Applied Behavior Analysis, or ABA, is a method of teaching children with autism and Pervasive Developmental Disorder. It is based on the premise that appropriate behavior including speech, academics and life skills can be taught using scientific principles. ABA assumes that children are more likely to repeat behaviors or responses that are rewarded (or "reinforced"), and they are less likely to continue behaviors that are not rewarded. Eventually, the reinforcement is reduced so that the child can learn without constant rewards.

Research shows that ABA works for kids with autism. "Thirty years of research demonstrated the efficacy of applied behavioral methods in reducing inappropriate behavior and in increasing communication, learning, and appropriate social behavior," according to a U.S. Surgeon General's Report.

The most well-known form of ABA is discrete trial instruction (DTI). Skills are broken down into the smallest tasks and taught individually. Discrete, or separate, trials may be used to teach eye contact, imitation, fine motor skills, self-help, academics, language and conversation. Students start with learning small skills, and gradually learn more complicated skills as each smaller one is mastered.

If a therapist is trying to teach imitation skills, for example, she may give a command, such as "Do this," while tapping the table. The child is then expected to tap the table. If the child succeeds, he receives positive reinforcement, such as a raisin, a toy or praise. If the child fails, then the therapist may say, "No." The therapist then pauses before repeating the same command,ensuring that each trial is separate or discrete. The therapist also will use a - such as helping the child tap the table - if the child responds incorrectly twice in a row.

Many programs use prompts for every trial, so the child is always correct and always reinforced by praise or a toy. This technique is called "errorless learning." The child will not be told "no" for mistakes but rather will be guided to the correct response every time. The prompts will be reduced, so the child will learn the correct response without them.

ABA may take place in the home or in special preschools. A consultant, usually someone with a master's or doctoral degree in psychology, often supervises the therapy.

Some people incorrectly assume that ABA is synonymous with the method developed by Dr. O. Ivar Lovaas, a pioneering researcher in the Psychology Department at UCLA. Lovaas describes one form of ABA. In 1987, he published a study showing that almost half of the 19 preschoolers involved in intensive behavioral intervention -- 40 hours per week of one-on-one therapy -- achieved "normal functioning. Note: Several decades ago, Lovaas described using mild physical punishment for severe behaviors during therapy sessions. He no longer advocates such punishment, and current behavior therapists do not use it.

ABA programs usually draw upon Lovaas's decades of research, but they also may incorporate different methods and tools.

Applied Verbal Behavior or VB is the latest style of ABA. It uses B.F. Skinner's 1957 analysis of Verbal Behavior to teach and reinforce speech. Skinner describes categories of speech, or verbal behavior. Mands are requests, echoes are verbal imitations, tacts are labels, and intraverbals are conversational responses. A VB program will focus on getting a child to realize that language will get him what he wants, when he wants it. Requesting is often one of the first verbal skills taught. Some parents say VB is a more natural form of ABA. Like many Lovaas ABA programs, a VB program will use errorless teaching methods, prompts that are later reduced, and discrete trial training. Behavior analyst Vincent Carbone has helped popularize this approach.

One drawback to ABA/VB: some school districts and insurance companies do not pay for ABA, and it can be expensive for parents to fund. If you decide to pay for it yourself, carefully research the credentials of anyone claiming to be an ABA or VB consultant or experienced therapist. A consultant should have, at a minimum, a master's degree in psychology or ABA, or should be closely supervised by someone who does. When hiring therapists, some families find volunteers or students willing to work for lower pay in order to gain experience with autism.