Within-subjects assessment of the within-compound associations resulting from intermixed and blocked preexposure schedules

Nonhungry rats received training consisting of intermixed presentations of a compound flavor and an element of that compound (AX, X, AX, X, . . .), and then a separate block of presentations of another compound (BX, BX, BX, . . .). Stimuli A and B were two odor solutions (almond and vanilla), and stimulus X was a highly concentrated solution of sucrose. After training, a state of hunger was induced in the rats, and their consumption levels of A and B alone were tested. We found higher test consumption of B than of A (Exp. 1). We interpreted these differences as indicating that the B–X association had become stronger than the A–X association as a result of the training. In Experiment 2, we demonstrated that the presence of X during training was necessary for that effect to appear (Exp. 2). These results give support to the recent proposal that within-compound associations are maintained better by blocked than by intermixed preexposure (Rodríguez & Alonso, 2014). We discuss the implications of this difference for explaining the intermixed–blocked perceptual-learning effect.