What are Learning Disabilities?

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The learning disability category has become the fastest-growing category within special education. In the past decade, the number of children identified by the schools as learning-disabled has risen from one percent of the school-age population to 5 percent. Funds spent on special education services for learning-disabled children have increased from five percent of funds distributed by the Office of Special Education Programs in 1978 to almost 50 percent in 1990. Prof. Ashoka, in his brilliant research paper, tells us how times have changed and parents are aware that learning disability can be dealt with, in the Special Feature, exclusively for Different Truths.

Despite massive expenditures on public education, illiteracy is still a serious problem in our society. A recent survey reported that 23 million people in the workforce cannot read or write well enough to compete in the job market. Another study found that fewer than half of all high school graduates could compute the change that would be received from $3.00 for two items ordered from a lunch menu.

In the past, when children had difficulty learning in school, they simply dropped out and entered the labour force or went to work on the family farm. Those who remained in school were often lumped together with children who were blind, deaf, mentally retarded, or emotionally disturbed. They were then segregated in separate classrooms and even separate schools. In some cases, placement in special education amounted to little more than “warehousing” the child.

This situation has changed dramatically in the past few decades as we have come to see formal education as crucial for success in life. Today, parents are not willing to accept the explanation that their children are “lazy,” nor will they allow them to be isolated from their peers and placed in special classes. In increasing numbers, parents are demanding individualised programs and special services, provided in a mainstream setting.

As a result, the learning disability category has become the fastest-growing category within special education. In the past decade, the number of children identified by the schools as learning-disabled has risen from one percent of the school-age population to 5 percent. Funds spent on special education services for learning-disabled children have increased from five percent of funds distributed by the Office of Special Education Programs in 1978 to almost 50 percent in 1990. 

There has also been a dramatic increase in funding for research in learning disabilities. In 1980, the National Institute of Child Health and Human Development spent $2.9 million on projects related to reading disorders. In 1990, the amount spent was $7.7 million. A particularly exciting development has been the establishment of three learning disabilities research centers. Located at Yale University, Johns Hopkins University, and the University of Colorado, these centers bring together scientists from many disciplines to collaborate on research on all aspects of learning disabilities. These efforts have already begun to bear fruit in the form of increased knowledge about the causes of learning disorders and the most effective methods for treating them. 

Who is the Learning-Disabled Child?

How do you recognise a child who has learning disabilities? As Sally Smith3 has so aptly pointed out, there are “no easy answers,” but often we find that the learning-disabled youngster is one who:

  • Can recite the batting average of every player in the American League since 1952 but cannot remember the names of his classmates. 
  • Reads “saw” for “was,” “god” for “dog,” and “dog” for “doughnut,” so that what he thinks he has read bears no relationship to what is actually on the page in front of him. 
  • Is very verbal and reads voraciously but subtracts 7 from 12 and comes up with 15. 
  • Earns scores in the superior range on intelligence tests but baulks at doing even minimum amounts of written work.

Confronted with a child like this, parents vacillate between scratching their heads and tearing out their hair. How, they wonder, can he sound so smart and act so dumb? How can he be so bright yet perform so abysmally in the classroom?

What’s wrong with these children? Are they, as one controversial book4 suggests, able-minded underachievers who have the ability but not the “will” to do the work? Do they suffer from psychological problems which result in “work inhibition”? Are they just lazy?

Learning Disabilities Defined

It is a safe bet that there is at least as much confusion surrounding the term “learning disability” as there is about the term “hyperactivity.” Certainly, it is an area in which myths and misunderstandings abound.

Part of the confusion stems from the way in which learning disabilities are defined. The term “learning-disabled” refers only to children who fail to learn despite an apparently normal capacity for learning. This means that not all children who perform poorly in school can be considered learning-disabled. For example, a child whose academic performance is deficient because he is blind, deaf, or paralyzed is not considered learning-disabled, nor do we use the term to refer to a child whose learning difficulties stem from a generally low level of intelligence (mental retardation) or severe environmental deprivation.

In 1975, Public Law 94-142, the Education for All Handicapped Children Act, was passed. This law provided the following definition of a learning disability: “Specific learning disability means a disorder in one or more of the basic … processes involved in understanding or in using language, spoken or written. [This may take the form of] imperfect ability to listen, think, speak, read, write, spell or do mathematical calculations.”

