Stimulus-response learning in long-term cocaine users: Acquired equivalence and probabilistic category learning

Nehal P. Vadhan, Catherine E. Myers, Eric Rubin, Daphna Shohamy, Richard W. Foltin, Mark A. Gluck

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


Objective: The purpose of this study was to examine stimulus-response (S-R) learning in active cocaine users. Participants and methods: Twenty-two cocaine-dependent participants (20 males and 2 females) and 21 non-drug using control participants (19 males and 2 females) who were similar in age and education were administered two computerized learning tasks. The Acquired Equivalence task initially requires learning of simple antecedent-consequent discriminations, but later requires generalization of this learning when the stimuli are presented in novel recombinations. The Weather Prediction task requires the prediction of a dichotomous outcome based on different stimuli combinations when the stimuli predict the outcome only probabilistically. Results: On the Acquired Equivalence task, cocaine users made significantly more errors than control participants when required to learn new discriminations while maintaining previously learned discriminations, but performed similarly to controls when required to generalize this learning. No group differences were seen on the Weather Prediction task. Conclusions: Cocaine users' learning of stimulus discriminations under conflicting response demands was impaired, but their ability to generalize this learning once they achieved criterion was intact. This performance pattern is consistent with other laboratory studies of long-term cocaine users that demonstrated that established learning interfered with new learning on incremental learning tasks, relative to healthy controls, and may reflect altered dopamine transmission in the basal ganglia of long-term cocaine users.

Original languageEnglish (US)
Pages (from-to)155-162
Number of pages8
JournalDrug and Alcohol Dependence
Issue number1-2
StatePublished - Jan 11 2008

All Science Journal Classification (ASJC) codes

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


  • Basal ganglia
  • Cocaine
  • Dopamine
  • Habit learning
  • Hippocampus
  • Learning transfer
  • Procedural learning
  • Stimulus-response learning

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