There are MANY different ways to apply the science of ABA, such as Natural Environment Teaching, Verbal Behavior, and DTT: Discrete Trial Teaching. Many people think DTT is all ABA is; that all ABA therapists do is sit at a table with flashcards and small pieces of candy. That is a common misconception, but ABA is broad and multifaceted. Applied Behavior Analysis is a science that can be applied in a variety of ways to teach new behaviors, and DTT is just one branch on the ABA tree.
The 1987 Lovaas study (which is THE research study in the field of ABA) utilized Discrete Trial Teaching in order to teach many complex skills to a group of children with Autism. Before this study was published, it was considered a widely accepted fact that children with Autism could not learn. Parents of children with Autism were told to institutionalize their child and try to move on with their lives. It cant be emphasized enough what the Loovas study did to demonstrate that kids with Autism CAN learn when the teaching is modified.
DTT is widely used today and probably the best known type of ABA. If your child receives ABA services at a clinic/Autism school, or from an agency, they are probably using DTT techniques for the sessions. It is common that lower functioning or younger children start with a more structured and rote DTT style, and eventually over time or as the child develops they transition to a more naturalistic learning style, such as NET or Incidental Teaching.
When people make complaints or negative statements against ABA, they usually critique ABA for being too robotic, focusing on repetitive drills, giving kids bites of candy all day, etc. Although distorted and inaccurate, there is some truth to these complaints. The DTT method does focus on breaking down skills, repetition, and reinforcement. However when done properly by qualified staff, DTT can bring about amazing and significant gains in language, imitation, attending, self-help, motor, and play skills in children with Autism. The research is extensive and conclusive: DTT works.
Let’s take a closer look at the DTT method--
- Teaching Trial: For the DTT method, the following teaching trial is used: Present materials, give SD, prompt incorrect response or reinforce correct response, clear materials. That entire process is called a teaching trial, and it is repeated over and over in a therapy session. It should move at a brisk pace, and the therapist should be collecting trial by trial data after each trial has ended. Each trial is a learning opportunity, and the goal of a DTT session is to give the child hundreds of learning opportunities in order to teach specific skills. Younger children usually do 10 trials of each skill, while older children might do 5 trials of each skill.
- Breaking down tasks- DTT breaks down complex skills into small, separate tasks to teach. So what is considered a complex skill? Well, pretty much everything. For a child with Autism, learning to write their name could be a 5-10 step process. For example, if the child’s name is “Adam”, first they learn to individually trace “A”, then “d”, and so on. After tracing, they learn to write each letter individually. Finally, the child is given paper and pencil and told “Write your name”, as the therapist provides letter prompting (therapist says as child writes “A…d…a…m”). Over time the therapist would remove her assistance until the child can independently write his name. Sound complicated? It’s really not. The goal when using a DTT approach is to break down the skill as much as is necessary for the child. It might not take that many steps for your client to learn to write his name. Or, your client may need even more steps. Let the child’s progress determine how far to break down the skill. If you have been stuck on a particular skill for weeks, it probably needs to be broken down further to help the child understand.
- Mass Trial vs. Mixed Trials- Depending on the ability and functioning level of the child, you would teach using “mass” or “mixed” trials. A mass trial simply means you are asking the target multiple times in a repetitive manner. That would look like this: “Trial 1: Touch dog…Trial 2: Touch dog…..Trial 3: Touch dog”. Mass trialing is typically used to teach very young children, children new to ABA, or lower functioning children. Some programs add in generalization at this step by changing the stimuli for each trial. So the 1st trial the child touches a photo of a brown dog, the 2nd trial the child touches a photo of a white dog, and so on. Mixed trialing, also called random rotation, is when you teach targets in a random order and do not use repetition. That would look like this: “Trial 1: Touch dog…Trial 2: Give me red…Trial 3: How old are you?”. Typically you want to transition from mass trialing to mixed trials; although with some children they may need the repetition of a mass trial in order to learn.
