53: When Transparency Meets Learning: Can Operant Conditioning Reinforce Open-Label Placebo Hypoalgesia?

Topic: Basic Science
Subtopic: Non-specific to any diagnosis (including studies in healthy animals), Developing methodology/technology, Placebo/Nocebo, Behavioral studies

Background and Aims: Open-label placebos (OLPs) can reduce pain despite full transparency, yet little is known about whether learning mechanisms can enhance their effects. While classical conditioning has shown promise in strengthening placebo responses, operant conditioning remains unexplored in OLP paradigms. This study investigated (1) whether operant conditioning enhances OLP-induced hypoalgesia and (2) whether openly and deceptively induced operant placebo effects are comparable in magnitude.

Methods: In a randomized experimental study (N = 102), healthy participants were assigned to four groups: Open-label placebo + operant conditioning (OLP+OC), open-label placebo only (OLP), deceptive placebo + operant conditioning (DP+OC), or natural history control. Pain was induced via electrocutaneous stimulation. During conditioning, participants could reduce pain intensity by activating an inert TENS device. Pain ratings and expectations were measured across baseline, manipulation, and testing phases. Data were analyzed using linear and generalized mixed-effects models.

Results: Across the full testing phase, no significant placebo effects were observed. However, in the first testing block, a significant placebo response emerged in the OLP group. No placebo response was found in the OLP+OC or DP+OC groups. The placebo response in the OLP group was significantly larger than in the OLP+OC group. Although open-label instructions reduced pain expectations, these changes did not consistently translate into sustained pain reduction.

Conclusions: Operant conditioning did not enhance open-label placebo hypoalgesia and may have attenuated its initial effect. These findings suggest that the efficacy of OLP may depend on procedural simplicity and internal consistency. Adding operant learning mechanisms to transparent placebo administration does not appear to increase analgesic outcomes and may interfere with openly induced placebo responses.

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Bieniek, H., Brączyk, J., Bajcar, E., Żegleń, M., Paulewicz, B., & Bąbel, P. (2025). From relief to relief and back again: Placebo hypoalgesia induced by operant conditioning with negative reinforcement.

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Presenting Author: Justyna Brączyk
Submitting Author: Justyna Braczyk

Senior Author: Przemysław Bąbel

IASP 2026 Global Year theme of Neuropathic Pain: No

• Helena Bieniek: MA - Jagiellonian University in Kraków
• Przemysław Bąbel: PhD - Jagiellonian University in Kraków