Specific learning disabilities are detrimental to one’s well-being. The repeated academic failure associated with this continues to haunt people for years after formal schooling.

A specific learning disability originally included a discrepancy-based definition. This included a discrepancy between IQ and achievement (e.g. high IQ, low reading achievement). However, the degree of discrepancy is arbitrary. This definition favours older children and children with a higher IQ. It is failure-based (e.g. waiting for children to show failure in academics).

The current definition is focused on identification with response to intervention (RTI). It includes achievement in key academic areas that is substantially below the age norm and in excess of sensory deficit (1), linguistic processes (2), attention (3) and memory (4). The prevalence rate is about 2% to 10%.

There are often social deficits in people with SLD but this may be because they get rejected and neglected by peers more often. People with SLD typically have low self-esteem and a poor self-esteem.

The DSM-5 definition of a specific learning disorder includes the following:

• Difficulties in learning and using academic skills for at least six months.
• The affected academic skills are substantially and quantifiably below those expected for the chronological age and lead to impairments in adaptive functioning.
• The learning difficulties begin during school-age years but may not fully manifest themselves until the affected academic skills exceed the individual’s limited capacities (e.g. in the case of a timed test).
• The learning difficulties are not better accounted for by other disorders (e.g. intellectual disability) or educational instruction.

The DSM-5 uses a discrepancy definition but not an IQ-discrepancy definition. There are three specifiers for severity:

• Mild
  This includes some difficulties in learning in one or two academic domains but mild enough to still function well when provided with appropriate accommodations or support services.
• Moderate
  This includes marked difficulties in learning skills in one or more academic domains. The individual is unlikely to become proficient without intensive or specialized training during the school years. Additional support may be needed.
• Severe
  This includes severe difficulties in learning skills in several academic domains. The individual is unlikely to learn those skills without ongoing intensive, individualized and specialized training for most of the school years. Performance may be inadequate even with a lot of support.

Positive psychology interventions (PPI) aim to enhance well-being by increasing positive affect, cognition and behaviour (e.g. developing hope; mastery of life). This includes teaching coping skills. This approach holds that dyslexics have unique strengths and there needs to be a focus on this. However, not all dyslexics have unique strengths and their problems need to be addressed. Positive behavioural interventions (PBI) are more common and focus on providing remedies for the problematic behaviours associated with a specific learning disorder. Changing one’s mindset can help in alleviating the negative aspects of a specific learning disorder but is not enough; treatment is necessary.

Response to intervention refers to a tiered system of empirically supported interventions. When a person fails to respond to an intervention, a more specific and intensive intervention will be used. A failure to respond to one of these interventions is a criterium for specific learning disorder. There are several stages:

1. Screening for risk (e.g. simple tests of basic prereading skills).
2. Assessing family history of reading and language difficulties.
3. Tier 1 intervention; trained classroom teachers.
4. Tier 2 intervention; additional one-to-one instruction and small groups.
5. Tier 3 intervention; special education classroom.

People in tier 1 should receive high-quality classroom instruction. People in tier two should receive additional teaching in class by the teacher and additional instruction by a reading specialist (e.g. one-to-one; small groups). People in tier three should receive help from a dyslexia specialist outside of school but should not necessarily be placed into special education. In order for RTI to be effective, tier 1 and tier 2 interventions need to be of high quality (e.g. training and focus on phonological awareness while reading for people with dyslexia).

Dyscalculia refers to limitations in mathematical understanding and includes a deficit in the number sense. It impedes activities that involve problem-solving or retrieving mathematical information (e.g. number facts). The problems in acquisition of number sense are due to a poor approximate number system (ANS). The number sense is reflected in a mental number line (e.g. where is 7 on a scale between 0 and 100).

According to the DSM-5, dyscalculia includes several aspects:

• Difficulties learning and using academic skills for at least six months.
• Difficulties mastering number sense (1), number facts (2), calculation (3) or math reasoning (4).
• Difficulties with mathematical reasoning (e.g. difficulties applying mathematical concepts).

The child often has a poor understanding of numbers (1), their magnitude and relationships (2), get lost in the midst of arithmetic computation (3) and counts on fingers to add single-digit numbers (4). The prevalence is 5% to 10% and the heritability is 43%.

