| Abstract: | A recently developed mathematical model (DMOD) also predicts that Ss prefer the unpredictable reward situation under conditions that substantially decrease aversiveness of unpredictable nonreward (Daly & Daly, 1982). Because a high proportion of reinforced trials (lenient schedule) and alcohol decrease aversive conditioning, these variables were tested with rats in 5 E-maze experiments. A choice to 1 side of the maze resulted in a stimulus uncorrelated with reward outcome (unpredictable). A choice to the other side resulted in stimuli correlated with reward and nonreward (predictable). Stimuli were not visible until after the choice was made. A lenient reinforcement schedule resulted in preference for the unpredictable reward situation if rewards were not delayed. Alcohol resulted in preference for the unpredictable reward situation if a medium 5-pellet reward was given. A lenient reinforcement schedule combined with an alcohol injection resulted in faster acquisition of the preference for the unpredictable reward situation than did a lenient schedule combined with a saline control injection. These results pose a major challenge to most theories, yet were predicted by DMOD. (PsycINFO Database Record (c) 2010 APA, all rights reserved) |
