Boy colors in ABA session while therapist watchesApplied behavior analysis (ABA) can be described as a scientific approach to modifying behavior based on an application of learning principles.

Since its emergence, ABA has been utilized in various settings, such as schools, private homes, hospitals, and workplaces. It can be used in therapy to address a range of mental health conditions, including learning difficulties, brain injuries and most notably, autism.

Development of Applied Behavior Analysis

In the early 20th century, John B. Watson proposed his belief that psychology should be concerned with the study of observable behavior as opposed to private internal events. Watson advocated a stimulus-response approach to behavior, in which one's behavior was thought to be determined by environmental stimuli. This school of thought became known as behaviorismLater, through extensive research with animals, B.F. Skinner found that Watson's cause-and-effect approach was too simplistic to explain all forms of behavior, arguing the consequences of behavior were just as influential or even more influential than what had led to the behavior.

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Skinner's experimental work on behavior is often considered the beginning of what is now known as experimental behavior analysis. His ideas were eventually expanded into a comprehensive theory now known as operant conditioning. The theory suggests behavior can be changed through the use of reinforcement and punishment.

Basic principles of operant conditioning have been applied to humans in real-life situations in order to modify behavior and solve problems of social importance. This application of learning principles, in combination with an experimental approach, has come to be known as applied behavior analysis.

Principles and Dimensions of Applied Behavior Analysis

ABA is considered to be scientific because it involves a systematic process of the objective collection of data on the behaviors to be changed. The implementation program is continuously monitored to evaluate its effectiveness. The goal of the process is to change or alter behavior in some way, usually by increasing or decreasing its occurrence. The behaviors targeted are observable, measurable, and usually of social relevance to the individual. ABA is founded on empirically validated learning principles, such as operant and classical conditioning.

The emergence of ABA as a distinct scientific field occurred in the late 1950s and 1960s. In 1968, Donald Baer, Montrose Wolf, and Todd Risley introduced seven dimensions of ABA in the inaugural issue of the Journal of Applied Behavior Analysis. 

These dimensions helped give direction to the field and continue to guide practitioners today.

  • Applied: The behaviors selected for modification are socially relevant to the individual and the individual's family.
  • Behavioral: Behavior analysts are interested in the precise measurement, quantification, prediction, and control of behavior.
  • Analytic: Behavior analysts employ an experimental approach to behavior change in order to demonstrate that any observed change in behavior is a result of the intervention and not other factors. Single-case experimental designs are typically used in ABA.
  • Technological: When implementing behavioral interventions, behavior analysts provide detailed operational definitions and record the procedures used so another qualified behavior analyst can replicate the intervention.
  • Conceptually systematic: The interventions used in ABA are based on empirically validated principles of behavior.
  • Effective: Interventions are considered effective if they produce a change in behavior that is considered to have practical value or social significance, as opposed to statistical significance.
  • Generalizable: Behavioral interventions are only effective if the results extend to a variety of settings, caregivers, or related behaviors and if they are maintained over time.

The Applied Behavior Analysis Process

Applied behavior analysis is a systematic process. Once the behavior to be modified is identified, it is measured and analyzed. This helps the therapist to determine the frequency of the behavior and any situational factors that may contribute to the behavior. Intervention strategies developed to modify the behavior are then implemented in a careful and controlled manner. The controlled application of strategies allows for replication if the intervention is found to be successful. Evaluations are done throughout the course of the intervention to determine its effectiveness, and strategies are modified as needed.

ABA therapists typically use a combination of behaviorist approaches. These include:

