Discrimination learning as a function of varying pairs of sucrose rewards.

Abstract

Five groups of rats were trained in a Y maze using a combination of free-and forced-choice trials to equate number of Rs to each arm. Sucrose reward was present in both arms, but in different concentrations. In terms of the solutions received, the groups were: 2%-4%, 4%-8%, 8%-16%, 16%-32%, 32%-64%. Principal results were: discrimination occurred in both choice and starting-speed measures and the degree to which Ss discriminated in one measure correlated significantly with degree of discrimination in the other; running speed appeared to be a negatively accelerated, exponential function of sucrose concentration; optimal discrimination occurred for intermediate pairs of concentrations. These results were in accord with implications derived from Spence''s interpretation of incentive motivation.