Reinforcing Effects of Stimulants in Humans: Sensitivity of Progressive-Ratio Schedules

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43 Scopus citations


Drug self-administration methodologies have been developed for use in humans to model naturalistic stimulant drug-taking behaviors. These methodologies use a number of schedules of reinforcement, including progressive-ratio schedules. As the name implies, in a progressive-ratio schedule, the response requirement for each subsequent delivery of drug increases, and the primary outcome variable is often the break point (i.e., the last ratio completed to receive a drug delivery). These schedules have been used in a number of human laboratory studies evaluating the reinforcing effects of stimulants. The results of these studies have demonstrated that progressive-ratio schedules are sensitive to manipulation of a pharmacological variable, dose, and to nonpharmacological variables contributing to stimulant drug effects. In addition, findings with progressive-ratio schedules are largely concordant with clinical findings, suggesting that drug self-administration under these schedules has predictive validity in terms of drug abuse and dependence. Future research is necessary, however, to understand better how pharmacological factors like route of administration, onset of effects, and pretreatment influence the reinforcing effects of stimulants under progressive-ratio schedules.

Original languageEnglish
Pages (from-to)503-512
Number of pages10
JournalExperimental and Clinical Psychopharmacology
Issue number6
StatePublished - Dec 2008


  • drug reinforcement
  • humans
  • progressive ratio
  • stimulant

ASJC Scopus subject areas

  • Pharmacology
  • Psychiatry and Mental health
  • Pharmacology (medical)


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