Positive and Negative Incentive Contrast Effects with Rats as a Function of Sex.

Experiment 1 attempted to determine if sex was a controlling factor in the production of negative contrast. The Ss were 60 male and female albino rats 68-104 days of age. In an operant conditioning chamber a saccharine solution was reduced in concentration from 1.2% to. 10% for both males and females. Only the males displayed the downward incentive effect. Experiment 2 attempted to discover if sex was a determiner of positive contrast in 60 male and female albino rats 68-104 days of age. Saccharine concentration was increased from .01% to 1.0% in an operant box for both sexed groups. Again, only the males exhibited contrast. The conclusion from the two above investigations is that the factor of sex is one controller of both the downward and upward effects.