Two experiments with humans showed the extinction of contingency judgments, in a diagnostic task. Experiment 2 according with RescorlaWagner’s model, found that extinction of a cue was lesser when this cue was extinguished in compound with a previously extinguished cue. This effect according this model is due to the increase of the difference (l – SVT) in the extinction phase of the first cue. That is, an extinguished CS can provide protection from extinction to another CS, this finding suggests inhibitory properties in the extinction of causality judgments. Key words: Extinction, inhibition, causality judgments, Rescorla-Wagner model, humans.