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D

Daily Living Activities: Routine maintenance or self-improvement tasks which include eating, dressing, grooming, cooking, and cleaning.

Decibel (dB): A unit of loudness used in assessing hearing; people with normal hearing can hear sounds that are 15-20 dB or softer.

Dementia Infantilis: An old term for childhood disintegrative disorder.

Development: The process of growth and learning during which a child acquires skills and abilities.

Developmental(ly) Delay(ed): In children birth to eighteen, development that is significantly slower than average.

Developmental Disability: A condition originating before the age of eighteen that may be expected to continue indefinitely and that impairs or delays development.  Such conditions include autism, pervasive developmental disorders, and mental retardation.

Developmental Evaluation: See Assessment.

Developmental Milestone: A goal that functions as a measurement of progress in development overtime; for example, rolling over from back to front or speaking in two-word phrases:

Developmental Test: A test, usually given to preschool children, which assesses developmental skills in multiple areas – for example, gross and fine motor, language, and cognitive abilities.

Diagnosis: The name of the disorder identified after an evaluation.

Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM IV): A manual published by the American Psychiatric Association that defines and describes the diagnostic criteria for mental disorders, and provides systematic descriptions of them.

A publication used to diagnose autism spectrum disorders.  The fourth edition is the most current version of this publication.

Dietitian: A professional with expertise in food and nutrition; registered dietitians have completed an internship and passed a national exam. (This is in contrast to a nutritionist, who does not have to meet any particular qualifications to use that title.)

Direct Therapy: Process of work between therapist and child.

Disability: A term used to describe a delay in physical or cognitive development. The older term, "handicap," is also sometimes used.

Discrete Trial: Part of ABA therapy, a trial is a sequence composed of three parts: a direction, a behavior, and a consequence.

Discrete Trial Teaching (DTT): An instructional technique that is part of Applied Behavior Analysis. This technique involves four steps: 1) presenting a cue or stimulus to the learner; 2) obtaining the learner's response; 3) providing a positive consequence (reinforcer) or correction; and 4) a brief 3-5 second break until the next teaching trial is provided. See Applied Behavior Analysis.  Also called Discrete Trial Training or Discrete Trial Therapy.

Disintegrative Psychosis: Another term for childhood disintegrative disorder.

Dispute Resolution Procedures: The procedures established by law and regulation under IDEA for the fair resolution of disputes regarding a child's special education.

Dopamine: One of the neurotransmitters in the brain; it is presumed to play a major role in regulating movement.

DSM IV: See Diagnostic and Statistical Manual of Mental Disorders (DSM IV).

Due Process Hearing: A hearing at which parents present evidence that the school district is not properly educating their child.

Dysfluencey: An interruption in the flow of speech, for example, stuttering.