Federal guidelines state that in order for a child to be considered learning- disabled, there must be a significant discrepancy between the child’s potential for learning (as assessed by intelligence tests) and his actual academic achievement in one or more of seven areas. These include:

  • Oral expression (speaking)
  • Listening comprehension (understanding)
  • Written expression
  • Basic reading
  • Reading comprehension
  • Mathematics calculation
  • Mathematics reasoning (problem-solving)

On the face of it, this approach to defining learning disabilities appears straightforward. Unfortunately, since the magnitude of the discrepancy was not specified in the federal guidelines, all sorts of misunderstandings and confusion have followed. Should we consider a 10-point difference between intelligence test scores and achievement test scores a “discrepancy”? A 20-point difference? If the child is a year behind his peers in reading, is this a “significant” delay? Or should we insist that he be two or more years behind in order for him to be considered learning- disabled?

Quibbling over the fine points of a definition may seem like nit-picking, but the way in which we define learning disabilities has very important implications for determining who is eligible to receive remedial and support services. Too restrictive a definition will result in denying these services to children who truly need them. On the other hand, if we define the condition too loosely, we will include many normal learners who do not need special education services. Since these services are costly, this will put an impossible fiscal strain on school systems at a time when schools throughout the country are facing budget cutbacks.

Researchers, too, need a clear definition of learning disabilities. Lack of agreement concerning a definition has made it difficult to interpret research results and to compare findings from one study to the next. This has caused no end of confusion when researchers have tried to estimate prevalence rates (since rates vary widely depending on the definition used), identify associated problems, and determine what kinds of treatment programs are most effective.

Currently, the most widely accepted approach to defining a learning disability calls for a discrepancy of at least 20 points between intelligence test scores and achievement test scores. Using this definition, it is estimated that learning disabilities occur in about 10 percent of the U.S. population. Learning disabilities affect boys and girls in approximately equal numbers, although more boys than girls are referred for help. The reason for this remains unclear: perhaps boys are more severely affected or, as some have suggested, are more disruptive and troublesome to parents and teachers.

Specific Learning Disabilities

Researchers have used all kinds of classification schemes to categorize and study different types of learning disabilities. Some, for example, have categorized learning disabilities on the basis of specific processes which they think are involved in learning. These include visual and auditory perception, sequencing, visual-motor integration, and memory processes.

For the purpose of our discussion, we have simply divided learning disabilities into two broad groups: 1) those which involve auditory-verbal processes, resulting in reading disorders and other language-based learning problems; and 2) those which involve visual and motor (nonverbal) processes, resulting in poor handwriting, difficulties in mathematics, and deficits in certain social skills. Table 2 provides an overview of the areas of learning and achievement which are affected by each set of skills.

Reading Disorders and Other Language-Based Learning Disabilities

Reading disorders, often referred to collectively as “dyslexia,” are by far the most common of the learning disabilities, accounting for the vast majority of all referrals for diagnosis and remediation. They are generally the most troublesome as well, with consequences which are more pervasive and far-reaching than those of other kinds of learning disorders. Sloppy handwriting, weak math skills, and poor coordination may have only mild nuisance value in daily life, especially in the adult years. Many otherwise competent and successful people cannot balance a chequebook or catch a baseball, but these deficits have little impact on their overall ability to function in society.

Poor reading ability, on the other hand, can cause significant life problems not only during the school years but well past the time an individual leaves formal schooling behind. Reading skills are important in everyday life. And although reading disorders certainly do not preclude success in adult years, they continue to present practical problems in many aspects of personal and professional life.

Finally, reading disorders are the most misunderstood of the learning disabilities. It is ironic—and unfortunate—that the public continues to be bombarded with misinformation about reading disorders since we actually know a great deal about the specific skill deficits associated with them.

Skill Deficits in Reading Disorders

A host of explanations have been advanced for reading disorders, including faulty eye movements, problems with visual perception or coordination between visual and motor functions, failure of the eyes to work together, and so on. These theories have given rise to one of the most common misconceptions about dyslexia.

Myth: Dyslexia is caused by problems with visual-spatial functions.

Fact: Dyslexia is due to impaired language-processing skills.

