Effects of price, ‘openness’ of the economy and magnitude of the alternative reinforcer on responding for caffeinated coffee

Suzanne H. Mitchell, Carol L. Laurent, Harriet De Wit, James P. Zacny

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


Consumption of a commodity is influenced by various factors. This experiment examined three factors: unit price, ‘openness’ of the economy, and magnitude of an alternative reinforcer. Subjects earned caffeinated coffee and money by responding on concurrent random‐ratio (RR) schedules. Coffee price was varied by changing the coffee schedule from RR 1·3 to RR 16, while holding the money schedule constant (RR4). Openness of the economy was varied by changing the amount of unearned coffee provided during a 2‐h post‐task period (0, 1·5 or 3 free cups). The magnitude of the alternative reinforcer was varied by allowing subjects to earn an average of $2·00 or $6·00 for responding on the money schedule. Number of responses for coffee and amount of coffee earned varied inversely with the openness of the economy, but were unaffected by the amount of money available. Analysing the demand for coffee as a function of coffee price revealed that coffee was a less elastic commodity when the economy was closed than when it was more open. Within the range of parameters tested here, price of caffeinated coffee and openness of the economy strongly affected responding in humans, whereas the magnitude of an alternative monetary reinforcer had only limited effects.

Original languageEnglish (US)
Pages (from-to)39-46
Number of pages8
JournalHuman Psychopharmacology: Clinical and Experimental
Issue number1
StatePublished - 1995
Externally publishedYes


  • Behavioural economics
  • caffeine
  • coffee
  • elasticity
  • human
  • open/closed economy
  • reinforcer magnitude
  • self‐administration

ASJC Scopus subject areas

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


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