Differential outcome effects in pavlovian biconditional and ambiguous occasion setting tasks

Abstract

Three experiments with rats explored the differential outcome effect (DOE) using a pavlovian magazine approach conditioning preparation. Experiment 1 compared groups trained on a biconditional discrimination (AX+, AY-, BX-, BY+) with differential or nondifferential outcomes, and Experiment 2 examined this using an ambiguous occasion setting task (e.g., AX+, X-, Y+, AY-). In both experiments, subjects trained with differential outcomes learned the tasks better than subjects trained with nondifferential outcomes. Furthermore, subjects given differential outcome training learned the positive occasion setting component of the ambiguous task more efficiently than the negative occasion setting component, although both were enhanced by differential outcome training. Experiment 3 demonstrated that the ambiguous occasion setting task was reversed more readily when the target-outcome relations (as opposed to the modulator-outcome relations) were maintained during the reversal phase. These data suggest that an acquired distinctiveness effect may be responsible for the DOE in pavlovian learning.

Figure 1

Mean magazine responding over 4-session blocks of biconditional discrimination training for groups receiving differential (Gp Diff) and nondifferential (Gp Nondiff) reinforcement in Experiment 1. Data are shown separately in the pre stimulus periods (Pre), as well as collapsed over reinforced (CS+) and nonreinforced (CS−) trials.

Figure 2

Mean magazine responding over 4-session blocks of training on the ambiguous cue occasion setting task for groups receiving differential (Gp Differential) and nondifferential (Gp Non Differential) reinforcement in Experiment 2. Data are shown separately in the pre stimulus periods (Pre, Pre A), as well as to the target stimuli (X, Y) in the presence and absence of the feature stimulus (A). + and * denote reinforcement by different outcomes and – indicates nonreinforcement.

Figure 3

Experimental design used in Experiment 3. The target stimuli (X, Y) were followed by (->) one of two reinforcing outcomes (US1, US2) in the presence or absence of the feature stimulus (A). The contingencies were reversed during the reversal phase either by maintaining the target-US or the modulator-US relations.

Figure 4

Mean magazine responding over 4-session blocks of training and reversal on the ambiguous cue occasion setting task in Experiment 4. Data are shown separately in the pre stimulus periods (A (Pre), No A (Pre)), as well as to the target stimuli (X, Y) in the presence and absence of the feature stimulus (A). + and * denote reinforcement by different outcomes and – indicates nonreinforcement. The first symbol before the / indicates the outcome presented during acquisition and the second symbol after the / indicates the outcome presented during the reversal phase.