Modification of Component Preference on a Multiple Variable Interval Variable Time Schedule: Implications for Chronic Welfare Dependency

Abstract

During choice testing, 20 rats obtained food pellets by leverpressing on a variable interval (VI) or obtained them freely on a variable time (VT) schedule. Alternation of schedule components occurred when a rat emitted a changeover response on one of the two response levers in the chamber. Rats which had 20 days access to the changeover lever before testing (Group C-C-C) showed a very strong preference for the VT component during the 10-day choice period. Rats which received 20 days of VI training before access to the changeover lever showed a strong preference for the VI component. Rats which received primarily free food for 10 days, were then given 10 days of VI training only, showed a preference for the VT component but this preference was significantly less than that of Group C-C-C.