Effects of the hallucinogen psilocybin on covert orienting of visual attention in humans

Neuropsychobiology. 2002;45(4):205-12. doi: 10.1159/000063672.


Hallucinogenic drug-induced states are considered as models for acute schizophrenic disorders (experimental psychoses). In a double-blind study with healthy volunteers we investigated the influence of the serotonergic hallucinogen psilocybin, the ecstasy-like drug 3,4-methylenedioxyethylamphetamine (MDE), the stimulant d- methamphetamine and placebo on covert orienting of spatial attention (n = 8 in each group). Reaction times were prolonged after ingestion of psilocybin > MDE, but not after d-methamphetamine. In addition, subjects on psilocybin exhibited particularly slow reaction times in invalid trials at short cue target intervals and failure of response inhibition in valid trials at long cue target intervals for right visual field targets. Despite some methodological limitations, these results are in line with both bilateral impairment of disengagement of attention and a lateralized impairment of inhibition of return (IOR) in productive psychotic states. Additional investigations with larger samples, different hallucinogenic substances (serotonergic agonists vs. NMDA antagonists) and different dose regimens are needed in order to further explore the suggested relationship between visuospatial attentional dysfunction and acute psychotic conditions.

Publication types

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

MeSH terms

  • 3,4-Methylenedioxyamphetamine / adverse effects
  • 3,4-Methylenedioxyamphetamine / analogs & derivatives*
  • Adult
  • Attention / drug effects*
  • Central Nervous System Stimulants / adverse effects
  • Double-Blind Method
  • Female
  • Hallucinogens / adverse effects*
  • Hallucinogens / pharmacology
  • Humans
  • Male
  • Methamphetamine / adverse effects
  • Middle Aged
  • Psilocybin / adverse effects*
  • Psilocybin / pharmacology
  • Reaction Time
  • Space Perception / drug effects*
  • Visual Perception / drug effects*


  • Central Nervous System Stimulants
  • Hallucinogens
  • Psilocybin
  • Methamphetamine
  • 3,4-Methylenedioxyamphetamine
  • 3,4-methylenedioxyethamphetamine