Previous studies that used theoddball paradigm indicated that N2 is sensitive to perceptual novelty of visual targets [8], and our results indicatedthat Close/Fast icons induced the highest N2 amplitude. Thissuggests that target icons with close semantic distance wereeasier to recognize (as targets) because they had more visualcues (novelty) related to their target functions than far iconsdid. Moreover, this novelty effect became significant underfast presenting-speed conditions.