Table 1 Testing schedule for probabilistic choice task. Subjects were trained and tested according to the schedule shown here. Initial pre- and postoperative testing was conducted with the probability of large reinforcer delivery declining across trial blocks from 1 to 0.0625 (the steps were p = 1, 0.5, 0.25, 0.125, and 0.0625). Subsequently, subjects were tested alternating between the hungry and sated state (as described in the Methods), before the reinforcement probabilities were manipulated further, as indicated.
Sessions | Description | Probability (small reward of 1 pellet) | Probability (large reward of 4 pellets) |
|---|---|---|---|
1–12 | Preoperative training (12 sessions) | p = 1 | p = 1 to 0.0625, decreasing |
- | Surgery and recovery | - | - |
13–24 | Postoperative baseline testing (12 sessions) | p = 1 | p = 1 to 0.0625, decreasing |
25–28 | Satiety tests (4 sessions) | p = 1 | p = 1 to 0.0625, decreasing |
29–34 | Equal probabilities, certain (6 sessions) | p = 1 | p = 1 |
35–46 | Increasing probabilities (12 sessions) | p = 1 | p = 0.0625 to 1, increasing |
47–52 | Large reinforcer always very unlikely (6 sessions) | p = 1 | p = 0.0625 |