Shifts in magnitude of reinforcement: Confounded factors or contrast effects?

Abstract

An empirical examination of contrast effects reported to be produced by upshifts and downshifts in magnitude of reinforcement revealed that (1) body weight differences develop during preshift training as a function of differential magnitudes of reinforcement under a 23-hr deprivation schedule, (2) these weight differences are confounded with the shift in magnitude of reinforcement, and (3) the confounded weight differences are both necessary and sufficient for the contrast effects reported by G. Collier and M. H. Marx (see 34:2). (PsycINFO Database Record (c) 2006 APA, all rights reserved)