Official definitions
The term "learning disability" was apparently first used and defined by Dr. Samuel Kirk (1962, cited in Streissguth, Bookstein, Sampson, & Barr, 1993, p.144). The term referred to a discrepancy between a child’s apparent capacity to learn and his or her level of achievement. A review of the LD classifications for 49 of 50 states revealed that 28 of the states included IQ/Achievement discrepancy criteria in their LD guidelines (Ibid., citing Frankenberger & Harper, 1987). However, the National Joint Committee for Learning Disabilities (NJCLD) (1981; 1985) preferred a slightly different definition:
The Individuals with Disabilities Education Act (United States) defines a learning disability this way:
The Learning Disabilities Association of Ontario (Canada) defines LDs this way:
Contrast with other conditions
People with an IQ lower than 70 are usually characterized as having mental retardation (MR), mental deficiency, or cognitive impairment and are not included under most definitions of learning disabilities, because their learning difficulties are related directly to their low IQ scores. In contrast, learning disabled individuals have the potential to learn as much as other people of average intelligence, but something is preventing them from reaching that potential.
Attention-deficit hyperactivity disorder (ADHD) is often studied in connection with learning disabilities, but it is not actually included in the standard definitions of learning disabilities. An individual with ADHD may struggle with learning, but he or she can often learn adequately once successfully treated for the ADHD. A person can have ADHD but not learning disabilities or have learning disabilities without having ADHD. The conditions can co-occur (see Comorbidity). In order to understand the difference, imagine that someone with a learning disability is affected in only one or a few areas. However, people with ADHD are often affected in all areas.
Research is beginning to make a case for ADHD's being included in the definition of LDs, since it is being shown to have a strong impact on "executive functions" required for learning (planning, organization, etc). This has not as yet affected any official definitions.
Areas of perception involved
Learning disabilities involve many areas of perception, which include:
- Visual or Auditory Discrimination perceiving differences in either sights or sounds
- filling in missing parts of sights or sounds
- focusing on an object and disregarding its background
- putting what is seen or heard in the right order
- relating what is heard to other things, including definitions of words and meanings of sentences
- laterality (above vs. below, between, inside vs. outside) and one's position in space
- processing time intervals in the range of milliseconds, critical to the development of speech processing
- Processing nonverbal cues in social interactions
Terminology and classification
Various terms are used to describe particular learning disabilities. A person can have one of them or more than one of them.
Some of them are as follows (codes provided are ICD-10 and DSM-IV, respectively.)
Various theories have been posited for the cause or causes of learning disabilities. Causes for the neurological impairments may involve:
Learning disabilities are a life-long condition, and are not "curable". Effective treatment involves multi-modal and appropriately tailored teaching and compensatory strategies/tools such as
- (F80.0-F80.2/315.31) Dysphasia/aphasia - Speech and language disorders difficulty producing speech sounds (articulation disorder)
- difficulty putting ideas into spoken form (expressive disorder)
- difficulty perceiving or understanding what other people say (receptive disorder)
- difficulty in phonetic mapping, where sufferers have difficulty with matching various orthographic representations to specific sounds
- Some claim that dyslexia involves a difficulty with spatial orientation, which is stereotyped in the confusion of the letters b and d, as well as other pairs. In its most severe form, b, d, p and q, all distinguished primarily by orientation in handwriting, look identical to the dyslexic. However, there is no scientific evidence that dyslexia, or other learning difficulties, are related to vision or can be alleviated with visual exercises or colored glasses.
- Some claim that dyslexia involves a difficulty with sequential ordering, such that a person can see a combination of letters but not perceive them in the correct order. However, as with spatial orientation, there is no scientific evidence that dyslexia involves a visual problem.
- defects or errors in brain structure
- drug abuse
- poor nutrition
- parents' genes
- lack of parental involvement during early development stages in the infant
- lack of communication between various parts of the brain
- incorrect quantities of various neurotransmitters, or problems in the brain's use of these transmitters
- special seating assignments
- alternative or modified assignments
- modified testing procedures
- electronic spellers and dictionaries
- word processors
- talking calculators
- audio books
- Text-to-Speech (TTS) Software
- note-takers
- readers
- proofreader