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Meeting Point: Latest From Lovaas

September 07

Meeting Point: Latest From Lovaas

Why Discrete Trials Work

As a consultant I have observed many parents, teachers, and other professionals in teaching situations with children with autism, and I am sometimes struck by how some may say they disagree with discrete trial teaching while at the same time teach in a fashion that is quite similar. To a certain extent this makes sense as discrete trial teaching is based on common sense.

A discrete trial consists of three components: 1) the teacher's instruction, 2) the child's response (or lack of response) to the instruction, and 3) the consequence, which is the teacher's reaction in the form of positive reinforcement, "Yes, great!" when the response is correct, or a gentle "no" if it is incorrect.

Here is an example of a discrete trail in a classroom setting. The teacher asks, "What sound does the letter F make?" The child answers, "ffff", and the teacher praises the child. Incorrect responses are also followed by immediate feedback. For example, if the child answers "mmm," the teacher says, "No, can someone else tell me?" Or, the teacher says, "No, but try again. What sound does the letter F make?" This time she helps the child by stretching out the sound, thus suggesting the correct answer.

A teacher might teach through a series of almost discrete trials without even knowing it. But because the procedure they use is incomplete, I have observed many instances where the child with autism made little or no progress.


Discrete trials work partly because the procedure embraces the idea of reinforcement as "anything" that motivates the child to learn. When a child with autism learns a new behavior, this behavior must be practiced numerous times before it is completely mastered and in layman's terms, reinforcement is anything that increases the likelihood that a behavior will occur again. A young child with autism does not have the knowledge or the experience yet to appreciate praise and we must go the extra mile to find that extra special something that will make him or her practice and learn.

Discrete trial teaching typically starts with using anything that is reinforcing, be it toys, foods, activities, things hidden in a kitchen cupboard, a bracelet from a sister's jewelry box, a tie from a father's closet, even a set of car keys as long as it motivates the child to learn. However, we always gradually and systematically work toward presenting more natural reinforcement.

Concise Language

Typically-developing children gradually learn their native language seemingly without much structure or breakdown of grammar or words, mostly helped along by listening, imitating and practicing, all day long. Most children with autism need a different approach. They need structured lessons with the language broken down into small, simple and clear components that only gradually may be chained together into finished and grammatically correct sentences. With this information in mind, we look at a child with autism who has reached the stage where he is taught several language programs concurrently, such as verbal imitation of simple words, receptive (i.e., non-verbal) labeling of objects and receptive instructions (e.g., "wave," "clap," "jump" and "walk"). It should not be difficult to appreciate that instructions limited to the most important words only will facilitate learning at this point. For example, if a child is taught to discriminate between two objects displayed on the floor, such as a toy truck versus the doll Elmo, the instructor may hold out her hand and say, "truck" rather than "give me truck," "touch truck," or "where is the truck?" The elimination of the extra words facilitates the discrimination. The difference in sound when hearing "truck" versus "Elmo" is clear and distinct whereas the instructions "Give me truck" versus "Give me Elmo" begin with the same two words, "Give me," which may easily camouflage the object labels the child is asked to differentiate. Furthermore, how would we know what part of the sentence the child is attending to when the sentence has more than one word?

Visual Cues

Those unfamiliar with discrete trials will often ask, "But how does a child know to pick up the truck when all you say is 'truck'?" The way the child is supposed to proceed is often conveyed as much through visual cues as through spoken language and, in the above example, the instructor held out her hand and said, "truck." With some initial hand-over-hand help the child learns that when the instructor holds out her hand, he or she is supposed to put something in that hand. Later, when the instructor holds up the truck and says, "truck," a child can learn, again with some appropriate help, that he or she is supposed to repeat (i.e., imitate) what the instructor said. The words "give me..." or "say..." are not necessary to clarify what the child is asked to do, in fact, the added language may confuse the child. We often take for granted that all the words in an instruction are meaningful to a child when, in fact, most early learners with autism will require systematic discrimination learning to understand their meaning. Since many children with autism have strong visual abilities, stronger than auditory, the emphasis on visual cues is often helpful.

Quick Responding

In discrete trial teaching, a question or instruction is clearly and distinctly presented once, and the child is typically required to respond within three seconds. Otherwise the response is considered to be a lack of a response or a non-response, which is also considered an incorrect response. As the beginning of a response can be quite subtle, such as when visually scanning among a number of pictures displayed on a table, the instructor must be observant and attentive of the child in order to teach correctly and keep the child successful.

