The timing of CNV resolution in a memory retrieval task.

Twelve men performed the Sternberg memory retrieval task while the EEG and EOG were recorded. Subjects saw a target set of 1 to 4 digits followed by a warning tone that was followed after 1.5 sec by a probe digit. Subjects indicated by pressing one of two levers whether the probe digit was in or out of the target set. The timing of contingent negative variation (CNV) resolution was measured as the latency of 50% resolution in stimulus-synchronized waveforms (SSWs), response-synchronized waveforms (RSWs), and model waveforms (MWs). The MWs were constructed by adding each RSW to itself using time displacements derived from the reaction times of the single trials of which the RSW was an average. The results indicated that CNV resolution is related to the timing of the motor response. MWs had resolution latencies close to those of the SSWs. In SSWs the N1 and P3 to the warning tone also varied with target set size.