According to the triple code model, numbers can be represented in the following ways:

• Auditory verbal code (i.e. three).
  This is used for arithmetical facts learned by heart (e.g. multiplication table).
• Visual code for Arabic digits (i.e. ‘3’).
  This is used for parity judgements and multidigit operations.
• Analogue magnitude code (i.e. ***)
  This is used for magnitude comparison and approximate calculation.

In mathematics, all three codes need to cooperate. The defective number module hypothesis states that in dyscalculia there are problems with the quantities (i.e. analogue codes) and not only symbols (i.e. problems understanding and representing quantities). This means that dyscalculia is a broader disorder. The access deficit hypothesis states that there are problems with accessing quantities via numbers (i.e. symbols) and not with quantities themselves.

These hypotheses can be assessed using numerical magnitude comparisons. This can be symbolic (i.e. comparing the number ‘1’ and ‘9’) or non-symbolic (i.e. comparing *** and *****). Another way to assess it is by using approximate addition tasks. This can be symbolic (i.e. approximate two numerals) or non-symbolic (e.g. approximate two sets of dots).

Children with severe mathematical difficulties (MLD) are similar to children low achievement but both are slower than regular achievers on a symbolic task. There are no group differences in non-symbolic tasks. Children with mild problems are more accurate in approximate addition than children with severe problems.

This provides evidence for the access deficit hypothesis. The distance effect (i.e. ratio effect) states that answers become slower and less accurate when comparing magnitudes and the difference between the magnitudes is small (e.g. compare four and five digits).

Speaking includes going from a concept to a spoken sound. Reading going from a written word to a sound to a concept. There needs to be a good connection between orthography and phonology. There are different phases of reading development:

1. Pre-alphabetic phase (i.e. ‘reading’ based on visual features).
   In this stage, the child knows general printed concepts (e.g. McDonalds) and the child recognized incidental visual features of words. However, the child does not possess letter-sound correspondence.
2. Early alphabetic phase
   In this stage, the child knows some letter-sound correspondences and the child demonstrates early phonological and phonemic awareness skills of syllables (e.g. reading each letter separately and then combining them; b a ll, ball!).
3. Later alphabetic phase
   In this stage, the child begins to recognize sight words with automaticity and uses phoneme-grapheme correspondences. The child demonstrates understanding of basic phonemic awareness.
4. Consolidated alphabetic phase
   In this stage, reading becomes increasingly automatic. The child demonstrates advanced phonemic awareness skills (e.g. deletion; substitution; reversal of phonemes).

Children first show letter by letter decoding (e.g. b-a-t). There is no automatic phonology. For adults, there is parallel activation of letters (1), a word superiority effect (2) and automatic phonology (3). Children with dyslexia decode letter by letter for a longer period of time and have problems in integrating.

Spelling is learned through self-teaching (i.e. orthographic learning). This means that a child sees a word one has already heard and then reads a text where this word is used. The child then knows how to spell this word. This requires decoding from visual to auditory code. Dyslexic children learn how to spell words but need more exposure using orthographic learning.

For dyslexia, the basic characteristics and causes are understood well enough for identification and treatment. The behavioural deficits are a solid basis for identification. The prevalence of dyslexia is 3.6%. About 8.8% of the population are poor readers. There is a large genetic component. The left-hemisphere posterior brain system does not respond appropriately when reading in people with dyslexia.

According to the DSM-5, impairment in reading includes:

• Difficulties learning and using academic skills as indicated by one of the following symptoms for at least six months:
  • Inaccurate or slow and effortful word reading.
  • Difficulty understanding the meaning of what has been read.
  • Difficulties with spelling (e.g. omit vowels).

It includes problems with word reading accuracy (1), reading rate or fluency (2) and reading comprehension (3). According to the Dutch health system, dyslexia is a specific reading and spelling disability that has a neurological basis and is caused by cognitive processing problems in the connection of orthography and phonology. Other language processing skills are less impaired and specific reading and spelling problems persist despite education.

With dyslexia, there is a wide IQ range. IQ is not a strong predictor of intervention responses. It includes people at the low end of normal reading distribution and requires treatment. Dyslexia falls on a continuum but is chronic as people do not ‘grow out of it’. The identification and targeted treatment of dyslexia are important for well-being (1), health (2) and success (3).

There is a phonological deficit (i.e. problems in decoding sound-symbol associations) (1), comprehension problems (2) and fluency problems (3) in dyslexia. This is not caused by general cognitive limitation or environmental factors (e.g. poor instruction).

