Discrete Trial Teaching

Discrete Trial Teaching (DTT) was developed by Ivar Lovaas and is an
evidence-based practice (EBP) that has been used as a method of teaching
individuals with Autism Spectrum Disorder for more than 40 years. It is the
most widely used and well researched form of Applied Behavior Analysis
(ABA).

For children with autism, learning does not always come easily, nor
naturally from observing the people and environment around them. DTT works
well for children with autism, and all children really, because it takes
a complex skill and breaks it down into small simplified steps. Each step
is taught until it is mastered in a structured way.

 The Discrete Trial Cycle:
It has a distinct beginning, middle and ending. The
three main components are as follows:
 

1) Instruction/ Sd (Discriminative Stimulus)
 
2) Student Response
 
3) Feedback/ SR+ (Reinforcing Stimulus)

Inter-Trial Interval (ITI) – this is the transition or pause of roughly 1-3 seconds before the start of the next Discrete Trial Cycle.

The first component of DTT, the Sd, is the instruction that
a RBT therapist gives to their student. This can be in the form of words or
actions given that stimulate a behavior to happen. This must be said or
shown clearly, concisely and slightly louder than a normal tone of voice.
It should not involve the student’s name and be too lengthy, especially
with a new student just starting ABA therapy.

The second component, the Response (R), is the behavior of the child that
happens in response to the Sd or instruction given.

The last component is the Feedback/ SR+ given to the child. This is the
consequence that immediately follows the student’s response. If a correct
response is given, the child is given SR+ right away in the form of a food,
praise, a preferred toy or activity, etc. If an incorrect response or no
response is given, the child receives corrective feedback by being
presented with the Sd again and being prompted (P) with the correct answer
immediately prior to the child’s next response.

It is important to deliver a consequence (Feedback/ SR+) after every response so your student becomes aware of which behaviors or responses are correct and incorrect. Giving reinforcement to correct responses will make it likely
the response will occur again. It’s important to vary your reinforcement.
Highest SR+ for correct responses that include eye contact, focus on the
task and good effort will show the student that this is a behavior to
repeat and therefore learn, because great things happen when I display it.
While, correct responses with poor eye contact, focus and
effort still receives SR+, but at moderate to lower levels.

Here are examples of a Discrete Trial Cycle when a student gives a correct
response and incorrect response.

DTT with CORRECT Response
Materials: 2D images of a ball and bicycle
Sd: “Touch the one you ride on.”
R: Child touches the bicycle picture card.
SR+: “Right on, way to go!” RBT therapist gives lots of tickles.

DTT with INCORRECT or NO Response
Materials: 2D images of a ball and bicycle
Sd: “Touch the one you ride on.”
R: Child looks away, no picture card is touched.
(RBT therapist immediately repeats the Sd and prompts the correct answer)
Sd: “Touch the one you ride on.”
P: Therapist physically prompts the child’s hand to touch the bicycle card, making sure he is looking at the card.
SR+: “That’s right, you ride a bicycle!”
(Follow up with an independent trial)
Sd: “Touch the one you ride on.”
R: Child touches the bicycle picture card
SR+: Fabulous! You got it. RBT therapist gives some tickles.

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