Neurolinguistic patterns of children with reading disabilities: preliminary results
Norberto Cardoso-Pereira1,2, Maria Armanda Costa2, Manuela Guerreiro3
1NeuroCog – Centro de Reabilitação da Lesão Cerebral, Portugal 2Laboratory of Psycholinguistics, Faculdade de Letras da Universidade de Lisboa, Portugal 3Faculdade de Medicina da Universidade de Lisboa, Portugal
Table 1 - Sample Characterization.
Discussion
Previous studies have reported the following deficits in children with learning disabilities, specifically: 1. Sequence problems (Conde-Guzón et al. 2009); 2. Difficulty processing
temporal indexes (Crespo & Narbona, 2006); 3. Poor discrimination between rapid and simultaneously auditory stimulus (Crespo & Narbona, 2006; Nicolson & Fawcett, 2010);
4. Reduced processing velocity in linguistic and non-linguistic activities (Crespo & Narbona, 2006); 5. Temporal perception deficit (Crespo & Narbona, 2006); 6. Verbal processing
(Loge et al., 1990); 7. Verbal fluency errors (Carte et al., 1996); 8. Working memory, phonological and short-term verbal memory (Crespo e & Narbona, 2006; Muñoz & Carballo,
2005; Barkley, 1997; Nicolson & Fawcett, 2010); 9. Symbolic game difficulties (Muñoz & Carballo, 2005); 10. Tactile recognition errors (Muñoz & Carballo, 2005); 11. Poor visual
discrimination (Muñoz & Carballo, 2005); 12. Grapheme-phonemic decoding problems (Crespo & Narbona, 2006); 13. Deficits in Attention, decoding, memory and executive func-
tion (Buiza-Navarrete et al., 2007); 14. Poor balance and motor skills (Nicolson & Fawcett, 2010).
Conclusions
For both reading groups there is highly word-frequency and word-length effects. Words that were more difficult to identify received more fixations than words that were relatively
easier to process. The length and frequency effects were observed both for the initial encounter on a word as well as for frequency of making a regression to the target word. The
effects were largely due to more difficult words attracting multiple fixations on them. This was particularly the case with the word-length effect. In addition, word frequency also in-
fluenced the duration of initial fixation on the target word. It was longest for low-frequency words and shortest for medium-frequency words. We were able to conclude that ADHD
and dyslexic children share atypical eye movement patterns in the core of their reading disabilities when decoding words of different length and frequency, due to different underly-
ing cognitive mechanisms that were not present in the control group.
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Introduction
Learning disabilities (LD) - neurobiological condition, involving deficits in cognitive processes, and ability to learn (National Joint Committee on Learning Dis-
abilities [NJCLD], 2008). LD of scholastic skills are characterized by significant impairments in acquisition of reading, spelling or arithmetical skills (Kohli,
Kaur, Mohanty et al., 2006). Some subgroups of children with LD may have more difficulties with information processing speed, short-term and working
memory, and auditory processing when compared with children of the same age (Macintyre & Deponio, 2003). There is a need to understand both the dis-
tinctive aspects of and the considerable overlap between each specific learning disorder (SLD) as they may have different underlying mechanisms (Kohli,
Kaur, Mohanty et al., 2006).
Reading disabilities (RD) - common feature among LD. The main challenges children with RD face are accurate word recognition and decoding, reading flu-
ency, and spelling (Oyler, Obrzut, Asbjornsen, 2012). Most often the co-morbidity along with this condition is Attention Deficit and Hyperactivity Disorder
(ADHD) and developmental dyslexia (de Jong, Van De Voorde, Roeyers et al., 2009). While the linguistic semiology related to learning disabilities has been
extensively studied, there are only a handful of studies till date examining neuropsychological profiles of children with reading disabilities (Conde-Guzón et
al., 2009).
Developmental dyslexia - unexpected, specific, and persistent failure to acquire efficient reading skills despite conventional instruction, adequate intelli-
gence, and sociocultural opportunity (American Psychiatric Association [APA], 2002). It has an estimated prevalence of 5 to 10% (Flynn & Rahbar, 1994), is
the reading disability that most adversely affects academic performance (Artigas-Pallarés, 2009). This condition encompasses a host of deficits, and alt-
hough massively studied, numerous doubts exist regarding the interrelationship between various cognitive functions (Nicolson & Fawcett, 2010).
ADHD - has a 5 to 9% prevalence in children with school age (Shaywitz & Shaywitz, 1996) and in 15 to 40% of cases it appears as a comorbid condition
with dyslexia (Holborow & Berry, 1986). Children with ADHD present non diagnosed deficits in oral language, in comprehension and in syntax formation and/
or pragmatic rules. Interestingly, these deficits appear frequently in the absence of phonological processing deficit (Bruce, Thernlund, Nettelbladt, 2006).
Methodology
Participants - 21 children, with ages between 8 and 9 years, divided into three groups: a control group (non-dyslexic), a group with dyslexia and another with
ADHD. All participants were submitted to a neuropsychological evaluation to assess cognitive functions such as attention, executive function, working
memory and visuo-perceptive functioning. Reading performance was measured with linguistic instruments and eye-tracking. The three groups were matched
on the level of scholarship. Inclusionary criteria for participants in all groups were: 1) a score of at least 85 on the Wechsler Intelligence Scale for Children, 2)
no evidence of neurological problems, 3) no uncorrected visual acuity or auditory deficits, 4) exposure to adequate instruction, 5) no serious economic prob-
lems, and 6) Portuguese as the primary language spoken in the home.
