Free ABA Basics/Discrete Trials

Discrete Trials were originally used in experimental studies with animals to demonstrate how learning was influenced by rates of reinforcement. The Lovaas program was developed by Ivaar Lovaas at the University of California and adapted as a therapy for developmentally delayed children and children with Autism. Ivar Lovaas has used discrete training trials to help children learn skills ranging from making eye contact and following simple instructions, to developing advanced language and social skills.

Discrete training trials are based on the principles of Applied Behavior Analysis - children will be more likely to adopt behaviors when rewarded, and are less likely to adopt inappropriate behaviors for which they receive no reward or possibly a negative outcome. Lovaas programs are only run by practitioners who have been trained by the Lovaas Institute. The program is highly intensive with 40 hours or more spent each week with children on the autistic spectrum.

Autistic children usually face difficulties in learning. Discrete trials involves breaking behaviors into the smallest functional units and presenting them in a series. Discrete trials are particularly suited in the context of Autism and Asperger's because:


 * The trials are brief and suit short attention spans
 * Discrete trials build motivation through positive reinforcement
 * A proper program helps a child to generalize learned skills to other areas of life
 * Instructions are concrete, concise and without background 'clutter' ( i.e. a noisy classroom).

Ideally intervention is started early when the child is two to three years old and parents are involved to apply the same techniques consistently with their child. The first stage of the program uses Discrete Training Trials to concentrate on:
 * Self-help and receptive language skills
 * Nonverbal and verbal imitation
 * Appropriate play.

The second stage of the Lovaas program concentrates on expressive language and interactive play with peers. The final stage focuses on:
 * Academic tasks
 * Socialization skills
 * Cause-effect relationships
 * Learning by observation.

Inappropriate behaviors such as violence, screaming, self-stimulatory behaviors are managed by ignoring, time-out, shaping and the delivery of a loud "no" or slap on the thigh. The early Lovaas programs attracted negative publicity for their use of "aversives" such as striking, shouting "No!" at the child, or using electroshocks. These procedures have been widely abandoned for over a decade and the focus is now mainly on positive reinforcement.

Discrete trial training takes a task or process a child needs to learn and breaks it down into small discrete steps which can be taught in a graduated way. Discrete trial training normally occurs on-on-one with the therapist or parent prompting the child to do a specific action and rewarding success with positive reinforcement. This is based on the ABC model:

A - Antecedent - A directive or request for the child to perform an action.

B - Behavior - A behavior, or response from the child - successful performance, noncompliance, or no response.

C - Consequence - A consequence, defined as the reaction from the therapist, which can range from strong positive reinforcement (i.e. a special treat, verbal praise) to a strong negative response, “No!”

Discrete Training Trials are highly structured with the choice of stimuli, the criteria for the target response, and the type of reinforcement which is to be provided all clearly defined before each trial commences. Only the child's correct responses are reinforced whereas incorrect or off-task behaviors are ignored (Schreibman, Kaneko, & Koegel, 1991).

Wetherby and Prizant (2000) noted that the initial focus is on adult control and child compliance. Despite the frequent use of verbal prompts, teaching is usually conducted with minimal contextual supports in an effort to encourage the child to develop comprehension of the adult’s spoken language (Wetherby & Prizant, 2000).

The components of a discrete trial are as follows:
 * Instruction (generally a command or request, but it may also be a visual stimulus)
 * Prompt (assistance given to promote a correct response, it may not occur in all trials)
 * The child's response
 * Feedback or other consequences (most commonly rewards and/or praise)
 * Interval (a few seconds between trials for the child to process information).

Discrete trials can be used to develop most skills, which includes cognitive, verbal communication, play, social and self-help skills. A basic example might be for Suzie to brush her hair. The first step may be simply to pick up the brush.

Therapist: “Suzie, pick up the brush”. The therapist takes Suzie's hand and wraps it around the brush. After a short interval, the therapist says “Suzie, pick up the brush” again. Suzie does not respond so the therapist wraps Suzie's hand around the brush again. On the third time, Suzie makes a tentative move for the brush but the therapist still needs to wrap her hand around the brush. "That's a good try, Suzie." On the fourth time, Suzie grabs the brush. "That's really good, Suzie!" The therapist gives Suzie a muesli bar.

A prompt helps a child to do the desired behavior after the instruction has been given. A common problem is that a child may become overly reliant on these prompts, so it should be phased out quickly once the child is able to do the desired behavior.

Prompts can take various forms. Using the above examples, some prompts could be: Physical prompting (guiding Suzie's hand to the brush)
 * Verbal ("Reach your hand out to the brush, Suzie")
 * Modeling (Grab the brush yourself and hope Suzie will copy this)
 * Gesture (pointing at the brush).