Multiple treatment interference occurs when the effects of one treatment are influenced by the effects of another treatment administered in the same experiment making it difficult to isolate the true impact of each individual intervention The Multielement Design also known as the Alternating Treatments Design is most susceptible to this threat In a multielement design two or more conditions eg different interventions or a baseline and an intervention are rapidly alternated often within the same session or across sessions within a short period This rapid alternation increases the likelihood that a participants behavior under one condition is affected by their recent exposure to another condition For example carryover effects from a highly reinforcing condition might influence behavior in a less reinforcing condition or behavioral contrast might occur While other designs Reversal Multiple Baseline Changing Criterion can also be affected by various threats the inherent structure of the multielement design involving concurrent or rapid sequential exposure to multiple conditions makes it particularly vulnerable to multiple treatment interference