In order to determine the interval of the time delay between the emission of an error mand and the presentation of the next trial, several factors should be considered. One is the student’s probability of engaging in problem behavior. For students who may engage in problem behavior, you may want to start with a shorter interval of about 3 seconds but remember to increase that interval as the student gains the ability to wait. For most students, especially those who have acquired many mands, the interval can be set at 5 to 10 seconds.

Another consideration in the error correction process involves differential reinforcement. If a student emits an error response and then is prompted to emit the correct response, less reinforcement should be delivered than if the student emits the correct mand without prompts. Always remember to give better reinforcement for independent responding.

There will be times where the error correction procedures we just mentioned are not effective in reducing the rate of scrolling. At such times a more formal approach to teaching mand discrimination may be needed. Here are the procedures for running a mand discrimination program to reduce scrolling. These procedures have been adopted from the work of Dr. Vince Carbone (Carbone, 2005).

The goal of the procedures is to bring topographies of mands under the control of the appropriate stimuli, namely the item and the MO, without evoking a plethora of other mand responses.

Step one involves conducting a probe of the target mand responses and noting the occurrence of scrolled responses. To do this:

• Have all reinforcers available across many motivational categories.
• List the reinforcers on the discrimination data sheet
• Probe for Motivation: Begin the 1st probe (cold probe) by offering the reinforcer (i.e., hold it up, place it to the learner’s mouth, place it in the learner’s hand, etc) in such a way that the learner demonstrates motivation for the item (e.g., grabs for the item, looks at the item, etc) but will have a reduced inclination to scroll or sign at all.
  • If the learner should immediately demonstrate motivation move on to probe for correct topography as described below.
  • If the learner does not demonstrate motivation for the reinforcer within 8 seconds, withdraw it, record “No MO” on the data sheet, and offer the next reinforcer listed on the data sheet. You can probe again later in the session if you think the MO may be strong now.
  • If the learner begins to scroll during this probe for motivation, guide the learner’s hands in a neutral position. With the hands now in a neutral position change the presentation of the reinforcer so that the learner’s inclination to scroll is reduced (e.g., hold it up, place it to the learner’s mouth, place it in the learner’s hand, etc). If the learner does demonstrate appropriate motivation without scrolling at this point move on to the step to probe for correct topography.
  • If the learner correctly signs for the reinforcer, deliver the reinforcer, and record “yes” on the data sheet. When this occurs there is no need to probe for correct topography.
  • Present the next reinforcer listed on the data sheet.
• Probe for topography:
  • Withdraw the reinforcer
  • Record “NR” for no response on the data sheet
  • Offer the next reinforcer listed on your data sheet.

Once all the probes are completed for each reinforcer you will be ready to begin the teaching session. Here are the steps to be used in this process:

• For each presentation of the reinforcer check for an MO as described above.
• Rotate the presentation of reinforcers across both motivational and topographical classes.
• Use the least amount of prompting necessary and therefore teach near errorlessly.
• Fade prompts appropriately.
• Try not to conduct more than 3 consecutive teaching trials of the same reinforcer.
• Teaching can occur both in the NET and at the table.

When the teaching session is completed the instructor can complete a probe of the student’s manding without the procedures in place. This will involve repeating the probe that was completed in the first phase of the session.

Finally, the results of the probes will need to be graphed:

• Graph the percentage of all “1st” probes scored as “yes”.
• Graph the percentage of all “Last” probes scored as “yes”
• When calculating the percentage of both probes do not include “No Mo” in the denominator.