Discrete Trial Teaching (DTT)
Discrete Trial Teaching (DTT) is an intervention method based on the science of Applied Behavior Analysis (ABA). It is a highly structured method of teaching skills by breaking them down into smaller, teachable components. This intervention method is based on the work of Dr. Ivar Lovaas which began in the 1980’s. The use of DTT when teaching skills can maximize learning of skills including cognitive, communication, play, social and self-help skills. There are 5 main techniques involved in DTT:
1. Breaking skills down into component parts
2. Teaching each skill component until mastery is attained
3. Intensive teaching sessions
4. Using prompts as needed and fading prompts as appropriate
5. Using reinforcement strategies to increase skills
The key to teaching using this method is breaking down skills into component parts, teaching each component intensively and systematically (using prompts when and where necessary) and consistently using reinforcement procedures to increase the likelihood of the student learning the skill. All of this is ultimately accomplished by applying the 3-term contingency to the skill being taught.
The three-term contingency: Sd - R - Sr+
The Discriminative Stimulus (Sd)
The Sd is the stimulus within the environment that signals a response is required (and that reinforcement is available). The Sd can be an instruction or some other environmental cue. The Sd should be clear and concise especially during the initial stages of learning. For instance, an instruction for receptively identifying colors might be “touch yellow” rather than a more wordy instruction like “Anna, will you please point to the yellow square on the table?” As the student learns the skill, more complex instructions can be introduced, but simplifying the instruction initially helps avoid confusion about what the expectation is. The student should be allowed a maximum of 5 seconds to respond in most cases.
The Response (R)
The response is the specific skill or skill component you’re teaching. The expected and acceptable response should be clearly defined so there is consistency across people implementing the intervention. As an example, if the response for “touch yellow” is not clearly defined, one teacher might be accepting when the student lightly touches the card and another might be accepting when the student slaps the card and yells “yellow!” If the expectations aren’t clear and consistent, learning will happen less rapidly and the student might be learning the incorrect behavior.
It is unlikely the student will know how to respond to the Sd when teaching begins, therefore prompting needs to be used to teach the skill. Prompting strategies should be selected based on the student and the specific skill being taught. Possible prompting strategies include verbal, physical. visual, demonstration or proximity prompts. It is important to plan what prompting strategies will be used and also how the prompts will be faded. Prompts should be faded as quickly as possible to avoid dependency on prompts.
The Reinforcing Stimulus (Sr+)
All correct responses should be immediately reinforced. This means the students should be given something following correct responses (even when prompted) to signal that the correct response was given. By reinforcing correct responses, we are increasing the likelihood correct responses will be given again. If the correct response was not given, no reinforcement is delivered. This clearly shows the student the response given was not correct because it did not result in a positive outcome. By not reinforcing we are effectively decreasing the likelihood of the student giving the incorrect response.Reinforcement is only effective if it is something the student values. It can take many forms such as praise, high-five, tickles, toys, food/drink, a break, a sticker or a token to name a few. The key here though is that it has to be something the student actually wants. Many times reinforcers change due to satiation (the student has had their “fill” of the item or activity) therefore it is important to vary reinforcers and constantly be assessing the value of reinforcers in the moment.