Mand Transfer Trials as a Time Delay Process

In the preceding section we discussed the form of various prompts that can be used to insure that the student emits the desired topography of mand behavior. In our discussion we suggested the use of transfer trials to fade prompts and to promote independent manding. The actual process of using transfer trials will involve some additional information. The term “transfer trial” refers to a rapid procedure for transferring stimulus control from the prompted to the unprompted condition in programs of instruction involving discrete trials. In simple terms we need to be able to help the student emit the response and then quickly remove that help so the student asks independently. We remove the help by waiting for a little while before prompting in order to encourage an independent response.

Remember that when prompts are delivered immediately and do not allow the student to make an error, they are termed 0 second time delay prompts.

Here is some basic information on implementing time delay procedures.

Steps to Implement Time Delay Procedure (Wolery, Ault, and Doyle, 1992)

• Identify the stimulus (prompt) that cues the student to respond
• Assess the student’s ability to wait for a prompt
• Identify the number of 0 second time delay prompt trials to be used
• Identify the length of prompt delay interval for transfer trials
• Determine the consequences based on student responding for successful performance with and without prompting
• Implement, monitor, and adjust program based on student performance and data patterns.

As this chart indicates, the time delay between the presentation of the desired item and the prompt is held constant. When initially teaching a mand, a 0 second time delay prompt is used. In other words when the reinforcer is shown to the child and thus signals it is available and the student demonstrates motivation to obtain the reinforcer, the instructor immediately prompts the response.

Remember, the term “transfer trial” refers to a rapid procedure for transferring stimulus control from the prompted to the unprompted condition in programs of instruction involving discrete trials. Transfer trials with verbal operant training involve the use of recency effects: any behavior that has just been reinforced is more likely to occur than other behaviors in the period following its reinforcement. Thus a successful prompt with a 0 second delay will make responding with a longer time delay more likely.

In order to fade the response, the next step is to begin shifting from the errorless process of immediate prompting to a prompt fade interval. To accomplish this, the instructor puts in place a different rule regarding prompt timing. Basically, the instructor waits a little while in order to see if the student will emit the mand without prompts. If the student fails to emit the mand after a longer time delay, for instance from 3 to 5 seconds, the instructor then provides a prompt to ensure that the mand occurs and can be reinforced. Because motivation to emit the mand must build for students, the time delay period can be set for intervals of up to 5 or more seconds depending on the student’s pattern of responding. The time delay allows transfer of operant control for the mand from the prompted to an unprompted condition. However, the instructor will need to monitor the student during the time delay interval. If the student emits an error in the interval it may be likely that the student will require a greater number of consecutive immediate prompted mand trials or other procedures to reduce scrolling.

Decisions to increase the interval of time delay can be made based on the consistency of accurate student manding. The time delay used for any specific mand may vary. If a student exhibits stronger motivation to receive an item, the instructor may be able to use a longer time delay interval.

Steps in Using Time Delay Procedures for Prompting Mands

• Wait for child to show motivation (capture or contrive)
• Model and pair mand form and reinforcer delivery (say it and/or sign it as you deliver the item)
• Prompt the mand with a 0 second time delay
• Deliver reinforcer as child emits prompted response
• Re-present item and pause 5 seconds, if spontaneous mand occurs, deliver reinforcer, if not and child is reaching for item, prompt mand response and deliver reinforcer (this is a transfer trial)
• If error occurs in time delay period, use error correction procedures outlined for each response form
• Increase time delay interval with success of independent responses