Quick responding to instructions is required in the discrete trial procedure and the child is taught this skill. Parents will quite often tell me that they have been told that their child has a "processing delay" causing him or her to be slow to respond. While I would not completely disregard the notion of "processing delays," I cannot ignore the numerous times I have experienced that a child has learned to respond quickly with a simple prompt and prompt fading technique. It could cause a serious delay in a child's learning process to take an assumption of "processing delay" for granted. It is tempting to speculate that in some cases, maybe most, it might be a person's inadequate training in effectively teaching children with autism that prompts this "processing delay" "diagnosis."

Learning to respond quickly is important because it helps the child stay focused and attentive and keeps him or her from defaulting to self-stimulatory behaviors, or other inattentive behaviors.

Clear Consequences

In everyday life it is not uncommon for someone to repeat an instruction over and over until it is followed. My wife tells me that when she was little, she knew that if her mom called her for dinner, she did not really have to come in until the third time she was called because it was not until the fourth time that her mom would come get her and she would be in trouble. Likewise, when instructions or questions are repeated over and over without taking time to require a response before presenting the next repetition, a child with autism learn that responding the first time is not necessary, and it becomes harder and harder to obtain his or her attention. In discrete trial teaching, every single question or instruction presented has an immediate and clear consequence and if a child responds correctly, a reinforcer is immediately given (again, anything that increases the likelihood that the child will respond). If a child responds incorrectly (or is non-responsive), the instructor gently says, "no," (and withholds the reinforcer) then repeats the instruction, and if necessary provides a prompt to help the child respond correctly and receive the reinforcer (See Errorless Learning below).

Errorless Learning

Errorless learning is secured for the child when the instructor employs various prompting strategies in her teaching procedure. Prompting is an essential component in discrete trial teaching and is instrumental in the process of shaping new behavior.

It is assumed that children with autism have failed to understand what well-meaning adults, including their parents, have tried to communicate. Consequently, they have experienced continuous failure and, understandably, react with frustration, avoidance of eye contract, with tantrums or other attempts to escape or avoid future failure. Every effort is therefore made to create a teaching situation in which the child does not experience failure, does not make mistakes, but is successful through errorless learning. We can accomplish this by immediately helping/prompting the child to respond correctly to an instruction. This prompt is systematically reduced or faded over time until the child knows how to respond independently.

In the beginning of a child's intervention program we want the child to experience success with every single response and provide all the prompts necessary to this end. As the child feels more confident and has learned the basic behaviors, we make every effort to keep the child successful at least 80 percent of the time throughout the remainder of his or her intervention program.

Prompting Hierarchy

Prompting the child through a response is a planned procedure and carried out gradually and systematically, and prompts typically range from most to least intrusive where hand-over-hand prompts are considered the most intrusive and a subtle visual cue the least intrusive prompt. In discrete trial teaching, removing or fading a prompt is not as simple as just dropping it. The instructor must know how and when to fade from one form of prompting to another, making the prompt less and less intrusive until the child is able to respond correctly on his or her own. For example, if a child is learning to imitate the instructor as she is waving her hand, the instructor may simultaneously prompt the child to wave by physically guiding the child's hand through the motion. Over the next number of trials the instructor gradually decreases the degree of the hand-over-hand prompt to simply touching the child's hand briefly, then fades to just pointing to the child's hand, and if necessary, the last prompt might be just looking at the child's hand with a subtle nod of the head. Eventually no prompt is needed at all.

Determining in the moment the least intrusive prompt that will lead toward independent responding and not to prompt-dependency is part of the dynamic process involved in discrete trial teaching.

The names of all children in this newsletter have been changed in respect for family confidentiality.

From the Editor

Here again are some of the letters to the editor we have received recently. We will continue to take your requests into consideration when planning future articles. If you have insight into any of the requests, based on your own experience, feel free to forward your comments to us as well. I look forward to continuing our discussion next month.

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On the Lighter Side...
...5 outrageous reinforcers sure to add fun in therapy

Foot Flying! The child sits on your foot and you fly him high. Then say, "it's Barney's turn" and make Barney fly on your foot, then the child again.

Silly Telephone Calls! Make a ringing noise and pick up the telephone and say, "It's for you, (child)!" Add silly praise dialog. Alternatively, say that you've got to call Mickey Mouse and when talking to him praise the child's performance.


The First Hour of Trent's Intervention Program

In March 2007, four days after his second birthday, Trent, who had been diagnosed at a very early age with Pervasive Developmental Disability, Not Otherwise Specified, PDD(NOS), began receiving Family-directed services supervised by Jennifer, a consultant at the Lovaas Institute.

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