It is not difficult to understand why this myth is so widespread. The connection between the eyes and reading is an obvious one (try reading with your eyes closed!), and in fact, there are differences between good and poor readers in the patterns of eye movement during reading. Many poor readers also have difficulty with reversals, confusing the letters “b” and “d,” for example, and reading “was” as “saw.”

Research evidence, however, clearly indicates that reading-disabled individuals actually have impaired language-processing skills, especially in what are called “phonological processes.” As Dr. Bruce Pennington, a prominent neuropsychologist at the University of Denver, explains:

Over and over again when we read, we must translate printed letter strings into word pronunciations. To do this, we must understand that the alphabet is a code for phonemes, the individual speech sounds in the language, and we must be able to use that code quickly and automatically so that we can concentrate on the meaning of what we read. The difficulty that dyslexics have with “phonics,” the ability to sound out words, makes reading much slower and less automatic and detracts considerably from comprehension.

In addition to difficulty understanding written material, many children with reading disorders have problems understanding what they hear. Because they have problems distinguishing between similar sounds (for example, “mine” versus “mind”), their listening comprehension may be impaired, especially in a noisy environment in which other sounds compete with the main speaker.

Levels of Processing Related to Learning Disability/Disability Characteristics

Auditory/Verbal Conceptual

  • Language semantics—word meaning, definition vocabulary
  • Listening comprehension—understanding and memory of overall ideas
  • Reading comprehension—understanding, and memory of overall ideas
  • Specificity and variety of verbal concepts for oral or written expression

Verbal reasoning and Logic Automatic       

  • Early speech—naming objects
  • Auditory processing—clear enunciation of speech, pronouncing sounds/syllables in correct order
  • Name colours
  • Recall birthdate, phone number, address, etc.
  • Say alphabet and other lists (days, months) in order
  • Easily select and sequence words with a proper grammatical structure for oral or written expression
  • Auditory “dyslexia”—discriminate sounds, especially vowels; auditory blend sounds to words, distinguish words that sound alike, e.g., mine/mind
  • Labelling and retrieval reading disorder—perceives auditory and visual okay but continually mislabels letters sounds, common syllables, sight words (b/d, her/here)
  • Poor phonic spelling
  • Poor listening/reading comprehension due to poor short-term memory, especially for rote facts
  • Labelling and retrieval math disorder—trouble counting sequentially, mislabels numbers (16/60), poor memory for number facts and sequences of steps for computation (e.g., long division)
  • Recall names, dates, and historical facts
  • Learn and retain new science terminology

Visual/Motor Conceptual

  • Social insight and reasoning—ability to understand strategies of games, jokes, motives of others, social conventions, tact
  • Math concepts—use of zero in operations; place value, money equivalences, missing elements, etc.
  • Inferential reading comprehension; drawing conclusions
  • Understanding relationship of historical events across time; understanding science concepts
  • Structuring ideas hierarchically; outlining skills
  • Generalisation abilities
  • Integrating material into a well-organized report


  • Assembling puzzles and building with construction toys
  • Social perception and awareness of the environment
  • Time sense—doesn’t ask, “Is this the last recess?”
  • Remembers and executes correct sequence for tying shoes
  • Easily negotiates stairs, climbs on play equipment, learns athletic skills, and rides a bike
  • Can execute daily living skills such as pouring without spilling, spreading a sandwich, dressing self correctly
  • Using the correct sequence of strokes to form manuscript or cursive letters
  • Eye-hand coordination for drawing, assembling art project, and handwriting
  • Directional stability for top/bottom and left/right tracking
  • Copy from board accurately
  • Visual “dyslexia”—confused when viewing visual symbols, poor visual discrimination, reversals/inversions/ transpositions due to poor directionality, may not recognise the shape or form of a word that has been seen many times before, i.e., “word-blind”
  • Spelling—poor visual memory for the non-phonetic elements of words

Sally Ingalls, Ph.D., 1990 Used with permission

Problems with verbal short-term memory are also common among dyslexic individuals because such memory requires the use of phonological skills. Thus, poor readers may have problems recalling letters, digits, words, or phrases in exact sequence. When problems with verbal short-term memory occur together with poor listening comprehension, it is obvious that the individual will have particular difficulty following verbal directions, especially if he is in a noisy setting.


