The Overshadowing and Blocking of Punishment

Two experiments were undertaken to test the assumption that the outcome of an instrumental contingency depends on the acquisition of signalling properties by the response in the same sense that the acquisition of signalling properties by a stimulus is viewed as determining the outcome of a Pavlovian contingency. The presence coincident with a punished response of a stimulus either previously or preferentially correlated with shock was found to reduce the extent to which punishment suppressed the rate of responding. It was argued that these results, interpreted as indicating the blocking and overshadowing of the response-shock association, were consistent with the assumption tested.