Effects of delaying food availability contingent on ethanol-maintained lever pressing

The effects of delaying food availability 8 s contingent on every, every second, and every fourth lever press maintained by 4,8, and 16% (v/v) ethanol solutions were examined when food was initially available to rats on a fixed-interval 26-s schedule. The delay contingency decreased ethanol-maintained responding at all ethanol concentrations, with the degree of decrease inversely related to the intermittency of the delay schedule and to the ethanol concentration. Such decreases were not evident in the performance of yoked-control animals which received food coincidentally with experimental animals. Temporal changes in food presentation alone therefore could not account for the decreases produced by the delay contingency.