Unequal associative changes when excitors and neutral stimuli are conditioned in compound.

In four experiments a compound of a previously conditioned excitor and a neutral stimulus was either reinforced with food or nonreinforced. Two experiments used a magazine approach procedure in rats, and two used an autoshaping procedure in pigeons. All experiments employed a novel compound test procedure, which permitted evaluation of the size of the associative change that took place for the excitatory and neutral stimuli. Reinforcement of the compound resulted in greater increments in the associative strength of the neutral stimulus than of the excitor. Nonreinforcement of the compound resulted in greater decrements in the associative strength of the excitor than of the neutral stimulus. These results agree with earlier experiments with compounds of excitors and inhibitors and provide an additional challenge to contemporary error-correction models of conditioning.