Evaluation of the relation between Pavlovian occasion-setting and instrumental discriminative stimuli: a blocking...

Experiments with rat subjects used a blocking design (A+, then AB+) to assess the relation between Pavlovian occasion-setting and instrumental discriminative stimuli. Prior conditioning of both associative and occasion-setting functions of A in a serial feature-positive procedure blocked acquisition of an instrumental discriminative function by a novel stimulus (B) trained in compound with A. However, neither prior conditioning of only an A-US (unconditioned stimulus) association nor prior conditioning of Stimulus A using a Pavlovian simultaneous feature-positive procedure, which does not endow A with an occasion-setting function, blocked acquisition of an instrumental discriminative function by B. Prior acquisition of an instrumental discriminative function by A blocked acquisition of a Pavlovian occasion-setting function by a novel stimulus (B) trained in compound with A, but did not block acquisition of an association between B and the US. These outcomes indicate that Pavlovian occasion-setting and instrumental discriminative properties of a stimulus are functionally equivalent and that both Pavlovian occasion-setting and instrumental discriminative properties of a stimulus are functionally independent of simple associative relations between that stimulus and other events.