Transfer of control in ambiguous discriminations.

Rats' acquisition and transfer of performance in ambiguous discriminations was examined using discrete-trial operant lever-press procedures. Rats learned serial ambiguous discriminations (X----A+, A-; B+, X----B-) by acquiring both positive and negative occasion setting functions to the X feature. Mutual transfer occurred among cues from serial ambiguous, feature positive (Y----C+, C-), and feature negative (Y----C-, C+) discriminations, but that transfer did not extend to cues not trained within one of those serial discriminations. The ambiguous feature's positive occasion setting powers were unaffected by nonreinforced presentation of that feature alone, and posttraining counterconditioning did not eliminate the feature's ability to serve as a negative occasion setter. Occasion setting was not acquired with simultaneous ambiguous discriminations (XA+, A-; XB-, B+), which apparently were solved with a configural strategy.