CONTINGENCY THEORY AND THE EFFECT OF THE DURATION OF SIGNALS FOR NONCONTINGENT REINFORCEMENT

Rats learned to approach a light that signaled food when food occurred only after the signal, but did not approach the light when food was e qually probable regardless of the signal. When food unpaired with the light was preceded by a 5-sec noise, little learning was evident as we ll, but when the unpaired food was preceded by a 15-sec noise, approac h to the light conditioned stimulus readily occurred. These effects of signal duration are similar to those previously obtained with the eff ect of free food on free-operant behavior and challenge existing theor ies of contingency effects in Pavlovian conditioning.