognitive overlap within dyslexia Neural is relatively underexplored - Distinct grey matter differences associated with BOTH dyslexia and ADHD : specifically within the right caudate (impairs executive functioning) Atypical neural circuits are more commonly found in the left inferior parieto-occipital reion and occipitotemporal cortex: affecting reading processes (habib 2000; Yan 2021) [Co-morbidities ] As mentioned there is a strong genetic overlap with ADHD And \^\^ an observed neural overlap Pennington (2006) : uses this as an advocate for the multiple deficit model - Pure, isolated developmental disorders are not realistic - In fact co morbidities are now the norm: complex interplay of genetic, neural and cognitive factors Co morbidity refers to the presence of two or more disorders within an individual Whilst these are associated it does not mean they are causative e.g. ADHD may increase the risk of dyslexia due to inhibition problems concerning reading \- shared liabilities (same factors underpin both diagnoses) Snowling et al 2019: longitudinal study to compare children with dyslexia alone, DLD alone and dyslexia + DLD to typically developing controls - Measured cognitive predictors - Findings indicated that phonological deficits remained stable in dyslexic children but worsened in comorbid cases, suggesting different developmental trajectories. - Decoding deficits were more severe in dyslexia and comorbid groups but DLD groups did remain stable \+ noted individual motor and executive deficits as this is common within the dyslexic group BUT these had no discernible influence Highlights the need to consider co morbid profiles: different associated difficulties Why do these co morbidities exist? : Shared genetic etiology: shared risk Shared cognitive bases: domain general impairments [Interventions for dyslexia ] [Evidence based interventions ] Effective interventions should be grounded in theories of skill development, whilst also promoting and targetting specific cognitive deficits Should be based on: - Theory of how a skill develops - Theory of how a skill is promoted - High quality evidence Theory based interventions: Phonological awareness training has shown significant effect sizes in improving literacy outcomes : teaching relationships between sounds and letters Effect sizes reported by the National Reading Panel (NICHD, 2000): - 0.86 on phonological awareness - 0.53 on reading outcomes - 0.59 on spelling outcomes \+ Highly effective across literacy domains. \+ Not effective outside literacy domain (e.g., maths). \+ Improved in combination with letter knowledge. Combining phonics instruction with letter-sound knowledge enhances intervention effectiveness, with synthetic phonics being particularly beneficial. High-quality evidence for interventions includes rigorous trials, educational realism, randomized controlled trials, and ecological validity. Multisensory teaching approaches: - Engages multiple senses to enhance learning : hope of better retaining information - E.g. tracing letters whilst saying their sounds \+ teachers regard this to be immensely valuable across individual and whole class learning (Boardman 2019) Theories of skill development: 1. Evidence is reviewed to see how a skill is best promoted e.g. phonemic instruction improves letter sound knowledge There are different techniques, e.g.: - Synthetic phonics (converting letters into sounds to blend) - Analytic phonics (identifying words then identifying the sounds within the word) A combined approach using synthetic phonics first, followed by analytic phonics, has shown to be most successful in practice (Price Mohr & Price, 2018; Gallagher-Mance, 2023). Interventions must consider the cost, implementation feasibility, and accommodation for individuals with varying degrees of reading difficulties. Longitudinal outcomes should be monitored to assess the long-term effectiveness of interventions. What do we mean by high quality evidence? 1. Rigorous trials 2. Educationally realistic trials (realistic that we could implement these within a classroom setting -- are they actually appropriate?) 3. Randomised controlled trials (gold standard for intervention research) 4. Scaled up classroom research (make sure realistic to settings- ecologically valid) - What is the cost of interventions? (realistic and affordable) - How are they implemented in educational settings? (How long does it take -- want the quickest intervention possible) - How can we accommodate for individuals with reading difficulties if interventions are not successful? (variability of success)