EVENT-RELATED POTENTIAL SCALP FIELDS DURING PARALLEL AND SERIAL VISUAL SEARCHES

Event-related potential (ERP) scalp fields generated during parallel a nd serial searches were compared using a bootstrap resampling techniqu e. Two different parallel search tasks required the detection of a sin gle feature either color or orientation. A serial search task required the detection of the feature conjunction target: color and orientatio n. Identical stimuli were used for both parallel searches and a simila r stimulus for the serial search. No evidence for scalp field differen ces earlier than 150 ms were discovered, suggesting that 'low-level' v isual processing is the same in both types of searches. ERP scalp fiel ds that distinguished parallel from serial searches were identified be tween 150 and 250 ms. It is proposed that these different scalp fields represent timing and/or magnitude differences in the regions of corte x activated during parallel and serial searches.