Mirror, mirror on the wall: placebo effects that exist only in the eye of the beholder
Bibliographic record
Abstract
Rationale The extent to which placebo effects can be driven exclusively by subjective impressions of improvement in the absence of any independent corroboration is unclear. Methods Thirty-six self-referred patients were treated with a light therapy device intended to rejuvenate facial skin. At each of eight weekly treatments, participants' facial skin was exposed for 40 seconds to pulses of multispectral LED-generated light in the range of 588 nm wavelength at 0.1 J cm(-2). Outcomes were assessed by participants as well as by the treating doctor and by blinded, expert raters. Results Patients reported robust and statistically significant improvements in seven facial features at the conclusion of the 8-week treatment regimen as well as at 1-month follow-up (for all comparisons, P </= 0.003, median d = 1.14). In sharp contrast, both the treating doctor and blinded, expert raters were unable to detect any improvement whatsoever (for all comparisons, P > 0.05). Moreover, effect sizes were close to zero and in the opposite direction from improvement (median d = -0.06 for doctor ratings; and for observer ratings, there was only a 46% success rate at identifying post-treatment as compared with pre-treatment photographs). Conclusion The robust placebo responses documented in this trial were confined to the subjective impressions of the patients. Neither the treating doctor nor blinded, expert raters could detect any improvement. Thus, patients can perceive improvement in medical interventions in the absence of any independent corroboration that improvement has occurred. This result is used a heuristic to more clearly define the components of the placebo response.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.006 | 0.012 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.002 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".