Open-Label Placebo Cognitive Training May Be Ineffective for Cognitive Improvement

Abstract

Recent research suggests that deception is not required to elicit placebo effects. So-called “open-label” placebos are honestly given placebo treatments with beneficial effects, primarily on self-report outcomes. In a randomized control trial, I used open-label placebo cognitive training to try and improve cognitive performance. The strengths of the experiment come from a large sample, matched protocols across conditions, and the inclusion of relevant constructs to test mechanistic explanations. However, no effects were observed on either objective or subjective outcomes as a result of the open-label placebo treatment. There were some unexpected performance differences between participants recruited from a flyer advertising the brain-training component of the study, compared to participants recruited from a control flyer. The results of the primary hypotheses (open-label placebo effectiveness) may reflect a true null result, an ineffective manipulation, or noise from an overly complex experiment. The main conclusion is that some skepticism towards the generalizability of open-label placebo effects is warranted. I discuss if that conclusion stems from the current failure of the effect to replicate or from acknowledging the design components that may have caused its failure.