Event-Related Potential Correlates of Two Stages of Information Processing in Physical and Semantic Discrimination Tasks


  • This research was supported by grants HD 10804 and MH 06723 from the USPHS. We would like to acknowledge the many helpful comments of Drs. Daniel Ruchkin, Samuel Sutton and Nancy Squires. We would also like to thank Chester Freeman for electronic assistance and Anita Levine and Linda Murphy for preparation of the manuscript.

Address requests for reprints to: Dr. Walter Ritter, Department of Neuroscience, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461.


Event-related potentials were studied while subjects performed physical and semantic discrimination tasks. Two negative components, NA and N2, were observed in both kinds of discriminations. The earlier component, NA, had a constant onset latency, but its peak latency varied as a function of stimulus complexity. N2 latency varied in relation to changes in the peak of NA. RT and P3 followed N2 by similar amounts of time across tasks. The NA and N2 components were interpreted as reflecting partially overlapping sequential stages of processing associated with pattern recognition and stimulus classification, respectively.