Discrete Trial Training - DTT
What is Discrete Trial Training and how is it used in ABA Therapy?
Discrete Trial Training, or DTT, is one of the most common types of therapy used to treat autism spectrum disorder. Back in the 1980s, Dr. Ivar Lovaas developed discrete trial training as a technique for working with children with autism. It’s a primary component of the Lovaas Method, one of a number of different techniques applied behavioral analysts use to address behavioral issues associated with ASD.
Discrete trial training relies on the ABCs of applied behavior analysis: Antecedent-Behavior-Consequence. It is not a separate type of therapy from ABA, but rather just one of many types of treatments rooted in applied behavior analysis.
Breaking Behaviors Down… and Putting Them Back Together Again
The key aspect of DTT is that it breaks behaviors down into very small, discrete components, and reinforces them methodically and sequentially to build up into one overall desirable behavior.
Linking a number of separate skills together in this way is called chaining.
Discrete trial training provides a controlled way to isolate and reinforce behaviors that have complex antecedents or consequences, like how to behave at lunchtime in the cafeteria at school. When you break it down, you might be surprised by the number of different small hurdles that need to be cleared during a 40-minute lunch break: Recognizing the lunch bell… going to the cafeteria… lining up quietly and getting a tray… finding a place to sit in the social chaos of the cafeteria… cleaning up after yourself… and making it to the next class on time.
Discrete trial teaching breaks it all down into individual steps, each one described and practiced with clear and direct instruction. In its final phase, DTT then puts all these steps back together to form the complete sequence of events that together comprise the lunch break
There are five steps to each DTT trial:
Consequence for the response (correct or incorrect)
Interval between trials
Discrete trail teaching can also be useful in cases where the behavior is not apparently complex, but where being able to adopt the behaviors immediately would nonetheless be difficult using other methods of ABA. People on the low-functioning end of the autism spectrum, for example, might benefit from DTT for a behavior as simple as asking someone if they want to play. Learning the sounds of each individual word or even conceptualizing play could each require a separate discrete trial.
The therapist provides prompts to the patient designed to elicit the correct behavioral responses. When the therapist gets the response they’re after, a reward is offered to positively reinforce that behavior. This activity is designed to shape the responses, providing guidance so that the prompts are not simply seen as random antecedents but instead as part of an overall structure of behavioral patterns. With this structure in place, many children are able to go on to manage their own behaviors effectively on their own.
There is a considerable amount of research showing that DTT therapy results in positive outcomes. In fact, ABA earned a lot of its scientific stripes by proving itself effective in treating ASD during those DTT studies.
However, most modern practitioners of DTT combine it with other forms of ABA, such as Natural Environment Training, which work to alleviate many of these concerns. As a body of practice, ABA, including DTT, continues to be the most effective treatment available for ASD, as well as many behavioral issues not related to autism.