Associated Problems: In addition to these difficulties, children with reading disorders have problems in a variety of other areas. They include the following:

Other Academic Problems: Deficits in auditory-verbal abilities have a marked impact on other academic skills, such as spelling, writing, and even arithmetic. In fact, among poor readers, spelling is generally even more impaired than reading ability. As Dr. Pennington points out, we do not simply memorise the spelling of words. If we did, each new word we encountered would be completely novel and we could not use information from words already known. Instead, we rely on our knowledge of phonics to learn and remember the spelling of new words.*

Poor auditory-verbal abilities can also have an adverse effect on the production of written material since the same coding processes are used in both reading and writing. However, writing also requires additional skills. In fact, since writing involves both automatic and conceptual verbal skills as well as motor skills, it is the most complex academic process we must master. Not only must we remember the phonological code; we must also think of the words to express what we want to say, organize them according to the rules of grammar and syntax, and then go through the mechanical process of putting them on paper — paying attention, of course, to the size, shape, and spacing of the letters, punctuation, and so on. The wonder is not that so many children have difficulty with written expression but that any of us ever learn to write at all!

Many dyslexic children also have difficulty with mathematics. They may, for example, have difficulty memorising basic math facts and remembering sequences of steps for computation (for example, long division). They may mislabel numbers, confusing 16 with 60, and they often have difficulty understanding word problems.

Speech and Language Problems

Among children with reading disorders, it is common to find a history of early developmental speech and language disorders. In addition to delayed speech, problems include difficulty naming objects and colours and remembering one’s address, telephone number, and the like. Problems with word retrieval (finding the right word to express one’s meaning) are also common.

There is also a well-documented association between reading disorders and developmental articulation disorders. In an articulation disorder, mispronunciations occur because individual sounds are substituted, omitted, or distorted. While some cases of articulation disorders are caused by faulty hearing or structural defects in the mouth or tongue, difficulties with phonology appear to be the source of the problem for many individuals.

On the other hand, stuttering and other disorders of speech fluency are not associated with reading disorders. In these disorders, it is the rhythm of speech that is disturbed, not the pronunciation of speech sounds.

Attention Deficit Hyperactivity Disorder (ADHD)

There is considerable overlap between learning and attention problems. We noted that when we examine a group of ADHD children, we find that approximately 19 to 26 percent also have learning disabilities. Conversely, when we begin with a group of children who have been diagnosed as dyslexic, we find that about one third also have ADHD.

What are we to make of this relationship? Researchers who have studied the question have come up with at least three theories about the link between ADHD and learning disabilities: 1) ADHD children have difficulty with academic achievement because they are inattentive and impulsive; 2) learning-disabled children “turn off and tune out” in the classroom because the work is so difficult for them; and 3) ADHD and dyslexia share a common genetic cause, so a child who inherits one disorder will also inherit the other.

After years of heated debate, it appears that all three theories have merit. In some cases, ADHD and dyslexia may occur together because of a shared genetic cause.7 In other cases, even when there is no common genetic cause, there is a reciprocal relationship between ADHD and learning difficulties; that is, inattentive behaviour leads to learning problems, and learning problems make it likely that the child will often be inattentive and off- task.8

Allergic Disorders

Many investigators have reported a high incidence of allergies in dyslexic children. This observation has given rise to one of the most common myths concerning learning disabilities.

Myth: Learning disabilities are caused by allergies.

Fact: There is no evidence that treatment of allergies helps learning problems.

As we have explained elsewhere, simply knowing that two things are related does not explain the direction of the relationship; that is, whether A causes B, B causes A, or both A and B are due to a third cause. In the case of the relationship between allergies and learning disorders, many people have interpreted this relationship to mean that allergies cause learning disabilities, and have devised treatment programs designed to remediate learning problems by treating suspected allergies.

An alternative—and equally plausible—explanation of the relationship between allergies and learning disabilities is that both are caused by a third factor. In fact, recent evidence concerning genetics suggests that this is indeed the case, at least in certain types of learning disorders. At the University of Colorado, Dr. John DeFries and his colleagues have identified a subtype of hereditary dyslexia which is linked to chromosome 6. Since this chromosome contains many genes that affect the immune system, Dr DeFries believes that there may be a gene in this region which affects both reading and immune functions.9 If this is the case, treating one set of symptoms (allergies) would not be expected to have any effect on the second set of symptoms (reading problems).

