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A B
C D E
F G H
I J K
L M N
O P Q
R S T
U V W
X Y Z
Deaf
A hearing loss so severe that speech cannot be understood aurally, even with a
hearing aid; some sounds may still be perceived.
Decibel (dB)
The unit of measure for the relative intensity of sound on a scale beginning at
zero; zero dB refers to the faintest sound a person with normal hearing can
detect.
Declassification
The process in which a disabled child is no longer considered in need of special
education services. This requires a meeting of the CSE and can be requested by
the parent, school, or child if over the age of eighteen.
Decoding
The process of deriving meaning from written symbols.
Defense Mechanisms
The unconscious means by which individuals protect themselves against impulses
or emotions that are uncomfortable or threatening.
Deficit
A level of performance that is less than expected for a child.
Deinstitutionalization
The social movement to transfer individuals with disabilities, especially
persons with mental retardation, from large institutions to smaller,
community-based settings.
Delusion
A groundless, irrational belief or thought, usually of grandeur or of
persecution; generally a characteristic of paranoia.
Dendrites
The connective tissue that connects one neuron to another.
Denial
A defense mechanism in which the individual refuses to admit the reality of some
unpleasant event, situation, or emotion.
Departmentalized Curriculum
An approach in which subject areas in schools are taught by different
departments or groups of teachers, resulting in the need to change classes and
teachers for each subject.
Depersonalization
A nonspecific syndrome in which the individual senses a loss of personal
identity, that he/she is different, strange, or not real.
Desensitization
A technique used in reinforcement theory in which there is a weakening of a
response, usually an emotional response.
Developmental Lag
A delay in some aspect of physical or mental development.
Dexedrine
One of several stimulant drugs often given to modify hyperactivity in children.
Diabetic Retinopathy
Visual impairment caused by hemorrhages on the retina and other disorders of
blood circulation in people with diabetes.
Diagnosis
The specific disorder(s) identified as a result of evaluation.
Diagnostic and Statistical Manual of Mental Disorders (4th ed.) (DSM-IV)
A classification system published by the American Psychiatric Association for
identifying various kinds of disorders in children.
Dialect
A variety within a specific language arising from a divergence in pronunciation,
word choice, word order, or inflection.
Differential Reinforcement of Other Behavior (DRO)
A procedure in which any behavior except the targeted inappropriate response is
reinforced; typically, this results in a reduction of the inappropriate
behavior.
Diplegia
Paralysis of corresponding parts on both sides of the body.
Direct Instruction
A teacher-led instructional procedure that provides students with specific
instructions on a task, teacher-led practice, independent practice, and
immediate corrective feedback.
Directionality
The ability to know right from left, up from down, forward from backward, and
direction and orientation.
Disability
Condition characterized by functional limitations that impede typical
development as the result of a physical or sensory impairment or difficulty in
learning or social adjustment.
Discrepancy
The concept that students with learning disabilities have abnormal patterns of
development across domains, resulting in significant differences between
measures of different types of abilities and skills; see Splinter Skills.
Discrepancy Criteria
An aspect of the legal definition of learning disabilities that states that such
students must demonstrate a substantial difference between their anticipated
achievement, as indicated by intellectual ability, and their actual achievement;
this discrepancy is referred to as the Ability-Achievement Discrepancy.
Discrimination
The process of detecting differences between and/or among stimuli.
Disinhibition
Lack of restraint in responding to a situation.
Displacement
The disguising of the goal or intention of a motive by substituting another in
its place.
Disruptive Behavior
Behavior that disrupts the instruction of other students in the classroom.
Distractibility
The shifting of attention from the task at hand to sounds, sights, and other
stimuli that normally occur in the environment.
Dolch Sight Words
A list of 220 words categorized by grade level that represent 50% to 75% of the
words used in children’s school books.
Double Hemiplegia
Paralysis that involves both sides of the body, with one side being more greatly
affected.
Down Syndrome
A chromosomal anomaly that often causes moderate to severe mental retardation,
along with certain physical characteristics such as a large tongue, heart
problems, poor muscle tone, and a broad, flat bridge of the nose.
Duchenne Muscular Dystrophy
The most common form of muscular dystrophy, a group of long-term diseases that
progressively weaken and waste away the body’s muscles.
Due Process
The application of law so as to ensure that an individual’s rights are
protected. In reference to special education, due process refers to the premise
that parents have the right to request a full review of any educational program
developed for their child; designed to protect an individual’s constitutional
rights under the Fifth Amendment to the Constitution.
Duration of Behavior
Measure of how long a person engages in a given activity.
Dynamic Assessment
An assessment practice that is related to the task as well as to the thought
processes involved in performing the task.
Dysarthria
A disorder of the speech muscles that affects the ability to pronounce words.
Dyscalculia
Difficulty in understanding or using mathematical symbols or functions. A child
with dyscalculia may be able to read and write but have difficulty in performing
mathematical calculations.
Dysfluency
Difficulty in the production of fluent speech; normally associated with
stuttering.
Dysfunction
Any disturbance or impairment in the normal functioning of an organ or body
part.
Dysgraphia
Difficulty in producing legible handwriting with age-appropriate speed.
Dyslexia
A specific language-based disorder characterized by difficulties in single word
decoding, usually reflecting insufficient phonological processing. These
difficulties, which are not the result of generalized developmental disability
or sensory impairment, are often unexpected in relation to age and other
cognitive and academic abilities and severely impair the individual’s ability to
read.
Dysnomia
Difficulty in remembering names or recalling appropriate words to use in a given
context.
Dysorthographia
A learning disability that affects a child’s ability to spell.
Dyspraxia
Difficulty in performing fine motor tasks.
*See
Reference Information
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