A common procedure in a controlled intervention study where the participants who do not receive the intervention under evaluation receive a standard intervention or one that they have been receiving previous to the evaluation.

This denotes the fact that in conversation a person generally does not interrupt what another is saying, but waits until there is a suitable gap and responds by following on from their point(s). People with autism may have difficulty with turn-taking, appearing impolite because they interrupt the other person, perhaps with a comment that seems irrelevant to the topic. (See also reciprocity.)

A research method used to evaluate how frequently a particular condition or characteristic co-occurs in both members of monozygotic (identical) twin pairs as compared with dizygotic (non-identical) twins. Higher co-occurrence (concordance) in monozygotic twins provides evidence that the condition or characteristic is genetically inherited. Used in exploring the genetic basis for autism.

Term used (e.g. in research) to denote the kind of development which is seen in the majority of the population, as contrasted with the characteristics of people with a condition such as autism. It is often used in describing children as that is when most development is expected to occur, and when certain key milestones (such as walking and the onset of speech) are typically attained in a broadly regular sequence. (See also neurotypical.)

Finding some sights, sounds, tastes, smells or touch distressing or unbearable (see sensory hypersensitivity). Alternatively appearing not to notice some sensory stimuli (see sensory hyposensitivity).

Slight changes in the DNA sequences which makes up genes, as a result of mutations. Such changes may alter the instructions coded by a gene, leading to alterations in physical or psychological traits and behaviour.

A term sometimes used for the cognitive style characterised by focusing on individual details rather than the overall form, meaning or gist. In autism this may be especially apparent in the visual processing of scenes, and in language processing, where word meanings are processed individually rather than in their context within sentences. However, the evidence for this processing style in autism is mixed.