1. A Direct Test of Contrast and Delay Reduction Hypotheses: Why Do Pigeons Prefer Stimuli Following Aversive Events? Rebecca Singer & Thomas Zentall University of Kentucky

2. Justification of Effort Greater value is placed on the reward that requires greater effort to obtain (i.e., A in organic chemistry vs. A in golf)

3. Justification of Effort in Pigeons Clement, Feltus, Kaiser, and Zentall (2000) FR1 + FR20 + or? Train Test

4. Contrast Effect Proposed contrast hypothesis (rather than cognitive dissonance) to explain results Value V -ΔV +ΔV Reinforcement FR1 FR20 Aversiveness of task Relative Value of Reinforcer

5. Delay Reduction Hypothesis Fantino (1969) Any stimulus that is associated with a reduction in the delay to reinforcement should become a conditional appetitive stimulus

6. Delay Reduction Hypothesis Reinforcement FR20 FR1 Presentation of discriminative stimuli

7. Overall Purpose Purpose of current experiments is to provide a direct test of the delay reduction hypothesis by holding trial duration constant Used two schedules of reinforcement: fixed interval (FI) and differential reinforcement of other behavior (DRO)

8. Experiment 1a – Training White Horiz Vert Food DRO FI Left key = DRO 20 s Right key = FI 20 s

9. Experiment 1a – Test Horiz Vert Food DRO FI White

10. Experiment 1a - Results 2 birds demonstrated DRO preference 1 bird demonstrated FI preference 4 birds demonstrated side preference

11. Experiment 1b: Purpose Contrast hypothesis states that pigeons will prefer stimuli associated with their non- preferred schedule (or side) Delay reduction hypothesis states if trial duration is equated there should be no preference for discriminative stimuli

12. Experiment 1b – Training White Horiz Vert Food DROFI

13. Experiment 1b – Test DRO, FI, or no initial event Both S+

14. Experiment 1b - Results

15. Conclusions There was no systematic schedule preference when FI and DRO schedules were used There was a significant preference for stimuli that followed the aversive schedule