Reading comprehension consists of phonological decoding and language comprehension. Slow phonological decoding leads to a slow word reading fluency and this leads to poor reading comprehension. Fast decoding is important because working memory focused on phonological decoding does not have capacity for comprehension. Therefore, the more efficient lower-level word processes are, the more cognitive attention can be directed to higher-level processes at the sentence and text level. Many people with dyslexia become accurate readers but fluency problems are more persistent. This means that reading remains effortful (1), slow (2) and laborious (3).

The phonological deficit theory states that in dyslexia there is a deficit in simple phonological processing leads to dyslexia. The reduced awareness of sound structure leads to problems making connections between spoken and written language. There are underspecified word representations (e.g. not sufficiently discriminative). Decoding is essential for new words because there are no word representations in memory.

In the double deficit model, there can be a deficit in phonological awareness or rapid naming for dyslexia. Either deficit is sufficient for dyslexia although children with both deficits likely have worse outcomes. Rapid automized naming (RAN) refers to a mini-circuit of the later-developing reading circuitry. It allows for ease of access to representation stored in memory. RAN tasks include timed naming of familiar stimuli presented repeatedly in a random order. Pause and thinking time are predictive of reading performance in later life rather than articulation time. The relationship between RAN and reading is strong and lasting but only for poor readers. It appears to predict reading ability in later life.

Deficits in phonological awareness and rapid naming predict dyslexia across orthographies. Deficits in phonological awareness are more predictive of dyslexia in opaque orthographies (e.g. English) and deficits in rapid naming are more predictive of dyslexia in transparent orthographies (e.g. Dutch). An opaque orthography exists when the correspondence between phonemes and graphemes are not consistent. A transparent orthography exists when there is a high correspondence between phonemes (i.e. sounds) and graphemes (i.e. letters). The orthographic depth of a language dictates when the shift from reliance on phonology to fluency-related skills occurs.

The magnocellular theory is a visual model of dyslexia and states that people with dyslexia are less sensitive for contrasts and movements and show less stable eye-fixations. Visual stress may play a role in reading problems as visual deformation (e.g. blurry letters) may occur or visual problems (e.g. headache) may be the result of reading. The deficits in the visual theories are very specific and the relationship with reading is unclear. It also does not have an explanation for specific word-level reading problems. These problems occur more often in people without dyslexia than in people with dyslexia.

The multideficit model holds that multiple deficits (e.g. phonological problems; visual problems; insecurity) lead to dyslexia.

The common deficit account holds that comorbid dyscalculia and dyslexia can be explained by phonological problems. In this case, there is partial overlap in the problems so there are fewer problems in total in the comorbid group. However, reading difficulties seem to aggravate rather than cause math difficulties.

The domain-specific deficit account states that dyscalculia and dyslexia have two separable cognitive profiles. According to this account, dyslexia consists of deficits in phonological awareness (1), phonological short-term and working memory (2) and lexical access (3). Phonological short-term and working memory may impact the development of number fact knowledge. Deficits in lexical access may explain dyscalculia because it is needed to store and retrieve orthographic information.

Comorbid dyslexia and dyscalculia seem to have additive problems and the problems appear to be independent of each other. This provides evidence for the domain-specific deficit account.

Non-verbal learning disability (NLD) refers to having significant weaknesses in visuospatial performance areas. However, these children have significant strengths in verbal areas (e.g. single word reading). They experience problems with learning from visual information and have poor visual-constructive skills. This means that what is seen is difficult to translate into motor movement (e.g. build Lego from an example). There are also attention problems when visual information is offered and poor proprioception. It is not clear what the essential characteristics are and there is no clear explanatory theory. It may be due to damage to the white matter tracts. The prevalence is 0.1% but it overlaps with Asperger’s syndrome, meaning that the actual prevalence may be underestimated.

Dysgraphia refers to a deficit in written expression. The deficits include organization (1), spelling (2), grammatical structure (3), punctuation (4), revising (5), planning (6), transcribing (7) and translating ideas into written content (8). There may be problems with handwriting (1), spelling (2) and global deficits (3). The prevalence rate is 1.3% to 2.7% in early primary school and 6% to 22% in middle school.

Dyspraxia refers to a developmental coordination disorder (DCD) and deficits include balance (1), fine and gross motor skills (2) and manual dexterity (3). There are problems in posture, movement and coordination. The prevalence is 5% to 6% and is more common in males than in females. Motor milestones are often delayed and it may be caused by a central nervous system dysfunction.