Apparatus - Eye movements were recorded using IVIEW XTM HI-SPEED from SensoMotoric Instruments.
Materials - All participants read the same 4th-grade-level text from the 2013 Portuguese national assessment. This text was adapted so that some reading
errors would be generated. The story, 264 words long, dealt with deep sea exploration. From the text, words of variable length and frequency were chosen.
To allow for an orthogonal comparison of word length and word frequency, a set of medium and low-frequency words was chosen for each of the following
word lengths: short (4-6 Letters), medium (7-10 letters), and long (11-14 letters). 10 words of each kind were identified in the stimulus texts. Fixation counts,
single fixation duration, first fixation duration, first pass gaze duration and second pass gaze duration landing in the target words were analyzed.
Procedure – The eye tracker was calibrated by using nine fixation points extending the visual field where the text was presented. Participants were then
asked to read silently the text. A few questions about the text were immediately asked after the text was read.
Table 2 - Material.
Encontro Ciências 2016
Results
Dyslexic children had higher results than ADHD children in the following cognitive and linguistic measures: lexical knowledge (X2=8.720, p<.05); episodic long-term memory
(X2=5.312, p<.05); visual attention and immediate visual memory (X2=5.795, p<.05); perceptual analysis (X2=4.439, p<.05); organization and visual-spatial thinking (X2=5.096,
p<.05); verbal IQ (X2=6.630, p<.05); performance IQ (X2=8.672, p<.05); full scale IQ (X2=8.208, p<.05) and phonological awareness (X2=5.333, p<.05).
Eye-tracking - Comparatively to the control group, dyslexic children have higher first fixation durations for short medium-frequency words (X2=5.633, p<.05), higher fixation counts
for long short-frequency words (X2=4.108, p<.05), higher first fixation durations for long low-frequency words (X2=7.500, p<.05), higher second pass gaze durations for long low-
frequency words (X2=4.033, p<.05), higher single fixation durations for long medium-frequency words (X2=6.194, p<.05), higher first fixation durations for medium low-frequency
words (X2=4.800, p<.05), higher first fixation duration for medium medium-frequency words (X2=4.800, p<.05) and higher first pass gaze duration for medium medium-frequency
words (X2=6.533, p<.05). Comparatively to the control group, ADHD children have higher single fixation durations for long medium-frequency words (X2=8.900, p<.05) and higher
first fixation durations for medium medium-frequency words (X2=6.765, p<.05). No statistically significant differences were found between dyslexic and ADHD children.
Neuropsychological Evaluation
Instruments Subtests Function Evaluated
WISC-III: Verbal
Information Long term episodic memory
Similarities Verbal abstraction
Arithmetic’s Mental calculus; working memory
Vocabulary Lexical knowledge
Comprehension Social rules knowledge
Digit span direct Immediate verbal-auditory memory
Digit span reverse Working memory
WISC-III: Performance
Picture Completion Lexical access capacity; visual attention
Picture Arrangement Perceptive analysis
Block design Visual organization and visual-spatial processing
Puzzles Perceptive integration
Coding Associative learning
Mazes Eye-hand coordination
Raven Coloured Matrices (CPM) N/A Non-verbal general intelligence
Rey Complex Figure Copy Visual perception functioning
Memory (3') Delayed visual memory
Linguistic Evaluation
Instruments Subtests Function Evaluated
ALEPE
Word reading
Phonological awareness and Written Word Processing
Phoneme Letter Reading
Rhyme Pseudo-Word
Reading
O REI - Fluency and Preci-sion Reading Test
N/A Fluency and precision
TCL 3 - Reading Comprehen-sion Test
Literal Comprehen-sion
Comprehension Performance Inferential Compre-
hension
Critical Compre-hension
Reorganization
Eye-Tracking
Text Subtext Target Words
Berlengas 1, 2
Extension
Short lenght words [4-6]
Medium lenght words [7-10]
Long lenght words [11-14]
Slide 1 Frequency
Low frequency 0-1000
Slide 2 Medium frequency 1001-10000
Slide 3
Variables
Fixation Count
Single fixation duration [ms]
First fixation duration [ms]
First pass gaze duration [ms]
Second pass gaze duration [ms]
Objectives
1. Determine the neurolinguistic profiles that underlie reading disabilities (RD) in children with dyslexia and ADHD - inattentive subtype.
2. Study word-frequency and word-length effects in children with dyslexia and ADHD.
3. Evaluate how reading is restricted by limited cognitive resources, namely attention, memory, visual-spatial and visual-constructive abilities, and execu-
tive functioning.
Table 7 - Eye-Tracking.
Table 3 - Target words: Slide 3.
Control Group (n=7) Dyslexia (n=7) ADHD (n=8)
Scholarship 4th grade 4th grade 4th grade
Age 8,60±0,24 9,20±0,37 9,42±0,30
N 21
Table 8 – Cognitive and Linguistic measures.
Table 4 - Eye movement pattern: Dyslexic children.
Table 5 - Eye movement pattern: ADHD children.
Table 6 - Eye movement pattern: Control group.
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