  • Discrete trial training (DTT): In DTT, specific skills are broken down into smaller steps, and each step is taught separately. If the correct response is provided, the child is rewarded; if an incorrect response is given, an instructional prompt may be used to guide the child toward the correct response. DTT typically occurs in structured therapeutic settings.
    • A session of DTT might involve a therapist placing a red card and a blue card on a table and asking the child to touch the one that is red. If the child does so correctly, the child is rewarded; if not, the trial is repeated until the correct response is provided several times in a row. If a child has difficulty performing the task, the therapist might provide a prompt. For example, the therapist may point or look in the direction of the red card. Prompts are usually faded out gradually as the frequency of correct responses increases.
  • Incidental training: This method employs the same approach as DTT, but it works to teach behaviors within the context of the child’s daily life. A child could therefore be taught a new behavior while sitting in a classroom and interacting with peers (as opposed to sitting in an office and interacting with a therapist).
    • During a break, a girl might say to her teacher, "Want ball." The teacher could use this as an opportunity for incidental training by asking, "Do you want the red ball or the blue ball?" If the girl elaborates on her initial request by naming the color of the ball she wants, the teacher would reward her with that ball. This aspect of ABA may also be conducted by parents at home. For example, a mother coloring with her son might ask him to pass her the blue crayon. If he does, he would be rewarded, and if he does not, the mother might provide assistance in the form of a prompt.  
  • Pivotal response training: This approach teaches children skills that affect a wide variety of behaviors. When a child masters a pivotal skill, parents typically notice improvement in several other areas.
    • A child who learns to sit quietly, for example, may exhibit better behavior in school, get along with teachers more easily, and listen more attentively to directions. Pivotal response training therefore helps to generalize behaviors that have been learned or improved on in a therapy setting by applying them to everyday situations.

Applied Behavior Analysis and Autism

ABA is considered to be one of best approaches to the treatment of autism. Documented data supports the efficacy of this approach, and ABA has been used successfully to treat autism since the 1960s, when programs were first developed for a classroom setting. ABA continues to help in the reduction of aggressive and self-injurious behaviors displayed by some children with autism, and it also has been shown to further the improvement of social and daily living skills.

Most children learn social and other developmental skills from observing and interacting with their caregivers and peers. Children with autism, however, may have a difficult time developing empathy and theory of mind and therefore are less likely to acquire certain skills from watching others. ABA helps by actively teaching children with autism certain basic skills even they may not understand the underlying concepts. The predictable and repetitive nature of ABA also fits well with the characteristics of children with autism, because they often have a need for structure and routine.

The efficacy of ABA in the treatment of autism has been repeatedly demonstrated by researchers. Ole Ivar Lovaas conducted a landmark study in 1987 in which he compared an experimental group of 19 children who received ABA intervention to a control group of 40 children. Nine out of the 19 children attained average cognitive functioning and were able to function effectively in a regular education setting, while only one of the children in the control group was also able to do so. Other researchers conducted a follow-up study in 1993 to assess the long-term progress of the same students involved in Lovaas' study and found the IQ gains of the experimental group had been maintained.

Similar studies conducted in more recent years have also demonstrated the efficacy of ABA in enhancing the intellectual and academic functioning of those with autism. In 2006, for example, a group of researchers replicated Lovaas' study, comparing 21 children who received ABA intervention to a control group of students in public school special education classes. By the third year of the study, 17 out of the 21 children in the ABA group had been integrated into regular education classrooms, compared to only one from the comparison group.

The extent to which behavior analysts work with individuals who are autistic gives further evidence of the usefulness of ABA in the treatment of autism. According to one recent report by the Association of Professional Behavior Analysts, more than 80% of the applied behavior analysts surveyed reported working with children with autism or other conditions on the autistic spectrum. The use of ABA in the treatment of autism is also supported by many federal government agencies and research institutes, such as the National Academy of Sciences, American Academy of Pediatrics, and the New York State Department of Health. It is also recommended by autism advocacy groups such as Parents for the Early Intervention of Autism in Children (PEACH).

Training and Certification

The Behavior Analyst Certification Board (BACB) is the professional body responsible for certifying behavior analysts. In order to be eligible for the certification examination, individuals must have earned at least a master's degree in behavior analysis or a related field approved by the BACB, such as education, psychology, or social work. They are required to complete specific graduate-level coursework in behavior analysis, as well as several hours of supervised experience. The coursework and experience requirements are described in detail on the BACB website. Once individuals pass the certification examination, they are recognized as Board-Certified Behavior Analysts (BCBA). Recertification occurs every three years and requires the completion of several hours of continuing education.


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