ROLE OF DIFFERENTIAL SAMPLE RESPONDING IN THE DIFFERENTIAL OUTCOMES EFFECT INVOLVING DELAYED MATCHING BY PIGEONS

The role of differential sample responding in the differential outcome s effect was examined. In Experiment 1, we trained pigeons on a one-to -many matching task with differential sample responding required. Diff erential outcomes were associated with samples and comparisons, with c omparisons only, or with neither samples nor comparisons. Slopes of de lay functions for trials with pecked versus nonpecked samples suggeste d use of a single-code-default strategy in the nondifferential-outcome s group but not in the differential-outcomes groups. In Experiment 2, differential sample responding and differential outcomes were manipula ted independently. Again, there were significant differences in the re lative slopes of the delay functions. Results suggest that differentia l outcomes exert their effect independently of differential sample res ponding.