What are learning disabilities?

Causes and Symptoms

An understanding of learning disabilities must begin with the knowledge that the definition, diagnosis, and treatment of these disorders have historically generated considerable disagreement and controversy. This is primarily attributable to the fact that people with learning disabilities are a highly diverse group of individuals with a wide variety of characteristics. Consequently, differences of opinion among professionals remain to such an extent that presenting a single universally accepted definition of learning disabilities is not possible. Definitional differences most frequently center on the relative emphases that alternative groups place on characteristics of these disorders. For example, experts in medical fields typically describe these disorders from a disease model and view them primarily as neurological dysfunctions. Conversely, educators usually place more emphasis on the academic problems that result from learning disabilities. Despite these differences, the most commonly accepted definitions, those developed by the United States Office of Education in 1977, the Board of the Association for Children and Adults with Learning Disabilities in 1985, and the National Joint Committee for Learning Disabilities in 1981, do include some areas of commonality.

Difficulty in academic functioning is included in the three definitions, and virtually all descriptions of learning disabilities include this characteristic. Academic deficits may be in one or more formal scholastic subjects, such as reading or mathematics. Often the deficits will involve a component skill of the academic area, such as problems with comprehension or word knowledge in reading or difficulty in calculating or applying arithmetical reasoning in mathematics. The academic difficulty may also be associated with more basic skills of learning that influence functioning across academic areas; these may involve deficits in listening, speaking, and thinking. Dyslexia, a term for reading problems, is the most common academic problem associated with learning disabilities. Because reading skills are required in most academic activities to some degree, many view dyslexia as the most serious form of learning disability.

The presumption of a neurological dysfunction as the cause of these disorders is included, either directly or indirectly, in each of the three definitions. Despite this presumption, unless an individual has a known history of brain trauma, the neurological basis for learning disabilities will not be identified in most cases because current assessment technology does not allow for such precise diagnoses. Rather, at least minimal neurological dysfunction is simply assumed to be present in anyone who exhibits characteristics of a learning disorder.

The three definitions all state that individuals with learning disabilities experience learning problems despite possessing normal intelligence. This condition is referred to as a discrepancy between achievement and ability or potential.

Finally, each of the three definitions incorporates the idea that learning disabilities cannot be attributed to another condition such as vision or hearing problems, emotional or psychiatric disturbance, or social, cultural, or educational disadvantage. Consequently, these conditions must be excluded as primary contributors to academic difficulties.

A number of causes of learning disabilities have been proposed, with none being universally accepted. Some of the most plausible causal theories include neurological deficits, genetic and hereditary influences, and exposure to toxins during fetal gestation or early childhood.

Evidence to support the assumption of a link between neurological dysfunction and learning disabilities has been provided by studies using sophisticated brain imaging techniques such as positron emission tomography (PET) and computed tomography (CT) scanning and magnetic resonance imaging (MRI). Studies using these techniques have, among other findings, indicated subtle abnormalities in the structure and electrical activity in the brains of individuals with learning disabilities. The use of such techniques has typically been confined to research; however, the continuing advancement of brain imaging technology holds promise not only in contributing greater understanding of the nature and causes of learning disabilities but also in treating the disorder.

Genetic and hereditary influences also have been proposed as causes. Supportive evidence comes from research indicating that identical twins are more likely to be concordant for learning disabilities than fraternal twins and that these disorders are more common in certain families.

A genetic cause of learning disabilities may be associated with extra X or Y chromosomes in certain individuals. The type and degree of impairment associated with these conditions vary according to many genetic and environmental factors, but they can involve problems with language development, visual perception, memory, and problem solving. Despite evidence to link chromosome abnormalities to those with learning disabilities, most experts agree that such genetic conditions account for only a portion of these individuals.

Exposure to toxins or poisons during fetal gestation and early childhood can also cause learning disabilities. During pregnancy nearly all substances the mother takes in are transferred to the fetus. Research has shown that mothers who smoke, drink alcohol, or use certain drugs or medications during pregnancy are more likely to have children with developmental problems, including learning disabilities. Yet not all children exposed to toxins during gestation will have such problems, and the consequences of exposure will vary according to the period when it occurred, the amount of toxin introduced, and the general health and nutrition of the mother and fetus.

Though not precisely involving toxins, two other conditions associated with gestation and childbirth have been linked to learning disabilities. The first, anoxia, or oxygen deprivation, occurring for a critical period of time during the birthing process has been tied to both developmental and learning disabilities. The second, and more speculative, involves exposure of the fetus to an abnormally large amount of testosterone during gestation. Differences in brain development are proposed to result from the exposure, causing learning disorders and other abnormalities. Known as the embryological theory, it may account for the large number of males with these disabilities, since they have greater amounts of testosterone than females.

