The effect of a longer fixed- and variable-duration CS on operant responding

Abstract

A light was associated with fixed-time (FT), variable-time (VT), fixed-interval (FI), or variable-interval (VI) schedules. With FT, the light was terminated after 50 sec and a response-independent food pellet was presented. With VT, the duration of the light varied about a mean value of 50 sec. With FI, the first response emitted after 50 sec produced a food pellet. With VI, the interval was varied about a mean value of 50 sec. These schedules were presented intermittently, and operant responding was maintained on a VI schedule in the absence of the light. The FT and VT schedules produced facilitation of operant responding. The FI and VI schedules also produced facilitation of operant responding, but there was no difference in the rate between FT and FI and between VT and VI.