Emotional Disorders

A link between learning disabilities and emotional problems has been identified by several investigators. Some, for example, have found depressive symptoms in a third or more of the learning-disabled children they studied, 10 a figure which is obviously much higher than in the general population. The most current research also suggests that different subtypes of learning disorders are associated with different kinds of emotional/psychological problems. Specifically, language-based learning disabilities appear to be related to the so-called “externalizing disorders” of ADHD and Conduct Disorder, while nonverbal learning disabilities seem to have a stronger relationship with depression and anxiety disorders, the “internalising disorders.”

From a common sense perspective, the connection between learning disabilities and psychological problems seems obvious. After years of struggling —and failing—to perform in school, it would be quite surprising if the learning- disabled youngster were not somewhat depressed and demoralized. It seems equally apparent that a child who suffers from crippling depression and/or anxiety will have little energy available for learning.

Here again, however, we must be cautious about a chicken-and-egg approach in attributing the cause to one set of problems or the other. Much time and energy may be wasted if we focus on trying to determine whether a child can’t read because he is distracted by fears and worries or whether he is (justifiably) anxious because he can’t perform in school. Instead, we would do far better to simply recognize the existence of both emotional and learning problems and develop a treatment plan that addresses both.

Visual-Motor Learning Disabilities

This group of learning disabilities includes specific problems with arithmetic and handwriting which may occur with or without associated reading disabilities. Also included under the heading of visual-motor learning disabilities are deficits in social awareness and social judgment. Since these problems are not language-based in nature, they are also referred to as “nonverbal learning disabilities.”

Nonverbal learning disabilities occur much less frequently than language-based learning disabilities. Studies show that among children referred to learning disability clinics, only about 1 to 10 percent have nonverbal learning disabilities.

Nonverbal learning disabilities are sometimes called “right-hemisphere learning disabilities.” Since there are many complex connections between the right and left hemispheres (sides) of the brain, it would be an oversimplification to speak of one hemisphere of the brain as if it existed in complete isolation from the other. In general, however, we can say that the brain is organised in such a way that the left hemisphere is specialised for language, while the right hemisphere is specialized for processing nonverbal information. This includes spatial awareness, recognition and organization of visual patterns, and coordination of visual information with motor processes (visual-motor integration). The right hemisphere is also specialized for detecting differences between tones, so it has major responsibility for perceiving melody in music as well as the melodic pattern of spoken language (variations in tone and stress).

As we might expect, children who have right-hemisphere learning disabilities are often poorly coordinated in terms of both fine and gross motor skills. They may have difficulty learning to ride a bike and mastering other athletic skills. At a preschool level, they have problems with cut-and-paste activities, using crayons and markers, and learning to tie their shoes. They are also poor at assembling puzzles and building with construction toys. As they grow older, we see weaknesses in nonverbal problem solving and concept formation. Although these children may have very well developed rote verbal memory, they have a great deal of difficulty adapting to novel or complex situations.

Specific Deficits

As noted, these children have difficulty in the areas of handwriting and arithmetic, often without associated reading problems. They also have problems with social awareness and judgment.


Eye-hand coordination is an obviously important factor in handwriting. The child with a right- hemisphere learning disability may have difficulty remembering the shapes of letters (poor visual memory) and using the correct sequence of strokes to form letters. He may also have an awkward pencil grip. Letters are poorly spaced and of different sizes, and writing is quite slow and laboured. Copying accurately from the board is also likely to be particularly difficult for this youngster.


The specific difficulties with arithmetic found in children with right-hemisphere learning disabilities lie in understanding the fundamental concepts of mathematics. In this regard, their problems with math are different from those seen in dyslexic children, who struggle to memorize math facts and understand word problems. Consequently, the kinds of arithmetic errors made by dyslexic children and those with specific arithmetic disability are quite different. Dyslexia children may make mistakes because they reverse numbers or forget basic math facts and have to count on their fingers, but they usually grasp the basic principles and subroutines needed to solve the problem. In contrast, the child with a specific math disability has difficulty understanding what approach is required to solve a particular problem and what a reasonable answer might be.

Social Skills Deficits

While there are certainly children with specific math and handwriting disabilities who do not have social difficulties, the problems overlap so frequently that social skills disabilities are considered a component of nonverbal learning disabilities.

