A major breakthrough (in some respects) in the remediation of autistic behaviors came through work spearheaded by Ole Ivar Lovaas, who believed that success could be obtained by behavioral approaches.
Lovaas' approaches—often referred to as Discrete Trial, Intensive Behavior Intervention, and Applied Behavior Analysis—are some of the best known and most widely used in the field and focus on the development of attention, imitation, receptive or expressive language, and pre-academic and self-help skills. Using a one-to-one therapist-child ratio and the "antecedent-behavior-consequence" (ABC) model, interventions based on this work involve trials or tasks. Each consists of (a) an antecedent, which is a directive or request for the child to perform an action; (b) a behavior, or response from the child, which may be categorized as successful performance, noncompliance, or no response; and (c) a consequence, defined as the reaction from the therapist, which ranges from strong positive reinforcement to a strong negative response, "No!"(Autism Society of America, 2001)"
Lovaas' Applied Behavioral Analysis (ABA) methods were the first scientifically validated therapy for autism. Early intervention, generally before school-age, seems to be critical to achieving optimal outcomes.
ABA techniques based on B. F. Skinner's Verbal Behavior have succeeded in helping nonverbal children start to talk, typically going from zero words to several dozen. By allowing children to express their needs, even rudimentary speech can alleviate frustration and tantrums.
The scientific validity of Lovaas's methods is questioned by many professionals as well as parents and autistic's themselves. Lovaas's initial studies looked promising but have not been reproduced by others with the same rate of success. There have not been any double-blind studies that validate ABA, so it is unclear if any improvements seen in children are simply due to their normal course of development.
Many also feel that there are serious ethical problems, and point out that early ABA was based around the use of aversives which are confusing and painful.
ABA may not be appropriate for every autistic or developmentally delayed child. ABA has come into widespread use only in the last decade and the demand is outstripping the supply of committed and experienced service providers. As a result, parents of children need to be extra vigilant in choosing appropriate treatments for their children and especially in choosing providers, who may be inexperienced, use questionable methods or even deceive parents that they are competent to run an ABA or any other program. Such problems have led to horror stories from some parents.