Runway Performance as a Function of Magnitude of Runway Reward and Intertrial Reinforcement

Rats were trained to traverse a straight alley for either 1 or 10 food pellets as reward. Each runway trial was preceded by an intertrial reinforcement of 1 or 10 pellets. A negative contrast effect obtained and persisted throughout the 72 trials conducted. Although there was a strong suggestion of a positive contrast effect throughout training, the effect did not prove reliable. The contrast effect results were interpreted as challenging the view that with extended training ITRs become “irrelevant” to runway reward.

Influence of Consecutive Small-Reward Trials and Intertrial Reinforcements in the Varied Magnitude of Reinforcement Experiment

2 varied magnitude of reward instrumental runway studies with rats were conducted to ascertain whether the sequential variables, intertrial reinforcements and number of successive small magnitude of reward trials (S-length) would influence resistance to extinction (Rn) in a manner similar to that of comparable variables in the partial reinforcement (PR) situation. Exp. I indicated that S-length affects Rn in the same manner as the number of consecutive nonreinforced trials in the PR experiment. Contrary to the results of PR experiments, in Exps. I and II, the intertrial reinforcement procedure did not reduce Rn. The results of the two experiments indicate, however, that animals receiving identical goal events but differing in the sequence of such events exhibit differential Rn.