Trial reportPloS one2017
Classical conditioning without verbal suggestions elicits placebo analgesia and nocebo hyperalgesia.
Trial report in PloS one, 2017. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 39 papers.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
39 citing papers in PubMed, 84 citations in OpenAlex.
- Trial
- Roles of administration route, expectation, and belief in placebos in a randomized controlled trial with open-label placebos.Scientific reports · 2025Trial
- Trial
- Open-label placebos enhance test performance and reduce anxiety in learner drivers: a randomized controlled trial.Scientific reports · 2024Trial
- Learning mechanisms in nocebo hyperalgesia: the role of conditioning and extinction processes.Pain · 2020Trial
- Placebo analgesia induced by verbal suggestion in the context of experimentally induced fear and anxiety.PloS one · 2019Trial
- Article
- Article
- Negative expectations and related nocebo effects in shoulder pain: a perspective for clinicians and researchers.Pain management · 2025Review
- The Two Sides of Placebo Analgesia: Differential Functional Connectivity Reveals Mechanisms of Placebo Analgesic Response.Journal of pain research · 2025Article
- Clinical neuroscience and neurobiology of placebo and nocebo effects.International review of neurobiology · 2025Review
- Differential neural activity predicts the long-term stability of the effects of positive and negative expectations on pain.Scientific reports · 2024Article
- The Nocebo Effect.Annual review of pharmacology and toxicology · 2024Review
- Placebo hypoalgesia induced by operant conditioning: a comparative study on the effects of verbal, token-based, and social rewards and punishers.Scientific reports · 2023Article
- Placebo effects in functional dyspepsia: Causes and implications for clinical trials.Neurogastroenterology and motility · 2023Review
- The neglect of sex: A call to action for including sex as a biological variable in placebo and nocebo research.Contemporary clinical trials · 2022Review
- The placebo and nocebo effects in functional urology.Nature reviews. Urology · 2022Review
- Placebo and nocebo effects in youth: subjective thermal discomfort can be modulated by a conditioning paradigm utilizing mental states of low and high self-efficacy.British journal of pain · 2022Article
- Counterconditioning as Treatment to Reduce Nocebo Effects in Persistent Physical Symptoms: Treatment Protocol and Study Design.Frontiers in psychology · 2022Article
- Expectations: How and when do they contribute to placebo analgesia?Frontiers in psychiatry · 2022Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
7 authors at 2 institutions in 3 countries.
Funding
No grant is acknowledged in the PubMed record.
Abstract
The aim of this study was to examine the relationships among classical conditioning, expectancy, and fear in placebo analgesia and nocebo hyperalgesia. A total of 42 healthy volunteers were randomly assigned to three groups: placebo, nocebo, and control. They received 96 electrical stimuli, preceded by either orange or blue lights. A hidden conditioning procedure, in which participants were not informed about the meaning of coloured lights, was performed in the placebo and nocebo groups. Light of one colour was paired with pain stimuli of moderate intensity (control stimuli), and light of the other colour was paired with either nonpainful stimuli (in the placebo group) or painful stimuli of high intensity (in the nocebo group). In the control group, both colour lights were followed by control stimuli of moderate intensity without any conditioning procedure. Participants rated pain intensity, expectancy of pain intensity, and fear. In the testing phase, when both of the coloured lights were followed by identical moderate pain stimuli, we found a significant analgesic effect in the placebo group, and a significant hyperalgesic effect in the nocebo group. Neither expectancy nor fear ratings predicted placebo analgesia or nocebo hyperalgesia. It appears that a hidden conditioning procedure, without any explicit verbal suggestions, elicits placebo and nocebo effects, however we found no evidence that these effects are predicted by either expectancy or fear. These results suggest that classical conditioning may be a distinct mechanism for placebo and nocebo effects.
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What OpenQuestion holds
Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.