The exposure of the immature brain during early childhood to insecticides, household cleaning fluids, alcohol, narcotics, and carbon monoxide, among other toxic substances, may also cause learning disabilities. Lead poisoning resulting from ingesting lead from paint, plaster, and other sources has been found in epidemic numbers in some sections of the United States. Lead poisoning can damage the brain and cause learning disabilities as well as a number of other serious problems.

The number and variety of proposed causes not only reflect differences in experts’ training and consequent perspectives but also suggest the likelihood that these disorders can be caused by multiple conditions. This diversity of views also carries to methods for assessing and providing treatment and services to individuals with learning disabilities.

Treatment and Therapy

In 1975, the US Congress adopted the Education for All Handicapped Children Act, which, along with other requirements, mandated that students with disabilities, including those with learning disabilities, be identified and provided appropriate educational services. Since that time, much effort has been devoted to developing adequate assessment practices for diagnosis and effective treatment strategies.

In the school setting, assessment of students suspected of having learning disabilities is conducted by a variety of professionals, including teachers specially trained in assessing learning disabilities, school nurses, classroom teachers, school psychologists, and school administrators. Collectively, these professionals are known as a multidisciplinary team. An additional requirement of this educational legislation is that parents must be given the opportunity to participate in the assessment process. Professionals outside the school setting, such as clinical psychologists and independent educational specialists, also conduct assessments to identify learning disabilities.

Because the definition of learning disabilities in the 1975 act includes a discrepancy between achievement and ability as a characteristic of the disorder, students suspected of having learning disabilities are usually administered a variety of formal and informal tests. Standardized tests of intelligence, such as the fourth edition of the Wechsler Intelligence Scale for Children, are administered to determine ability. Standardized tests of academic achievement, such as the Woodcock-Johnson Tests of Achievement and Cognitive Abilities and the Wide Range Achievement Test, also are administered to determine levels of academic skill. Sometimes a child may be asked to take more than one of each kind of test, as a multi-test battery is considered to produce more valid results.

Whether a discrepancy between ability and achievement exists to such a degree as to warrant diagnosis of a learning disability is determined by various formulas comparing the scores derived from the intelligence and achievement tests. The precise methods and criteria used to determine a discrepancy vary according to differences among state regulations and school district practices. Consequently, a student diagnosed with a learning disability in one part of the United States may not be viewed as such in another area using different diagnostic criteria. This possibility has been raised in criticism of the use of the discrepancy criteria to identify these disorders. Other criticisms of the method include the use of intelligence quotient (IQ) scores (which are not as stable or accurate as many assume), the inconsistency of students’ scores when using alternative achievement tests, and the lack of correspondence between what students are taught and what is tested on achievement tests.

In partial consequence of these and other problems with standardized tests, alternative informal assessment methods have been developed. One such method that is frequently employed is termed curriculum-based assessment (CBA). The CBA method uses materials and tasks taken directly from students’ classroom curriculum. For example, in reading, CBA might involve determining the rate of words read per minute from a student’s textbook. CBA has been demonstrated to be effective in distinguishing among some students with learning disabilities, those with other academic difficulties, and those without learning problems. Nevertheless, many professionals remain skeptical of CBA as a valid alternative to traditional standardized tests.

Other assessment techniques include vision and hearing tests, measures of language development, and tests examining motor coordination and sensory perception and processing. Observations and analyses of the classroom environment may also be conducted to determine how instructional practices and a student’s behavior contribute to learning difficulties.

Based on the information gathered by the multidisciplinary team, a decision is made regarding the diagnosis of a learning disability. If a student is identified with one of these disorders, the team then develops an individual education plan to address identified educational needs. An important guideline in developing the plan is that students with these disorders should be educated to the greatest extent possible with their peers, while still being provided with appropriate services. Considerable debate has occurred regarding how best to adhere to this guideline.

Programs for students with learning disabilities typically are implemented in self-contained classrooms, resource rooms, or regular classrooms. Self-contained classrooms usually contain ten to twenty students and one or more special education teachers specially trained to work with these disorders. Typically, these classrooms focus on teaching fundamental skills in basic academic subjects such as reading, writing, and mathematics. Depending on the teacher’s training, efforts may also be directed toward developing perceptual, language, or social skills. Students in these programs usually spend some portion of their day with their peers in regular education meetings, but the majority of the day is spent in the self-contained classroom.

The popularity of self-contained classrooms has decreased significantly since the 1960s, when they were the primary setting in which students with learning disabilities were educated. This decrease is largely attributable to the stigmatizing effects of placing students in special settings and the lack of clear evidence to support the effectiveness of this approach.

Students receiving services in resource rooms typically spend a portion of their day in a class where they receive instruction and assistance from specially trained teachers. Students often spend one or two periods in the resource room with a small group of other students who may have similar learning problems or function at a comparable academic level. In the elementary grades, resource rooms usually focus on developing basic academic skills, whereas at the secondary level time is more typically spent in assisting students with their assignments from regular education classes.

