Some sources of variation in the bar-pressing versus freeloading phenomenon in rats.

Gave 40 albino rats a choice between barpressing for food or taking it freely from a dish. In Exp I Ss were given 3 days of free-food training and 6 days of barpress training before the choice. In Exp II the number of prechoice bar presses was varied within the choice sessions, and in Exp. III the choice sessions were extended over 10 days. In all 3 experiments the mean number of pellets obtained via bar pressing was over 70%. In Exp IV and V the amount of time spent and the number of pellets obtained in freeloading and barpressing were equalized. In both studies Ss greatly preferred to freeload. (PsycINFO Database Record (c) 2010 APA, all rights reserved)