The Effect Of Shifts In Fixed-Interval Schedules On Acquisition,Extinction, Spontaneous Recovery,And Reacquisition

Using both multivariate and univariate statistical tests, the effect of two opposite patterns of primary reinforcement schedules upon the acquisition, extinction, spontaneous recovery and reacquisition of bar pressing was determined. Two control and two experimental groups, each consisting of eight Ss, formed the standard 2x2 factorial design for the experiment. The main effects were (a) effect of primary reinforcement (experimental vs. control groups) and (b) direction of shift in the schedule values (ascending vs. descending groups). The extinction data showed that the experimental group exposed to the ascending-order shift pressed the bar more than the descending group. Therefore, persistence of nonreinforced responding is a function of the direction of shift in fixed-interval values. The recovery data for first day indicated that primary reinforcements following either pattern facilitated spontaneous recovery. However, on second day neither direction of shift nor primary reinforcement had any significant effect on it. Covariance analysis of recovery and reacquisition data for second day revealed that the experimental ascending group showed better recovery and reacquisition when the frequency of prior nonreinforced responding was held constant. The SL analyses suggest a higher acquisition level for the experimental ascending group than for the other groups. It is possible to explain the result in terms of Hull's habit- strength theory.