Multiple treatment interference in the alternating treatments design as a function of the intercomponent interval length.
Space alternating treatment conditions at least two hours apart to keep the data clean.
01Research in Context
What this study did
Two boys with intellectual disability took part. Each boy had two treatments tested on the same day. One treatment targeted toy mouthing. The other targeted noncompliance.
The sessions switched back and forth every five minutes. The team varied the gap between switches. Gaps were 1 minute, 30 minutes, or 2 hours. They watched to see if the boys still responded to the right treatment.
What they found
When the gap was only 1 minute, the boys mixed up the treatments. Good behavior in one session carried into the next. This is called multiple-treatment interference.
A 2-hour gap fixed the problem. The boys now showed clear, separate changes for each treatment. The 30-minute gap helped a little, but 2 hours gave clean data every time.
How this fits with other research
Barnes et al. (1990) later built on this idea. They created the sequential alternating treatments design. They used long gaps up front when a no-treatment baseline is unsafe. Both papers agree: spacing matters.
Knutson et al. (2019) used the same rapid-switch plan with kids with autism. They kept the 2-hour spacing rule. Their skill-teaching results stayed clear, showing the rule works across populations.
Pierce et al. (1994) looked tiny gaps of 5 s versus 20 s in high-p request sequences. They found shorter gaps worked better. That seems opposite, but the tasks were simple and quick. The 1987 study used full treatments, so longer gaps were needed.
Why it matters
If you run an alternating treatments design, mark your calendar for 2-hour breaks. Clean separation lets you pick the best intervention faster. You avoid the headache of guessing whether change came from Treatment A or leftover B. Next time you compare two meds, teaching styles, or reinforcers, space them 120 minutes apart and watch the data tell a clear story.
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02At a glance
03Original abstract
In experimental designs requiring the administration of more than one treatment to the same subject(s), the effect of one treatment may be influenced by the effect of another treatment (Campbell & Stanley, 1963), a phenomenon known as multiple treatment interference. We conducted two studies in which multiple treatment interference in an alternating treatments design was shown to be a function of the length of the intercomponent interval (ICI) separating treatment conditions. In the first study, we evaluated the effects of four different treatments on the mouthing of a severely retarded boy. Under a 1-min ICI no consistent differential responding to treatment was obtained. Differential responding emerged when the ICI was increased from 1 min to 120 min, thus suggesting multiple treatment interference in the lack of differential responding under a 1-min changeover interval. Functional control of the nondifferential and differential responding as a function of the ICI length was replicated in a reversal phase. In the second study, we compared two treatment procedures for the disruptive noncompliant behavior of a moderately retarded boy. Multiple treatment interference (i.e., the lack of differential responding) occurred with the 1-min intercomponent interval. An increase to a 120-min ICI again resulted in differential responding. A replication of multiple treatment interference by a reversal to a short interval phase was not achieved in the second subject. Results of this study support much of the basic literature on discrimination and multiple treatment interference.(ABSTRACT TRUNCATED AT 250 WORDS)
Journal of applied behavior analysis, 1987 · doi:10.1901/jaba.1987.20-171