A.B.A. Applied Behavior Analysis. Not ABBA, the Swedish disco band from the 1970's. ABA is the scientific study of human behavior.
Ever heard of Pavlov's salivating dogs? That's where we started, in the 1890's, in a Russian physiologist's laboratory. Pavlov wasn't studying behavior or even psychology; he was studying the digestive system, and he unwittingly stumbled upon classical conditioning (or, respondent conditioning). Pavlov noted that his canine test subjects began to salivate at the mere sight of the lab assistants (when food was not present). He realized that through repeated exposures, the lab assistants (and their trademark, white lab coats) had become paired with the food, and that the coats now produced the salivation that the food used to produce. The lab coats had become conditioned stimuli. Very interesting!
John Watson (1878-1958) later claimed he could take any child and turn him into a doctor or a lawyer or, pretty much, anything he desired, after showing he could condition a baby into fearing a white rabbit. Poor Little Albert.
B.F. Skinner's work in the animal research laboratory revolutionized the field of behavior analysis. Skinner gave us a brand of behaviorism that I, personally, prescribe to: radical behaviorism, a school of thought that attempts to understand all behavior through science, even private events, like thoughts and feelings; the experimental analysis of behavior, a natural science approach to the study of behavior, which gives us a scientific basis to make educated treatment decisions; the Skinner Box (pictured below), verbal behavior; schedules of reinforcement; and much more.
Applied behavior analysis is used outside the laboratory. This is what behavior analysts do every day, in the clinics, in the home, in the community. Some of what we do includes behavioral assessment; teaching new skills, like academics, social skills, communication, toileting, hygiene, appropriate play skills, etc.; decreasing inappropriate behaviors, like self-injurious behaviors, tantrums, aggression, self-stimulatory behaviors, etc.
ABA today is most often used to treat Autism Spectrum Disorders, as it's the only evidence-based treatment for ASD. That means that ABA has research behind it showing that it is effective in treatment ASD. However, ABA can be applied to any behavior, regardless of a diagnosis. That goes for children with disabilities, typically developing children, pets, and husbands. Something to keep in mind, ladies.