The problems in social interaction seen in individuals with right-hemisphere learning disabilities seem to reflect the difficulty in perceiving nonverbal cues in communication. Their visual-spatial-organizational deficits put them at a disadvantage in recognising faces and interpreting gestures, body posture, and facial expressions. They also have difficulty perceiving vocal cues in spoken languages, such as rate, tone, and emphasis.

These deficits place the child at a real social disadvantage because nonverbal signals and cues are so important in communication. For example, in an average conversation between two people, the verbal components carry less than 35 percent of the social meaning of the situation, while more than 65 percent is conveyed through nonverbal messages. Nonverbal behaviour is especially important in communicating feelings, emotions, and liking or disliking. In fact, it is estimated that of the total liking or affection we communicate to another person, only 7 percent is actually communicated through words. Voice cues like pitch and volume carry 38 percent; facial expression and eye contact, 55 percent.

Nonverbal cues also function like traffic signals to regulate conversational beginnings and endings, turn-takings in conversation, and changes in the subject. Just as an automobile driver who doesn’t respond to traffic signals will be considered a poor driver, so to the person who can’t “read” nonverbal cues will be seen as rude, boorish, and are socially inept.

Emotional Problems

As we mentioned earlier in this article, children with nonverbal learning disabilities seem particularly prone to developing so-called “internalizing disorders,” characterised by depression and/or anxiety. In that section, we also alluded to questions concerning the direction of this relationship; that is, do learning disabilities cause emotional problems or do emotional problems prevent the child from learning appropriately, thereby causing learning disabilities?

A third possibility, of course, is that some other factor, such as an underlying problem within the central nervous system, actually lies at the root of both kinds of problems. Dr. Byron Rourke, an authority on nonverbal learning disabilities, believes that the evidence is strongest in favour of this last notion and thinks that a disturbance in the right hemisphere can account for both sets of problems.12

This reminds us once again that we should not limit ourselves to a naive either-or approach when confronted with a youngster who appears to suffer from both learning and emotional problems. Instead, we should direct our resources toward accurate diagnosis and appropriate remediation of both conditions.

What Causes Learning Disabilities?

Since language-based and nonverbal learning disabilities appear to have different causes, especially in regard to the site of the problem within the brain, we will consider each category separately.

Language-Based Learning Disabilities

Genetic Factors

Almost from the time dyslexia was first described, early in this century, heredity has been known to play an important role. Heredity probably accounts for the majority of language-based learning disabilities, and when we look at family members of individuals with dyslexia, we usually find that 35 to 40 percent of their closest relatives have similar difficulties. In some families, dyslexia is linked to genetic markers on chromosome 15, while in others, chromosome 6 appears to be involved.

Environmental Factors

We know less about environmental causes of dyslexia than we do about genetic factors. As is the case with ADHD, there is a link between learning disorders and maternal alcohol abuse during pregnancy. Mothers who abuse “crack” cocaine give birth to babies who suffer from a variety of problems, including ADHD and learning disabilities. The link with maternal smoking is less clear: mothers who smoke give birth to smaller babies, but since a woman who smokes during pregnancy often abuse alcohol as well, it may be that alcohol is the critical factor in the relationship.

Some researchers have also implicated environmental toxins and pollutants, but this link is also difficult to confirm. Others have reported a relationship between reading disorders and both large family size and low socioeconomic status.15 In large families, it is more difficult for all children to receive optimal amounts of attention and stimulation; in some impoverished families, parents do not spend much time reading to their children or playing language games with them.

Brain Mechanisms in Dyslexia

Researchers generally agree that dyslexia involves dysfunction in the left hemisphere of the brain, the hemisphere which is specialized for language. Using brain-imaging techniques like PET scans, scientists have consistently found differences in left-hemisphere functioning in dyslexics, even with tasks that do not involve reading.

One area, in particular, known as the “planum temporale,” has been the focus of recent promising research. In most people, this area is asymmetrical, with the area on the left side of the brain larger than that on the right side. In dyslexics, however, researchers have found that these areas are equal in size (symmetrical) or that the right side is actually larger than the left. At Harvard University Medical School, for example, Dr Albert Galaburda and his colleagues have performed autopsies on the brains of ten dyslexic individuals and have found this pattern in every case.16 Their findings have also been supported by the results of studies in which magnetic resonance imaging (MRI) techniques have been used to compare the brains of dyslexics and non-dyslexic individuals.

