Preweanling and adult rats treat conditioned light-tone combinations differently

Philipp J. Kraemer, Norman E. Spear

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


Ontogenetic differences in processing light-tone compounds were discovered in preweanling (17-day-old) and adult (60-80-day-old) rats. Suppression of general activity was used as an index of the magnitude of conditioned fear following a single training session in which a CS+ was paired with mild footshock. In Experiment 1, rats were trained on discriminations in which the CS- consisted of a light and the CS+ was either a tone alone (simple discrimination) or a light-tone compound (simultaneous feature-positive discrimination). Adults and preweanlings given each type of discrimination were then tested for fear of the CS- and a target stimulus (tone alone or light-tone compound). Adults in all groups displayed greater fear of the target than of the CS-. Preweanlings, however, discriminated the CS- from the target only when the target was the same as the original CS+. Experiment 2 revealed that age-related differences in conventional stimulus generalization is not a likely explanation for the pattern of results found in Experiment 1. Experiment 3 revealed age-related differences in expressed fear of a serial feature-positive discrimination; adults, but not preweanlings, showed greater fear of the compound than of the CS-. Alternative interpretations of the results from these experiments are discussed, and the general conclusion is that adults appear more inclined to process elements of a compound stimulus selectively, whereas preweanlings seem more likely to process the compound unselectively, with roughly equivalent processing of each element.

Original languageEnglish
Pages (from-to)113-123
Number of pages11
JournalAnimal Learning and Behavior
Issue number2
StatePublished - Jun 1990

ASJC Scopus subject areas

  • Neuropsychology and Physiological Psychology
  • Experimental and Cognitive Psychology
  • Animal Science and Zoology
  • Psychology (all)
  • Behavioral Neuroscience


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