Learned irrelevance: No more than the sum of CS and US preexposure effects?

In the Ist experiment, 1 group of rats (Group Learned Irrelevance [LIRR]) experienced uncorrelated presentations of a noise and shock; a 2nd group (Group Control [CON]) experienced noise and shock in separate phases of training. Six conditioning sessions followed, each consisting of a single noise-shock pairing. Group LIRR conditioned to the noise more quickly than Group CON. The 2nd experiment was identical to the Ist, except that rats were given 6 noise-shock pairings in each conditioning session. In this experiment, Group LIRR learned more slowly than Group CON. These results suggest that learned irrelevance is in part the product of context specificity of latent inhibition, in which the context is the aftereffect of shock presentation. The implications of this for theories of learned irrelevance are discussed.