They're just three little letters, but the dollar signs attached to them are about to make a profound impression on governments and taxpayers.

ABA, which stands for applied behavioural analysis, has been around since the seventies, but is only now entering the Canadian vernacular.

Parent advocates of autistic children are suing provincial governments and school boards, who in turn are loath to provide the therapy because it can cost between $40,000 and $60,000 per child per year.

UCLA psychologist Ivar Lovaas is considered the granddaddy of ABA, a system of behavioural modification that uses basic principles of psychology -- positive reinforcement, where children "work" for rewards such as candy or toys -- to gradually teach autistic children language skills and how to play appropriately.

Prof. Lovaas's 15-year study, published in 1987, showed 47 per cent of autistic children who received intensive early intervention before age 4 achieved "normal functioning."

He says autistic children need about 40 hours a week of the one-on-one treatment, which should focus first on language and speech deficits, then on integration with peers.

Intensive behavioural intervention, of IBI, is an umbrella term that includes Lovaas therapy, but provincial governments use it to refer to a wide range of intensive early-intervention programs, particularly those that are offered fewer than 40 hours a week.

Because of its claims to "normalize" autistic children, ABA has become the gold standard for parent advocates who are demanding it from health departments and schools.

"Everybody wants their kid to be cured, and they're being told that this is the only way to cure your kid," said Bryna Siegel, a psychologist at the University of California in San Francisco.

"So they'd be crazy not to want this."

There are organizations such as Families for Early Autism Treatment (FEAT) that promote only Lovaas treatment.

Sabrina Freeman, a member of the B.C. chapter of FEAT, was one of the four people who successfully sued the provincial government.

The B.C. Court of Appeal recently ordered the province to provide ABA to four children, one of them Ms. Freeman's daughter.

Prof. Siegel said that although there's no question ABA works, it's not clear whether it works significantly better than other treatments.

In her own research, she found children who do well with ABA are self-learners who started out with fewer symptoms of autism: normal nonverbal IQs, some language, and a sense of curiosity.

Students in school-based intervention programs did very well, too, if their parents put a lot of effort into integrating them into the community.

"Typically these were intact families, at least one of the parents quit whatever they were doing full time to do this full time, and they really had a sense of keeping the child meaningfully engaged every moment of the day," she said.

Some of the other treatments and therapy that have shown results include TEACCH, a developmental program that uses structured teaching, and the Picture Exchange Communication System, or PECS, which employs pictures on cards to teach children to construct simple sentences.