The CNV and semantic content of stimuli in the experimental paradigm: Effects of feedback

Abstract

The usual contingent negative variation (CNV) paradigm S 1S 2R was modified by requiring a discrimination at S 2 and by adding a feedback stimulus: S 1S dΔR…..FB. It was demonstrated that as the discrimination task became more difficult and therefore the feedback (FB) more important informationally, the CNV became prolonged until the FB signal and the amplitude of the evoked response to this stimulus increased in size. It is suggested that the discharge of a CNV occurs at the time of significant informational feedback. In the normal CNV paradigm this is usually intrinsic in S 2 and R, but in a discrimination task it may be delayed to an explicit feedback stimulus. The FB evoked response changes reinforce the concept that the amplitude of at least some components of an evoked response reflect the psychological significance of the stimulus. Psychiatric patients, including five schizophrenics, showed changes similar to those observed in normals, but the patient data were unusable because of significant contimination by EOG and galvanic skin response artifact.