In-depth observation and description of the specific characteristics of a selected individual. Pooling of case study material across individuals may permit identification of general features. The method is used by clinical practitioners, and in some forms of research.

An approach which some have misleadingly claimed alleviates or cures autism by eliminating ‘excess toxins’ from the body. Described by the UK’s National Institution for Clinical Excellence (NICE) as harmful and to be avoided.

A term describing interventions which involve following the child's own interests and motivation as a means of encouraging interaction and learning. (See also adult-directed approaches.)

Structural units in all living cells, composed of long strands of DNA along which genes are located. (See also deoxyribonucleic acid (DNA) and genes.)

The psychological processes involved in thinking, learning, planning and problem-solving, and in the understanding and use of language.

Characteristic strategies or preferences for thinking and processing information.

A medical term for the presence of one or more conditions or disorders alongside a primary condition. In autism, epilepsy is a common co-morbid condition.

The extent to which the same (or a similar) condition, characteristic or trait is present in both members of a pair of twins or siblings.

A sequence of items or entities running along a continuous scale such that differences between items are gradual rather than abrupt.

A group of participants in an experiment or other systematic study used as a standard against which others are measured. This could be a group who do not receive an intervention, or it could be a group who do not have autism.