Combinations of response-dependent and response-independent schedule-correlated stimulus presentation in an observing procedure

Anthony DeFulio, Timothy D. Hackenberg

Research output: Contribution to journalArticle


Pigeons pecked a response key on a variable-interval (VI) schedule, in which responses produced food every 40 s, on average. These VI periods, or components, alternated in irregular fashion with extinction components in which food was unavailable. Pecks on a second (observing) key briefly produced exteroceptive stimuli (houselight flashes) correlated with the component schedule currently in effect. Across conditions within a phase, the dependency between observing and presentation of the stimuli was decreased systematically while the density of stimulus presentation was held constant. Across phases, the proportion of session time spent in the VI component was adjusted from 0.5 to 0.25, and then to 0.75. Results indicate that rate of observing decreased as the dependency between responses and stimulus presentations was decreased. Further, discriminative control by the schedule-correlated stimuli was systematically weakened as dependency was decreased. Increasing the proportion of session time spent in VI decreased the rate of observing. This effect was additive with the manipulation of the dependency between observing and presentation of the stimuli. Overall, these results show that conditioned reinforcers function similarly to unconditioned reinforcers with respect to response-consequence dependencies, and that stimulus control is enhanced under conditions in which the relevant stimuli are produced by an organism's behavior.

Original languageEnglish (US)
Pages (from-to)299-309
Number of pages11
JournalJournal of the Experimental Analysis of Behavior
Issue number3
StatePublished - May 2008



  • Brief stimuli
  • Concurrent operants
  • Conditioned reinforcement
  • Discriminative stimulus
  • Key peck
  • Observing
  • Pigeon
  • Response-independent schedules

ASJC Scopus subject areas

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

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