At the start of autism therapy, the therapists use physical rewards such as food and toys until they become paired (i.e. associated) with these rewards. Gradually, the therapists would also use social rewards such as hugs and praise in conjunction with physical rewards.
Over time, the therapists raise the difficulty for earning the rewards and eventually replace the physical rewards with the social ones. As the child learns more and more components, they can be generalized and then combined into useful skills.
ABA is the only therapy for autism endorsed by the U.S. Surgeon General. ABA programs used in early intervention for autistic children often require up to 40 hours per week of one-to-one training over a continuous period of 2 or more years.
Based on groundbreaking research published by psychologist B.F. Skinner and his colleagues, it was successfully used in 1967 to treat autism. It became popular in 1993, after extraordinary gains were documented ("Long Term Outcome for Children With Autism Who Received Early Intensive Behavioral Treatment" by McEachin, Smith, & Lovaas) as well as the publication of Catherine Maurice’s book ("Let Me Hear Your Voice”) about her two children’s recovery from autism.