Final answer:
The ABAB and multiple treatment reversal designs in experimental psychology are prone to sequence effects, which occur when the influence of prior conditions affects behavior in later conditions.
Step-by-step explanation:
When discussing reversal designs in the context of experimental psychology, two types which are known to suffer from sequence effects are the ABAB design (also known as a reversal or withdraw design) and the multiple treatment reversal design. Sequence effects occur when the impact of a prior condition influences the subject's behavior in subsequent conditions. In the case of the ABAB design, which involves an initial baseline (A), an intervention (B), a return to baseline (A), and a reinstatement of the intervention (B), sequence effects can manifest as changes in the subject's behavior that result from the repetitive exposure to treatment and withdrawal instead of the treatment itself.
The multiple treatment reversal design, where more than one treatment is tested in succession, can also produce sequence effects. For example, the effects of the first treatment may carry over and influence the efficacy or response to the second treatment. This can make it difficult to discern the unique impact of each treatment when analyzing the outcomes.