The contingent negative variation: its relation to feedback and expectant attention.

Abstract A paradigm for the study of slow waves was used in which an attempt was made to differentiate between effects attributable to expectant attention and those attributable to intention to respond. This was a accomplished by making a discriminative response which occurred at S 2 contingent on information carried in S 1 , and by giving feedback information about accuracy of the response by means of a third stimulus, S 3 . Each of the stimuli occurred successively and were separated by approximately 1 second. Two variations of this method were used; (a) a procedure in which the third stimulus was always present before instructions as to its meaning and (b) a procedure in which the third stimulus was absent, after which was added the third stimulus and instructions about its meaning. The data indicated that surface negativity was sustained during periods when the subjects were waiting for feedback although there was no intention to respond. This occurred even when there were no instructions as to the meaning of the stimulus when subjects characteristically attempted to decode its meaning. The results were interpreted to suggest that negativity was sustained during periods of unconfounded expectant attention. It was also suggested that sustained negativity sometimes seen in cases of behavior pathology, when a standard CNV paradigm is used, may be attributable to the attempt of subjects to continue processing information relative to the response after S 2 and the response has occurred.