What enables "distraction" to reduce delay discounting for pigeons (Columba livia)

In a successive delay-discounting task, a small reward can be obtained immediately but a larger reward can be obtained if one waits. There is evidence that the larger reward can be obtained more easily if one is "distracted" from obtaining the small reward. It is proposed here that a distractor stimulus may function as a Pavlovian conditioned stimulus (sign tracking) because orienting to it may be directly associated with the larger reinforcer. In the present study with pigeons, we examined two successive procedures: (a) a peck to a red light resulted in one pellet of food, and waiting for the red light to turn off resulted in five pellets (Red-Only). (b) If the pigeon pecked a red light, it received one pellet of food, and if it waited for the red light to turn to green, a peck to the green light resulted in five pellets of food (Red-Green). For both groups, on some trials, a concurrent (distractor) stimulus appeared with the red light but responses to it had no programed consequence. Results indicated that the pigeons in both groups waited for the larger reward more often when the distractor was present than when it was absent and that pigeons in the Red-Only group waited longer than those in the Red-Green group. The results are consistent with the hypothesis that the concurrent stimulus served as a conditioned stimulus for the Red-Only group and as a higher order conditioned stimulus for the Red-Green group. (PsycInfo Database Record (c) 2023 APA, all rights reserved).