Resource room programs are viewed as less restrictive than self-contained classrooms; however, they too have been criticized for segregating children with learning problems. Other criticisms center on scheduling difficulties inherent in the program and the potential for inconsistent instructional approaches and confusion over teaching responsibilities between the regular classroom and resource room teachers. Research on the effectiveness of resource room programs also has been mixed; nevertheless, they are found in most public schools across the United States.

Increasing numbers of students with learning disabilities have their individual education plans implemented exclusively in a regular classroom, a practice known as mainstreaming. In most schools where such programs exist, teachers are given assistance by a consulting teacher with expertise in learning disabilities. Supporters of this approach point to the lack of stigma associated with segregating students and the absence of definitive research supporting other service models. Detractors are concerned about the potential for inadequate support and training for the classroom teacher, resulting in students receiving insufficient services. The movement to provide services to students with learning disabilities in regular education settings, termed the Regular Education Initiative, has stirred much debate among professionals and parents.

No one specific method of teaching these students has been demonstrated to be superior to others. A variety of strategies have been developed, including perceptual training, multisensory teaching, modality matching, and direct instruction. Advocates of perceptual training believe that academic problems stem from underlying deficits in perceptual skills. They use various techniques aimed at developing perceptual abilities before trying to remedy or teach specific academic skills. Multisensory teaching involves presenting information to students through several senses. Instruction using this method may be conducted using tactile, auditory, visual, and kinesthetic exercises. Instruction involving modality matching begins with identifying the best learning style for a student, such as visual or auditory processing. Learning tasks are then presented via that mode. Direct instruction is based on the principles of behavioral psychology. The method involves developing precise educational goals, focusing on teaching the exact skill of concern, and providing frequent opportunities to perform the skill until it is mastered.

With the exception of direct instruction, research has generally failed to demonstrate that these strategies are uniquely effective with students with learning disabilities. Direct instruction, on the other hand, has been demonstrated to be effective but has also been criticized for focusing on isolated skills without dealing with the broader processing problems associated with these disorders. More promisingly, students with learning disabilities appear to benefit from teaching approaches that have been found effective with students without learning problems when instruction is geared to ability level and rate of learning.

Perspective and Prospects

Interest in disorders of learning can be identified throughout the history of medicine. The specific study of learning disabilities, however, can be traced to the efforts of a number of physicians working in the first quarter of the twentieth century who studied the brain and its associated pathology. One such researcher, Kurt Goldstein, identified a number of unusual characteristics, collectively termed perceptual deficits, that were associated with head injury.

Goldstein’s work influenced a number of researchers affiliated with the Wayne County Training School, including Alfred Strauss, Laura Lehtinen, Newell Kephart, and William Cruickshank. These individuals worked with children with learning problems who exhibited many of the characteristics of brain injury identified by Goldstein. Consequently, they presumed that neurological dysfunction, whether it could specifically be identified or not, caused the learning difficulties. They also developed a set of instructional practices involving reduced environmental stimuli and exercises to develop perceptual skills. The work and writings of these individuals through the 1940s, 1950s, and 1960s were highly influential, and many programs for students with learning disabilities were based on their theoretical and instructional principles.

Samuel Orton, working in the 1920s and 1930s, also was influenced by research into brain injury in his conceptualization of children with reading problems. He observed that many of these children were left-handed or ambidextrous, reversed letters or words when reading or writing, and had coordination problems. Consequently, he proposed that reading disabilities resulted from abnormal brain development and an associated mixing of brain functions. Based on the work of Orton and his students, including Anna Gilmore and Bessie Stillman, a variety of teaching strategies were developed that focused on teaching phonics and using multisensory aids. In the 1960s, Elizabeth Slingerland applied Orton’s concepts in the classroom setting, and they have been included in many programs for students with learning disabilities.

A number of other researchers have developed theories for the cause and treatment of learning disabilities. Some of the most influential include Helmer Mykelbust and Samuel Kirk, who emphasized gearing instruction to a student’s strongest learning modality, and Norris Haring, Ogden Lindsley, and Joseph Jenkins, who applied principles of behavioral psychology to teaching.

The work of these and other researchers and educators raised professional and public awareness of learning disabilities and the special needs of individuals with the disorder. Consequently, the number of special education classrooms and programs increased dramatically in public schools across the United States in the 1960s and 1970s. Legislation on both state and federal levels, primarily resulting from litigation by parents to establish the educational rights of their children, also has had a profound impact on the availability of services for those with learning disabilities. The passage of the Education for All Handicapped Children Act in 1975 not only mandated appropriate educational services for students with learning disabilities but also generated funding, interest, and research in the field. The Regular Education Initiative has since prompted increased efforts to identify more effective assessment and treatment strategies and generated debates among professionals and the consumers of these services. Decisions resulting from these continuing debates will have a significant impact on future services for individuals with learning disabilities.

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