A signal detection theory analysis of the placebo effect

Eval Health Prof. 2002 Dec;25(4):410-20. doi: 10.1177/0163278702238054.


Some instances of the placebo effect may be understood as a particular type of error made by the patient--a false positive error. False positive errors are common (indeed, frequently encouraged) in medical decision making, both by diagnosticians and by patients, and are the inevitable consequence of concluding that an ambiguous signal (e.g., attenuation of pain, relief of depression) did, or did not, occur. Signal detection theory (SDT) was developed to model errors in the detection of ambiguous signals. The authors use SDT to understand the false positive errors that might be made by patients administered a placebo and termed a placebo effect.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Decision Making
  • False Positive Reactions*
  • Humans
  • Models, Psychological
  • Placebo Effect*
  • Signal Detection, Psychological*