Papini, Mauricio R.2016-12-202016-12-2020162016https://repository.tcu.edu/handle/116099117/12269This research was designed in search of symmetry between positive and negative contrast effects (SPC and SNC, respectively). Previous research has shown outcome devaluation of one lever in autoshaping to result in increased responding to a second lever that had been associated with a smaller, consistent reward. The present study replicated these results in a series of occasional free-choice trials, and provided evidence for the positive contrast effect following an unexpected upshift in one lever. A subgroup of animals that received a downshift first showed SNC, and went on to demonstrate SPC when faced with an upshift later in training. Alternatively, a second subgroup who received an upshift first failed to show SPC, or SNC when they experienced a downshift in the next phase. These results provide evidence for asymmetry between SNC and SPC, and suggest the possibility that experiencing frustration is necessary for the behavioral expression of elation.Format: OnlineNo search engine accessText