Dopamine, paranormal belief, and the detection of meaningful stimuli

J Cogn Neurosci. 2010 Aug;22(8):1670-81. doi: 10.1162/jocn.2009.21313.


Dopamine (DA) is suggested to improve perceptual and cognitive decisions by increasing the signal-to-noise ratio. Somewhat paradoxically, a hyperdopaminergia (arguably more accentuated in the right hemisphere) has also been implied in the genesis of unusual experiences such as hallucinations and paranormal thought. To test these opposing assumptions, we used two lateralized decision tasks, one with lexical (tapping left-hemisphere functions), the other with facial stimuli (tapping right-hemisphere functions). Participants were 40 healthy right-handed men, of whom 20 reported unusual, "paranormal" experiences and beliefs ("believers"), whereas the remaining participants were unexperienced and critical ("skeptics"). In a between-subject design, levodopa (200 mg) or placebo administration was balanced between belief groups (double-blind procedure). For each task and visual field, we calculated sensitivity (d') and response tendency (criterion) derived from signal detection theory. Results showed the typical right visual field advantage for the lexical decision task and a higher d' for verbal than facial stimuli. For the skeptics, d' was lower in the levodopa than in the placebo group. Criterion analyses revealed that believers favored false alarms over misses, whereas skeptics displayed the opposite preference. Unexpectedly, under levodopa, these decision preferences were lower in both groups. We thus infer that levodopa (1) decreases sensitivity in perceptual-cognitive decisions, but only in skeptics, and (2) makes skeptics less and believers slightly more conservative. These results stand at odd to the common view that DA generally improves signal-to-noise ratios. Paranormal ideation seems an important personality dimension and should be assessed in investigations on the detection of signals in noise.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Analysis of Variance
  • Chi-Square Distribution
  • Culture*
  • Decision Making / drug effects
  • Dopamine / metabolism*
  • Dopamine Agents / blood
  • Dopamine Agents / pharmacology
  • Double-Blind Method
  • Functional Laterality / drug effects
  • Functional Laterality / physiology
  • Humans
  • Levodopa / blood
  • Levodopa / pharmacology
  • Male
  • Motor Skills / drug effects
  • Motor Skills / physiology
  • Neuropsychological Tests
  • Paranoid Personality Disorder / psychology*
  • Pattern Recognition, Visual / drug effects
  • Pattern Recognition, Visual / physiology
  • Photic Stimulation / methods
  • Reaction Time / drug effects
  • Reaction Time / physiology
  • Signal Detection, Psychological / drug effects
  • Signal Detection, Psychological / physiology*
  • Surveys and Questionnaires
  • Thinking / drug effects
  • Thinking / physiology*
  • Visual Fields / drug effects
  • Visual Fields / physiology
  • Young Adult


  • Dopamine Agents
  • Levodopa
  • Dopamine