Effects of an open-label placebo on divergent thinking performance

Placebos deceptively labeled as "creativity enhancers" have been shown to improve divergent thinking (DT) performance. This study examined whether nondeceptive placebos administered with full transparency, which are also known as open-label placebos (OLPs) can produce comparable effects when framed as enhancing either cognitive or affective processes.

Participants were randomly assigned to one of three groups that completed the Alternative Uses Task (AUT) twice within a single testing session. After the first AUT (baseline), two groups received a placebo pill, which was introduced either as a "creativity enhancer" or a "mood enhancer", whereas the third group received no treatment. Objective outcomes included DT performance (fluency, originality, and flexibility); subjective measures comprised ratings of mood, attention, performance perception, and expected/perceived placebo efficacy.

The study included 105 participants (mean age: 29.6 years, SD = 9.63, 62% female). Placebo administration improved subjective outcomes but did not affect DT performance (all p > 0.05). It increased self-reported mood (ΔM = 0.36, 95% CI [0.13, 0.58], SE = 0.11) and attention (ΔM = 0.56, 95% CI [0.27, 0.84], SE = 0.14), regardless of labeling condition. Perceived placebo efficacy after the AUT decreased relative to expected efficacy before the experiment (ΔM = -0.66, 95% CI [-1.07, -0.25], SE = 0.21).

These placebo effects were limited to subjective states and were comparable across the creativity- and mood-enhancement suggestion conditions, highlighting the need for future research to further investigate the role of content-specific suggestions in placebo responsiveness.