Guest Blog Post by Dr. Katherine May, Ed.D., BCBA

Sequence Effects vs. Multiple Treatment Interference

Sequence effects occur when the effects of an intervention from one condition carry over into the next condition. Sequence effects are typically the result of a multiple treatment reversal design or a B-A-B reversal design. Sequence effects can skew the data in the following condition because the data is not going to display an accurate depiction of what is really happening. In order to reduce this you would need to continue to take data until the sequence effects subside. The experimental design used to minimize sequence effects would be an alternating treatment design where all treatments are running independently and simultaneously. It is important to note that minimizing sequence effects is an advantage of using an alternating treatment design whereas a disadvantage of using an alternating treatment design would be multiple treatment interference. This is always an issue with alternating treatment designs because of the unnatural nature of switching between multiple treatments. Multiple treatment interference is when the effects of one treatment on a subject’s behavior are being confounding by the influence of another treatment administered in the same study. This means that one treatment is affecting the other as the treatments are being alternated, not from a previous condition but instead, during the process of alternating or switching between 2-4 behaviors.

The main difference:

As stated above, the main difference between the two concepts is that with sequence effects are when the effects of an intervention are affecting the next condition whereas with multiple treatment interference the effects of one treatment on a subject’s behavior are being confounding (so let’s say confused) by the influence of another treatment. In simpler terms; sequence effects are when a treatment is affected by a previous condition and multiple treatment interference is when the treatments are affected by interference between treatments. With multiple treatment interference the treatments are interfering with each other and thus making it difficult to see which intervention is the most effective. Furthermore; sequence effects are specific to  reversal designs while multiple treatment interference is specific to alternating treatment designs.


Cooper, J. O., Heron, T. E., & Heward, W. L. (2019). Applied Behavior Analysis (3rd Edition). Hoboken, NJ: Pearson Education.

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