EXTENDED ACQUISITION TRAINING AND RESISTANCE TO EXTINCTION.

Abstract

A group of rats receiving 184 food rewarded, runway acquisition trials extinguished faster than groups receiving only 64 acquisition trials. This was found to be the case whether or not the groups receiving different numbers of acquisition trials were equated prior to extinction with respect to such variables as age, amount of handling, and length of time on deprivation schedule. The results corroborate previous findings by North and Stimmel on the effects of extended acquisition training, and indicate that their results cannot be attributed simply to the age, handling, and deprivation variables. It is a commonly held position, supported by a variety of studies (e.g., Perin, 1942; Williams, 1938), that resistance to extinction in an instrumental reward situation is an increasing monotonic function of the number of acquisition trials. A recent investigation, however, provides evidence that extended acquisition training can lead to decreased resistance to extinction. North and Stimmel (1960) found that rats given 90 or 135 acquisition trials in a straight runway extinguished faster than rats given 45 acquisition trials. The design of this experiment, however, was such that the various groups started training at the same time, and consequently started extinction at different times. Hence, such variables as age, amount of handling, and length of time on deprivation schedule before extinction were confounded with number of acquisition trials. The present study was designed to evaluate the importance of these variables in studies of overlearning, as well as to determine the reproducibility of the effect reported by North and Stimmel.