Jessica Park, The Potala Palace in Tibet (detail), 1990, collection of Andrew Failes

The words we use to describe autism and the individuals affected by autism matter. They have also changed a great deal over time. Shifts in language have often indicated changes in thinking about autism and intervening in the lives of people with autism. Words have always been central to the description, perception, and experience of autism.

This glossary clarifies some common terminological transformations in autism history and defines vocabulary that is either antiquated, specialized, or both.

Applied Behavior Analysis (ABA)

Applied Behavior Analysis describes an intensive, one-on-one method of working with children, for many hours each day, for months or even years at a time. ABA originated in the work of behaviorists during the 1960s, including UCLA psychologist Ivar Lovaas. They argued that understanding what caused severe problems with communication and interaction was unnecessary. Instead, their goal was to demonstrate that language and behavior could be significantly improved through techniques of behavioral reinforcement. ABA was championed by many parents and teachers. It eventually evolved into a professional specialty in its own right.

Asperger Syndrome

Asperger’s was first listed in the DSM-IV in 1996 as one of four possible subcategories under Autistic Disorder. It was a diagnosis intended for children who met the criteria for autism but who displayed no significant delay or impairment in the areas of language and cognitive development. In practice, Asperger’s was used for children whose autism included unique or unusual preoccupations and talents in technical, scientific, or musical fields. The syndrome was named after Austrian physician Hans Asperger, who first described “autistic psychopathy” in 1944. Asperger Syndrome was popularly understood as “high-functioning” autism.

Autism Spectrum

This term refers to the fact that autism spans a wide range of cognitive and other abilities, from severe mental retardation to extremely high intelligence, from complete lack of language to exceptional facility with language. The spectrum concept, popularized in the 1980s, turned autism into something more varied than the classical syndrome described in the 1940s, and Autistic Disorder became an umbrella diagnosis in the DSM-IV in 1996. Lorna Wing, a British psychiatrist, epidemiologist, and parent of an autistic daughter, is often identified as the original advocate of the spectrum concept.

Childhood Psychosis or Schizophrenia

These terms were used from the early part of the twentieth century into the 1970s. They described autism, among other conditions, and indicated the probability that psychosis or schizophrenia in childhood would lead to psychosis or schizophrenia in adulthood. The two terms were often used interchangeably, classifying autistic-like behaviors as symptoms of severe mental illness.

Classic Autism (aka Infantile Autism or Kanner’s Autism)

This term was used to designate the syndrome described by Leo Kanner in his 1943 case study of eleven children. Kanner emphasized the children’s fascination with objects and indifference to people, feeding difficulties in infancy, rhythmic bodily movements (such as spinning and jumping) and their preference for rigid routine and repetition over any kind of novelty.


Feebleminded was a common term before World War II, a synonym for mental defect, deficiency, or retardation long before developmental disability entered the American vocabulary. During the classic era of eugenics, in the early twentieth century, feeblemindedness also suggested the heritability of low intelligence and the importance of enacting policies that would prevent its reproduction from one generation to the next.

Prevalence v. Incidence

Prevalence refers to the total number of cases of autism in a population or population subgroup. Incidence refers to the number of new autism cases documented during a specific period of time, such as one year. Both prevalence and incidence are typically expressed mathematically as rates or percentages. Prevalence rates indicate how widespread autism is. In contrast, incidence rates indicate the risk of developing autism. Virtually all epidemiological studies of autism have measured prevalence. Incidence has been trickier to study because the age of onset has been difficult to determine, diagnostic criteria have changed significantly over time, and diagnostic practices have varied widely.


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