From the perspective of the Fuzzy Trace Theory, this study investigated the impacts of concept maps with two strategic orientations (comprehensive and thematic representations) on readers' performance of cognitive operations (such as perception, verbatim memory, gist reasoning and syntheses) while the readers were reading two history articles that argue from different perspectives about a historical incident that had a profound impact on Taiwan. The results show that the design and focus of the concept maps may influence the formation of mental representations, and that this may be facilitative or constraining in regard to the readers' memory formation and reasoning about the reading materials. Based on these findings, the meaning of constraining effects of concept maps is discussed, and an instructional method involving the progressive elaboration of concept map systems is recommended.