Types of
learning disabilities
Learning disabilities can be categorized
either by the type of information processing that is affected or by the
specific difficulties caused by a processing deficit.
Information
processing deficits
Learning disabilities fall into broad
categories based on the four stages of information processing used in
learning: input, integration, storage, and output.
This is the information perceived through
the senses, such as visual and auditory perception. Difficulties with visual
perception can cause problems with recognizing the shape, position and size
of items seen. There can be problems with sequencing, which can relate to
deficits with processing time intervals or temporal perception. Difficulties
with auditory perception can make it difficult to screen out competing
sounds in order to focus on one of them, such as the sound of the teacher's
voice. Some children appear to be unable to process tactile input. For
example, they may seem insensitive to pain or dislike being touched.
This is the stage during which perceived
input is interpreted, categorized, placed in a sequence, or related to
previous learning. Students with problems in these areas may be unable to
tell a story in the correct sequence, unable to memorize sequences of
information such as the days of the week, able to understand a new concept
but be unable to generalize it to other areas of learning, or able to learn
facts but be unable to put the facts together to see the "big picture." A
poor vocabulary may contribute to problems with comprehension.
Problems with memory can occur with
short-term or working memory, or with long-term memory. Most memory
difficulties occur in the area of short-term memory, which can make it
difficult to learn new material without many more repetitions than is usual.
Difficulties with visual memory can impede learning to spell.
Information comes out of the brain either
through words, that is, language output, or through muscle activity, such as
gesturing, writing or drawing. Difficulties with language output can create
problems with spoken language, for example, answering a question on demand,
in which one must retrieve information from storage, organize our thoughts,
and put the thoughts into words before we speak. It can also cause trouble
with written language for the same reasons. Difficulties with motor
abilities can cause problems with gross and fine motor skills. People with
gross motor difficulties may be clumsy, that is, they may be prone to
stumbling, falling, or bumping into things. They may also have trouble
running, climbing, or learning to ride a bicycle. People with fine motor
difficulties may have trouble buttoning shirts, tying shoelaces, or with
handwriting.
Specific
learning disabilities
Deficits in any area of information
processing can manifest in a variety of specific learning disabilities. It
is possible for an individual to have more than one of these difficulties.
This is referred to as comorbidity or co-occurrence of learning
disabilities. In the UK, the term dual diagnosis is often used to
refer to co-occurrence of learning difficulties.
- Reading disability (ICD-10 and DSM-IV
codes: F81.0/315.00)
The most common learning disability. Of all
students with specific learning disabilities, 70%-80% have deficits in
reading. The term "dyslexia" is often used as a synonym for reading
disability; however, many researchers assert that there are different types
of reading disabilities, of which dyslexia is one. A reading disability can
affect any part of the reading process, including difficulty with accurate
and/or fluent word recognition, word decoding, reading rate, prosody (oral
reading with expression), and reading comprehension. Before the term
"dyslexia" came to prominence, this learning disability used to be known as
"word blindness."
Common indicators of reading disability
include difficulty with phonemic awareness -- the ability to break up words
into their component sounds, and difficulty with matching letter
combinations to specific sounds (sound-symbol correspondence).
- Writing disability (ICD-10 and DSM-IV
codes F81.1/315.2)
Speech and language disorders can also be
called Dysphasia/Aphasia (coded F80.0-F80.2/315.31 in ICD-10 and DSM-IV).
Impaired written language ability may
include impairments in handwriting, spelling, organization of ideas, and
composition. The term "dysgraphia" is often used as an overarching term for
all disorders of written expression. Others, such as the International
Dyslexia Association, use the term "dysgraphia" exclusively to refer to
difficulties with handwriting.
- Math disability (ICD-10 and DSM-IV codes
F81.2-3/315.1)
Sometimes called dyscalculia, a math
disability can cause such difficulties as learning math concepts (such as
quantity, place value, and time), difficulty memorizing math facts,
difficulty organizing numbers, and understanding how problems are organized
on the page. Dyscalculics are often referred to as having poor "number
sense".
- Nonverbal learning disability [this
disorder is not listed in the ICD-10]
Nonverbal learning disabilities often
manifest in motor clumsiness, poor visual-spatial skills, problematic social
relationships, difficulty with math, and poor organizational skills. These
individuals often have specific strengths in the verbal domains, including
early speech, large vocabulary, early reading and spelling skills, excellent
rote-memory and auditory retention, and eloquent self-expression.
Sometimes called motor planning, dyspraxia
refers to a variety of difficulties with motor skills. Dyspraxia can cause
difficulty with single step tasks such as combing hair or waving goodbye,
multi-step tasks like brushing teeth or getting dressed, or with
establishing spatial relationships such as being able to accurately position
one object in relation to another.
- Disorders of speaking and listening
Difficulties that often co-occur with
learning disabilities include difficulty with memory, social skills and
executive functions (such as organizational skills and time management).
- Auditory processing disorder
Difficulties processing auditory
information include difficulty comprehending more than one task at a time
and a relatively stronger ability to learn visually. |