Schedules of Reward Shift in the Double Runway

Eighty food deprived rats received 62 trials in a double runway. On Trials 1–30, reward in the first goal box (GB1) was either always two food pellets or always zero pellets. All subjects received two pellets in the second goal box (GB2). On Trials 31–62 subjects in each preshift group (GB1 reward or GB1 nonreward) were shifted to the opposite GB1 reward level on 0, 25, 50, 75 or 100% of occasions. GB2 reward remained unaltered in all cases. For subjects experiencing reward decrease, second runway (A2) run and goal speeds after nonreward were generally enhanced, both within-group and in comparison with never rewarded controls. No such effect was evident on A2 start speed, nor was there any evidence to suggest that A2 performance after decreased reward was a function of the schedule of decrease. Increased GB1 reward resulted in general within-group impairment of A2 start and run speeds, with no effect on A2 goal performance. However, comparisons of speeds after increased reward with those of always rewarded controls revealed no difference on A2 start or run but indicated impairment of A2 goal performance. With the 50% schedule of reward increase, A2 run speeds after nonreward (the training level) exceeded those of never rewarded controls. Results are discussed with reference to McHose's contrast account of double runway phenomena and Amsel's frustration theory.

Role of Restricted Running and Goal-Box Placements in the Double Runway Behavior of the Albino Rat

7 groups ( ns = 10) of albino rats received 40 acquisition trials (5/day) in a double alley under one of the following conditions: (1) 40 8-pellet rewarded GB1 placements; (2) 40 8-pellet rewarded run trials, RW1 and RW2; (3) 40 NR GB1 placements; (4) 40 8-pellet rewarded RW1-only trials, and (5) 40 NR run trials, RW1 and RW2. Following preshift training, 30 postshift trials were given under the following conditions: (1) one of the 8-pellet rewarded placements groups was shifted to NR, whereas the two remaining placement groups received the same GB1 conditions as in the preshift phase; all Ss in the 3 placement groups now ran RW2 only; (2) Ss in RW1-only group received 30 NR trials in GB1 and now ran RW1 and RW2; and (3) one group of eight-pellet rewarded Ss RW1 and RW. received 30 NR trials GB1, whereas the other two RW1 and RW2 groups remained as in the preshift phase. All Ss received one pellet in GB2. During acquisition, RW1 speeds were a direct positive function of GB1 magnitude, while RW2 speeds were an inverse function of amount received in GB1. The data are more supportive of a hypothesis based upon an odor-mediated, conditioned tendency to remain in GB1 rather than an emotionally based FE.