Second-order conditioning detects unexpressed morphine-induced salt aversion

Rick A. Bevins, Timothy A. Delzer, Michael T. Bardo

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


Morphine failed to condition a salt taste aversion at a dose (15 mg/kg) sufficient to produce a robust aversion to a saccharin taste. Indeed, three different concentrations of salt (1%, 1.5%, and 2%) paired with the same morphine dose yielded no direct evidence for conditioned aversion. Yet, when a novel saccharin taste was paired in compound with the previously conditioned salt conditioned stimulus, we found evidence for a conditioning to the saccharin cue alone in three separate experiments. Control groups eliminated alternative accounts such as neophobia and differential exposure to morphine. Combined, these findings indicate that morphine conditioned a salt aversion. Although this aversion was not directly expressed, a second- order conditioning procedure was able to provide a more sensitive index of conditioning.

Original languageEnglish
Pages (from-to)221-229
Number of pages9
JournalAnimal Learning and Behavior
Issue number2
StatePublished - May 1996

ASJC Scopus subject areas

  • Neuropsychology and Physiological Psychology
  • Experimental and Cognitive Psychology
  • Animal Science and Zoology
  • General Psychology
  • Behavioral Neuroscience


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