What is DTT?
Ole Ivar Løvaas was a Norwegian-American clinical psychologist and professor at the University of California, Los Angeles. He is most well-known for his research on what is now called applied behaviour analysis (ABA) to teach autistic children through prompts, modelling, and positive reinforcement. The therapy is also noted for its former use of aversive (punishment) to reduce undesired behaviour.
In the 1970s, O. Ivar Lovaas applied behavioural principles to teach language, play, social interactions, and self-help skills to institutionalised children diagnosed with autism. Lovaas’ work at UCLA led to the development of discrete trial teaching (DTT). Unlike the free-operant format of precision teaching, in which students practise skills at their own pace, DTT is teacher-directed. The teacher determines the pace of instruction, selects the teaching stimuli, and creates consequences that are easily manipulated and controlled, but often unrelated to the teaching stimuli.
For whom it can be used?
DTT schedules consequences until the skill is established. This is a form of applied behaviour analysis focused on directly observable behaviours that can be measured and analysed to assess student learning. This is a precise and systematic method of evaluating instruction. Neither approach prescribes what should be taught or how to teach. Regardless of the behaviour analytic approach selected by teachers, the acquisition of new skills depends on the contingent delivery of reinforcers following desired behaviour. These are not competitive strategies but different applications of the same basic science.
Discrete trial training (DTT) is a method of teaching. The discrete trial method has three distinct parts: (1) the trainer’s presentation (“point to the red block”), (2) the child’s response (the child points), and (3) the consequence (correction or reinforcement). Pausing between trials can provide an opportunity for data collection. However, the pacing and length of the pause should be timed to maintain the child’s attention.
The model looks like this:
A cue to perfom some behavior that leades to a reward
Child’s action as a result of the cue
What happens following the response (i.e. a reward for correct responding)
Pause
Learning format
Compared to traditional classroom instruction, DTT teaching provides students with multiple opportunities to practise skills. The classroom teacher typically sits face to face with one or more students in a setting that minimises distractions. Additional options are acceptable. For example, DTT can also be used in a classroom, community, or home setting. When DTT is implemented in multiple environments, skills are more likely to be generalised or used in different settings. Teaching interactions begin with the presentation of a teaching stimulus (a direction or question). Correct responses are followed by the delivery of reinforcers. Errors (failure to respond or incorrect responses) are corrected and followed by the next teaching interaction. Each teaching sequence is identical to the previous one and contains a clear beginning and end. Data is pooled across teaching trials to evaluate student outcomes.
DTT procedures differ in the extent they allow errors to occur. The occurrence of errors reduces the overall frequency of reinforcement, decreases the time available for instruction, and may produce inappropriate emotional responses, including disruptive, self-injurious, or aggressive behaviour. Effective instruction creates opportunities for children to succeed without making errors. To establish control of newly acquired behaviours, it is sometimes necessary to help a child attain a reinforcer by prompting the desired response. A prompt is an additional stimulus (vocal, visual, gestural, or physical) that increases the likelihood that a discriminative stimulus will occasion the desired response. Prompts should be related to the task and should be removed as soon as the need for them no longer exists. Inadvertent, excessive, and repeated prompts should be avoided or a dependency on the prompt develops. When teaching independent tasks, care should be taken to avoid embedding prompts into the teaching procedures. Physically prompting a child through all or part of a response and then reducing manual guidance permits the errorless acquisition of a response by naturally occurring stimuli in the environment.
Evidence-base
Based upon the recent review, discrete trial training meets the evidence-based practice criteria set by the US National Professional Development Center on Autism Spectrum Disorder (NPDC) with 13 single case design studies. The practice has been effective with learners in preschool (3-5 years) to elementary school learners (6-11 years). Evidence-based practices (EBP) and studies included in the 2014 EBP report detailed how discrete trial training can be used effectively to address: social, communication, joint attention, behaviour, school-readiness, adaptive, and academic outcomes.
General remarks
Although DTT is effective in teaching children to respond correctly, critics argue that DTT creates an artificial learning environment where teachers direct trials while students learn to wait for instruction. The argument is that children taught this way do not learn to self-initiate or respond to natural cues and consequences. To become functional and spontaneous, any skill that is taught in isolation must become integrated into the context of the child’s day. Children must attend to appropriate environmental stimuli, generalise these skills and use them spontaneously. To foster acquisition and the generalisation of newly learned behaviours, teachers must bring these skills under the control of more natural contingencies.
While a useful tool, there are cons to only using discrete trial training. Generally speaking, autistic children excel in rote memorization. Massed trials of training capitalise upon this strength in children. Unfortunately, rote memorization is often confused with true understanding or comprehension. For example, a child may have memorised a story repeatedly read to them. Adults may confuse the student’s memorization of the story with true comprehension or understanding.
Autistic children have difficulty with generalisation also. If massed trials are provided using the same materials, same phrasing and in the same setting, professionals cannot be sure the child will be able to practise the skill or retrieve the knowledge with novel materials and in new settings. Generalisation and real world application should always be programmed purposefully within ABA and DTT programs.
Ultimately, the success of any strategy can be measured by how well the child performs a skill in non-instructional settings. This should be addressed in the beginning stages of any type of programming.
References
Downs, A., & Downs, R. C. (2013). Training new instructors to implement discrete trial teaching strategies with children with autism in a community-based intervention program. Focus on Autism and Other Developmental Disabilities, 28(4), 212-221. doi:10.1177/1088357612465120
Jenkins, S. R., Hirst, J. M., & DiGennaro Reed, F. D. (2015;2014;). The effects of discrete-trial training commission errors on learner outcomes: An extension. Journal of Behavioral Education, 24(2), 196-209. doi:10.1007/s10864-014-9215-7
Lerman, D. C., Hawkins, L., Hoffman, R., & Caccavale, M. (2013). Training adults with an autism spectrum disorder to conduct discrete-trial training for young children with autism: A pilot study. Journal of Applied Behavior Analysis, 46(2), 465-478. doi:10.1002/jaba.50
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