A test of sex differences in instrumental appetitive learning by rats

A total of 48 laboratory rats, half male and half female, were trained and extinguished on instrumental bar-pressing for either 16% or 64% sucrose incentives. No consistent sex differences were found in either acquisition or variability of bar-press responding, or in extinction. The only statistically reliable difference indicated that males were more variable in responding for the 16% sucrose incentive, as measured by the range of scores over each week. It is concluded that no real sex differences in learning proficiency obtain under the experimental conditions employed, and that therefore the practice of using mainly or exclusively female rats in our laboratory is methodologically sound.