- SD---> Response- The SD is simply the instruction or demand you present to the child. Examples of SD’s include: “Touch your nose/Stand up/What number? /Touch apples”. With DTT, the SD leads to a specific desired response. If I say to a child “Touch your nose” there is a specific response I want the child to do. If the child does the response correctly, I provide reinforcement. If the child doesn’t respond correctly, I provide prompting. The SD must be consistent across time, therapists, and settings. If the morning therapist says “Touch your nose” and the afternoon therapist is saying “Show me your nose” that could be confusing to the child, and could slow down learning. The SD tells the child what you want them to do, and their correct response is how they contact reinforcement. It is the reinforcement that increases the likelihood that the child will respond correctly in the future.
- Reinforcement- Reinforcement is a critical part of any ABA program, but particularly so with DTT. This is because DTT has so many learning opportunities in a session. Depending on the schedule of reinforcement being given, the child may be reinforced hundreds of time in a therapy session. With a continuous or dense reinforcement schedule, every correct answer contacts reinforcement. With an intermittent or thin reinforcement schedule, only some correct answers contact reinforcement. The schedule of reinforcement you use will depend on the child. Reinforcement must be easily accessible and ready (a bag of unopened chips is a poor choice. The chips should be opened and placed into a bowl or on a plate for easy access), yet out of reach of the child. Reinforcement should be varied, rotated often, and given in small amounts. If the reinforcer is tickles, then don’t tickle the child for 5 minutes after one correct answer. Tickle the child for maybe 4 seconds, and then continue teaching. Many people ask me if DTT sessions have to use food treats. The answer is no, they do not. The reason why so many DTT sessions use food reinforcers is because very young children or children new to ABA often don’t find social interaction, adult attention, or toys/games reinforcing. For those children, the therapists have to use things like candy, chips, or ice cream because that’s all the child likes. However the goal is always to transition the child away from food treats as soon as possible.
- Data Collection- Data collection for a DTT trial is done after each trial. As the child is contacting their reinforcement, the therapist is writing down how the child performed at the task. The type of data sheet used can range from very simple to complex. It can be checkmarks, a plus/minus system, graphing, etc. The method of data collection isn’t as important as making sure data is collected. It will be difficult to impossible to determine progress and make programming decisions without solid, accurate data. If you don’t like data collection or want to avoid taking so much data, I’d suggest a VB type program where trial by trial data is not collected. There are pros and cons to either choice; it really depends on how the child performs. For some kids you really do need to see that progression of learning, and for other children only the summary of progress is needed.
- Generalization- DTT gets a pretty bad rap when it comes to generalization. Many people think that DTT is the most robotic and boring type of ABA out there, and that it teaches skills in a vacuum (the child can answer “pig” when asked “What says oink-oink?”, but says nothing when asked “What does a pig say?”). I have stated this before on my blog, and I’ll say it again: Poor quality ABA providers perform poor quality therapy. The only reason why DTT would be lacking a plan for generalization is if the DTT program was being done improperly. I already mentioned one way that DTT can plan for generalization (vary the materials). Another method is something called “Maintenance”. This is when known skills are reviewed days, weeks, or even months after the child was taught the skill. So if my client learned to say her phone number last week, I will ask the skill again next month. The purpose of maintenance is to make sure the child retained the skill, which can be an issue for children with Autism. Failing to incorporate generalization techniques into a DTT program will only lead to problems in the long run.
**Quick Tip: For more information about Discrete Trial Teaching, check out the information below:
DTT Research Articles:
Lovaas OI (February 1987). "Behavioral treatment and normal educational and intellectual functioning in young autistic children". J Consult Clin Psychol 55 (1): 3–9
Gresham, FM & MacMillar, DL. (1998). Early intervention project: Can its claims be substantiated and its effects replicated? Journal of Autism and Developmental Disorders,28(1): 5-13
Sallows GO, Graupner TD (November 2005). "Intensive behavioral treatment for children with autism: four-year outcome and predictors". Am J Ment Retard 110 (6): 417–38.
McEachin JJ, Smith T, Lovaas OI (January 1993). "Long-term outcome for children with autism who received early intensive behavioral treatment". Am J Ment Retard 97 (4): 359–72; discussion 373–91
Suzannah Ferraioli, Carrie Hughes and Tristram Smith (2005) : A Model for Problem Solving in Discrete Trial Training for Children With Autism. JEIBI 2 (4), Pg.224- 229
Individualized Autism Intervention for Young Children: Blending Discrete Trial and Naturalistic Strategies, Travis Thompson