ERPs elicited by a cognitive incongruity paradigm:: a semantic memory study

The cognitive incongruity paradigm consists in presenting congruous or incongruous factual information to subjects, who are instructed to judge the truth of this information by comparing it with the factual knowledge stored in their semantic long-term memory. The factual information tested was whether a city presented after the name of a country, belongs (congruity) or not (incongruity) to that country. Results revealed that the recognition of incongruous factual information is characterized by a negative wave (N400), while the processing of congruous factual knowledge is characterized by a positive wave (P300) about 600 ms post-stimulus. In addition, these two components were sensitive to subject performance and subject confidence levels. The neurophysiological brain pattern observed during the cognitive incongruity paradigm reveals that the N400 and P300 are jointly affected by the task and reflect the recognition processes of factual knowledge. NeuroReport 11:977-981 (C) 2000 Lippincott Williams & Wilkins.