Dyslexia

Question 1

Dyslexia definition (DSM)

Answer 1

A person having a specific learning disability with impairment in reading, when reading achievement, as measured by individually administered standardised tests of reading accuracy or comprehension, is substantially below that expected given the person’s chronological age, measured intelligence, and age-appropriate education.

Question 2

Shorter dyslexia definition

Answer 2

A pattern of learning difficulties characterized by problems with accurate or fluent word recognition, poor decoding, and poor spelling abilities.

Question 3

How common is dyslexia? (Rutter et al, 2004; Rose, 2009)

Answer 3

Rutter - Affecting about 3- 6% of children, with more boys than girls
Rose - Prevalence is variable

Question 4

Symptoms of dyslexia in pre-school

Answer 4

Delayed speech development
Speech problems e.g. jumbling up phrases
Little appreciation of rhyming words
Difficulty learning the alphabet

Question 5

Symptoms of dyslexia in school children

Answer 5

Problems learning names and sounds of letters
Unpredictable and inconsistent spelling
Confusing the order of letters in words
Making errors when reading aloud
Struggling to learn sequences e.g. days of the week
Poor handwriting
Taking longer than normal to complete written work

Question 6

How is dyslexia diagnosed?

Answer 6

1. Rule out other issues with vision, hearing and other conditions like ADHD
2. Parents and teachers supply general health, developmental and medical history and how a child performs on certain tasks
3. Child completed a set of cognitive measures assessing IQ, reading, writing, language, memory, reasoning and processing speed

Question 7

Pennington and Smith (1988)

Answer 7

40% of boys and 18% of girls with a dyslexic parent are also dyslexic

Question 8

DeFries et al (1987)

Answer 8

Concordance rate is higher in identical twins than non-identical twins

Question 9

Cardon et al (1994)

Answer 9

Shorter genes on chromosome 6 could be a cause for dyslexia

Question 10

Grigorenko et al (2001)

Answer 10

The language part of the brain is smaller than neurotypical in dyslexic people

Question 11

Brunswick et al (1999)

Answer 11

Compared dyslexics to controls during reading, less activation in the left inferior and middle temporal lobe, left frontal operculum, and cerebellum in dyslexics

Question 12

Paulesu et al (1996)

Answer 12

When rhyming, those with dyslexia showed less activation in Wernicke area and left insula. This suggests a disconnection between posterior and frontal language areas

Question 13

Environmental factors of dyslexia

Answer 13

1. Poor SES
2. Lack of literacy related skills at home
3. Lack of schooling
4. Different languages

Question 14

Languages and dyslexia

Answer 14

Some languages have regular sound-spelling correspondences, and this limits dyslexia.

Question 15

Poor performance tasks for dyslexics

Answer 15

• Single word reading
• Word Recall (a verbal short-term memory task)

Question 16

Three aspects of reading

Answer 16

Semantics
Orthography
Phonology

Question 17

Phonology definition

Answer 17

Skills that involve dealing with speech sounds

Question 18

Skills in phonology

Answer 18

Implicit skills – Skills that are automatically engaged (verbal short-term memory, Rapid Automatised naming)
Explicit skills – Skills related to reflecting upon and/or manipulating speech sounds (phonological awareness / sensitivity)

Question 19

Bradley and Bryant (1983)

Answer 19

Followed 400 children from aged 4 to 8

Children’s phonological awareness at aged 4 was a good predictor of reading and spelling at aged 8, even when controlling for IQ, memory and social class

Question 20

Manis et al (1993)

Answer 20

Those with dyslexia show poorer performance than controls on phonological awareness tasks e.g. rhyme tasks

Question 21

Snowling et al (1986)

Answer 21

Dyslexic people show poorer performance on simple phonological processing tasks like nonword repetition and
picture naming

Question 22

Wolf and Bowers (1999)

Answer 22

Dyslexics have deficits in automised naming

Question 23

Hulme (1981)

Answer 23

Children with dyslexia have been found to have impaired verbal short-term memory, but in tact visual short-term memory

Question 24

Visual Perceptual Theory

Answer 24

Reading requires recognition of letters and conversions to sounds (called grapheme-phenome mapping).

The magnocellular visual pathway is responsible for this task between the eyes and the brain. They also detect contrast, motion, and rapid changes in the visual field.

For dyslexic people, retinal images persist longer than appropriate, resulting in an excess of visual information that creates a masking effect and a reduction in visual acuity.

There is a lack in the parvocellular pathway as well.

Question 25

Stein (2019) - Magnocells in the retina

Answer 25

In neurotypical people, a static object can begin to jitter because of the Magnocells. The period of jitter is short for dyslexics

Question 26

Stein (2019) - Magnocells in the Lateral Genicular Nucleus.

Answer 26

Post-mortem studies (and now structural MRI studies) have revealed thinner Magnocell layers in the LGN in dyslexics compared to controls.

Question 27

Stein (2019) - Magnocells in the Striate Cortex

Answer 27

Dyslexics show significantly different performance on the flicker fusion task

Question 28

Stein (2019) - Cortico magno systems.

Answer 28

The visual motion area V5 is active during visually guided movement. In dyslexics the activity in response to moving stimuli is reduced

Question 29

Stein (2012)

Answer 29

90% of studies since 2000 examining magnocellular impairments in dyslexia had found some supportive evidence

Question 30

American Academy of Pediatrics (2009)

Answer 30

“Any possible magnocellular deficit has insufficient evidence on which to base treatment”

Question 31

Franceschini et al (2012)

Answer 31

Tested children on 2 visuospatial tasks: visual search and spatial cuing. Children who showed worse performance were the worst readers.

Question 32

Bosse et al (2007)

Answer 32

There is a bigger difference in the visual attention span

Question 33

Saksida et al (2016)

Answer 33

Deficits in visual attention span may only affect a small proportion of individuals with dyslexia

Question 34

Nicolson and Fawcett (1990)

Answer 34

Problems in the automatization of new skills are at the core of the difficulties dyslexic children experience

Question 35

Rae et al (1998)

Answer 35

Dyslexics show abnormal cerebellar anatomy and chemistry

Question 36

Stoodley and Stein (2011)

Answer 36

Dyslexics have impaired activation of the cerebellum during reading

Question 37

Leiner (1993)

Answer 37

fMRI under-activation of the cerebellum is the most reliable distinction of all MRI studies comparing dyslexics with controls

Question 38

Moore et al (2017)

Answer 38

There is a close correlation between cerebellar volume measured in infancy and people’s eventual reading ability

Question 39

Interventions (Vaughn and Roberts, 2007)

Answer 39

• Phonemic awareness
• Phonics
• Spelling/writing
• Fluency
• Vocabulary
• Comprehension

Question 40

Coloured filters (Stein, 2019)

Answer 40

A convenient way of enhancing M- cell function is simply to view text through filters that selectively transmit yellow light

Can be either yellow or deep blue

Question 41

Yellow filters (Harries et al, 2015; Ray et al, 2005)

Answer 41

¼ of dyslexics can improve their visual symptoms, motion sensitivity, vergence eye control and, most importantly, their reading, by using such yellow filters

Question 42

Hankins et al (2008)

Answer 42

The yellow paper might help not because of the Magnocells, but by activating the recently discovered set of retinal ganglion cells which contain melanopsin

Question 43

Bachmann and Mengheri (2018)

Answer 43

Common to use different fonts to help dyslexic people

Question 44

Dawson et al (2019)

Answer 44

Assistive technologies eg Ease of Access also help dyslexics.