ABA is the applied use of behavioral principles to everyday situations with the goal of either increasing or decreasing targeted behaviors. How this translates into practical application will depend on the specific situation. Nevertheless, all ABA programs share similar components: discrete trial teaching, programming for generalization to the natural environment, reinforcement, prompting and fading strategies, and outcome-based decision-making.
DISCRETE TRIAL TEACHING - this technical term means, quite simply, breaking a task down into smaller, more teachable components, and teaching each component separately.
A cue is given —› the child responds —› a reward is given for a correct response
(Sd) —› (R) —› (Sr)
The cue, referred to as a discriminative stimulus (Sd), is a specific environmental event or condition in response to which a child is expected to exhibit a particular behavior. What this looks like in everyday life is this:
Child 1: Hi! —› (Sd)
Student: Hi. —› (R)
Child 1: [smiles] C'mon! Let's go! —› (Sr)
This type situation occurs every day, multiple times a day, for typically developing children. For children with autism, frequently several skills may be lacking so that the child cannot or is not motivated to engage with the other child. Discrete trial training can address underlying skill deficits in order to increase a student's ability and motivation to respond socially to other people. In fact, the hallmark of discrete trial training is that almost any skill can be broken down into discrete parts so that weak areas can be targeted and strengthened.
Prompts may be given after an Sd to increase the likelihood that the child will demonstrate a correct response that can then be reinforced. Main types of prompts include verbal, physical, positional, gestural and model prompting.
Teaching for generalization - initially, therapy is usually conducted in a less chaotic environment, with the idea that having fewer distractions around in the learning environment will assist the child to focus and learn the task at hand. Programming for generalization takes into account the need for behaviors to occur across all environments, independently, and spontaneously. Thus, criteria are set to include various setting and stimuli and a skill is not determined to be mastered unless and until the child demonstrates independent ability to perform the skill across such environments.
Reinforcement - when we think of reinforcement, we naturally think of things that we like. Behaviorally speaking, reinforcement means only that a behavior, when followed by reinforcing stimuli, is more likely to increase over time. Thus, in an ABA program, each child's reinforcement (items and timing and activities) is likely to vary widely. All ABA programs should include a reinforcer assessment; and these assessments should be reviewed regularly over time to capture changes in the child's preferences. Reinforcers should be built on items and activities that are motivating to a child.
When behaviorists talk about reinforcement with families and other lay persons, it is often in the context of presenting desired items or activities to a student. This is termed "positive' reinforcement. Another form of reinforcement is "negative' reinforcement - that is, the removal of an undesired (aversive) stimulus - which, when removed consistently over time, the target behavior is likely to increase. This concept is more easily understood in context. For example:
|Child: Mommy, I want ice cream.|
|Mom: No, sweetie.||Sd for child|
|Child: [tantrumming] I want it now!!!!! [screaming]/td>||Sd for Mom||R for child|
|Mom: Okay, but just this time. And for heaven's sake, be quiet. [gives ice cream]||R for Mom||Sr+ for child|
|Child: [quiet] [takes ice cream]||Sr- for Mom|
Who was positively reinforced? Who was negatively reinforced?
In behavioral terms, the flip side of reinforcement is punishment, such that rather than increasing behaviors, punishment is measured in decrease of behaviors. Just to repeat, punishment, in behavioral terms, means only a decrease in a targeted behavior. Punishment does not always mean the application of aversives, restraints, spankings, or time outs. It means the decrease of targeted behaviors following the presentation or removal of aversive consequences. There are a few main types of techniques used in punishment procedures: time out from preferred objects and activities , response cost (removal of a token (in token economy) when targeted behavior occurs), and overcorrection (e.g., washing the entire table when only a portion was dirty).
In addition, there are other strategies that are not punishment that also serve to decrease unwanted behaviors. These strategies include differential reinforcement and extinction. Therapists, teachers and parents all learn how to differentially reinforce alternative and other behavior, other rates of behaviors, and incompatible behaviors which either decreases behavior by using reinforcement or results in an increase in positive behaviors which allows for little time for unwanted behaviors to occur. Extinction is the process of withholding a consequence that has previously been provided following behavior. For example, in the previous scenario, the child has learned to have a tantrum in order to get ice cream. Under extinction, the mom would not give in and would not provide ice cream after the tantrum. Extinction should never be used in isolation and it should be paired with other programs that include reinforcement.
Prompting Strategies - There are several prompting strategies, but the approach you will hear about most often is the use of prompting hierarchies: most-to-least and least-to-most. A most-to-least strategy is typically used when a student is first learning a skill; the first trial is prompted with the most intrusive prompt appropriate to accomplish the skill successfully. The first trial is followed by second using a lesser intrusive prompt; this second, less-prompted successful trial is reinforced. A least-to-most- trial is typically used when a student has shown in the past an ability to accomplish successfully a task (e.g., usually 80% or more of trials). No matter which strategy is used, it is critical to remember to fade prompts as quickly as is possible. Finally, remember to differentially reinforce those responses that require less prompting.
Data-based decision making - What truly sets ABA therapy apart from other interventions is its reliance on objective information to make programming decisions. Any chosen ABA intervention is constantly evaluated for its effectiveness by an analysis of the data collected. Therefore, it is critical that all members of an ABA team be aware of the criteria for correct responding, that all therapists are consistent in the collection of data, and that all team members be taught to think critically about the strategies used, understanding that lack of progress is not the child's fault, but the lack of having found or applied the appropriate teaching strategy.
Research supports intensive intervention, anywhere from 25 to 40 hours per week for 12 months a year for at least 2 years, depending on the individual's needs and responsiveness to interventions. This is a lot to fit in, and children do get tired. Thus, it is important to make decisions about the intensity, timing and frequency of therapy based on the child's capacity. Ideally, therapy is equally spaced throughout the week (e.g., at least one session per day), and the day. Sessions are typically provided in 2-3 hours blocks, with 10-15 minute breaks every hour. Highly structured lessons typically are delivered for about half the time allotted, with the other half the time dedicated to teaching in the natural environment - systematically reinforcing and generalizing skills taught in the structured setting.
Play and social skills are more effectively taught in the natural environment. However, in order to obtain the necessary intensity of training, the family and therapists will have to contrive situations so that the targeted skill occurs with relative frequency.
(1) National Research Council (2001), Educating Children with Autism. Committee on Educational Interventions for Children with Austism. Catherine Lord and James P. McGee, eds. Division of Behavioral and Social Sciences and Education. Washington, D.C. National Academy Press