Analysis of information processing stages using event-related potentials.

The event-related potential (ERP) was recorded to identify the time epochs during which different independent variables have their effects on stages in a memory search task. Stimulus intensity, memory set size and response type were varied. For the most part, the order and timing of effects (evaluated by Principal Components Analysis of within-subjects ERP differences) were consistent with the presumed underlying stages, except for early effects of response type prior to memory set effects (suggesting precategorical target recognition). The usefulness of this type of analysis for the investigation of information processing stages is discussed.