Neuroscientists are not certain what causes this difference. One possibility is that during early development of the brain, some cells migrate to the wrong areas. Other possibilities include overproduction of brain cells in certain areas and failure of the system to “prune” (remove) excess brain cells. According to Dr. Galaburda, factors that control the production of brain cells are likely to be mainly genetic, while “pruning” depends on environmental influences as well as genetic factors. This would account for the fact that some cases of dyslexia appear to be hereditary in origin, while environmental factors may be important in others.

Visual-Motor Learning Disabilities

Genetic Factors

No family studies of these disorders have been done, so we have very little information about the role of heredity in the nonverbal learning disabilities. However, we do know that two specific genetic syndromes, Turner syndrome and Fragile X syndrome in females, are associated with specific problems in arithmetic, handwriting, and social skills.18

Environmental Factors

In Boston, the eminent neurologist Marcel Mesulam studied fourteen children with nonverbal learning disabilities and found evidence of brain damage in nine of them.19 At the University of Windsor, Dr Byron Rourke and his associates found nonverbal learning disabilities in children who suffered moderate to severe head injuries; children who had received radiation treatment of the head; children who had been unsuccessfully treated for hydrocephalus; and children who had significant amounts of tissue removed from the right hemisphere. Since all of these conditions involve the destruction of white matter (the long, myelinated fibers in the brain) in the right hemisphere, Dr. Rourke believes that nonverbal learning disabilities are caused by early damage to white matter in the right hemisphere.

How are Learning Disabilities Diagnosed?

The process by which learning disabilities are diagnosed stems directly from the specific questions the evaluator is asked to address. If, for example, the question is “Does this child read as well as expected for his age and grade?” the evaluator can use standardised tests which enable him to derive age and grade scores for the child’s level of achievement. Tests like the Woodcock-Johnson Psychoeducational Battery20 and the Peabody Individual Achievement Test are reliable and efficient tools for this purpose. These tests assess specific academic skills such as word and sentence reading, reading comprehension, vocabulary, spelling, math knowledge, and math application. Because these tests are administered on an individual basis, they are often very helpful with inattentive or learning-disabled children to accurately assess their levels of achievement. Often individual testing avoids many of the problems encountered by inattentive and learning-disabled children during group testing. Individual assessment also allows the evaluator to take additional time to build motivation and make certain that the best possible performance is being obtained. Tests such as these are well standardised. Standardisation refers to the process by which a test is administered to thousands of children across the country in an effort to provide a sample of children which recognises the contribution of differences such as age, sex, educational experience, socioeconomic status, and even ethnic background.

But there are additional steps which go beyond simply ascertaining whether the child reads at a level commensurate with his age and grade level. For example, we might also ask “Does this child read as well as would be expected on the basis of his level of general intelligence?” This question is usually asked when an administrative decision must be made about the child’s eligibility to receive special services through the public school system. To answer this question, the evaluator uses a standardized intelligence test (“IQ test”) such as the Wechsler Intelligence Scale for Children or the cognitive component of the Woodcock-Johnson Psychoeducational Battery. Such tests must be administered on an individual basis by someone who has been specifically trained to administer them and to score and interpret the results. They are somewhat costly to administer, therefore, and school systems are generally reluctant to offer them unless there is a good reason to suspect a real discrepancy between a child’s intelligence and his academic achievement.

There is still another level of assessment, which involves identifying the particular skill deficits and areas of weakness which underlie a child’s learning problems. To address this issue, evaluators use a variety of psychological and neuropsychological tests, such as the Halstead-Reitan Battery for Children or the Luria Nebraska Child and Adolescent Test Battery. In addition, they observe the child as he works with academic tasks so that they can make qualitative judgments about his performance. Thus, in addition to obtaining a child’s age and grade scores in reading, for example, the evaluator actually listens to the child read in order to pinpoint specific strengths and weaknesses.

This information is then combined with other information about the child’s behaviour, attention, motivation, motor skills, speech and language abilities, and so on, to arrive at a comprehensive understanding of the child’s functioning. Ideally, such a comprehensive assessment should lead logically to specific intervention strategies to remedy the problems and improve the child’s ability to achieve.

(This is Chapter 2 of the author’s highly acclaimed book, Attention Deficit Disorder, which deals with learning disabilities, published with his kind permission.)

©Prof. Ashoka Jahnavi Prasad

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