title: The processing of perceptual similarity with different features or spatial relations as revealed by P2/P300 amplitude.
abstract: Visual features such as "color" and spatial relations such as "above" or "beside" have complex effects on similarity and difference judgments. We examined the relative impact of features and spatial relations on similarity and difference judgments via ERPs in an S1-S2 paradigm. Subjects were required to compare a remembered geometric shape (S1) with a second one (S2), and made a "high" or "low" judgment of either similarity or difference in separate blocks of trials. We found three main differences that suggest that the processing of features and spatial relations engages distinct neural processes. The first difference is a P2 effect in fronto-central regions which is sensitive to the presence of a feature difference. The second difference is a P300 in centro-parietal regions that is larger for difference judgments than for similarity judgments. Finally, the P300 effect elicited by feature differences was larger relative to spatial relation differences. These results supported the view that similarity judgments involve structural alignment rather than simple feature and relation matches, and furthermore, indicate the similarity judgment could be divided into three phases: feature or relation comparison (P2), structural alignment (P3 at 300-400 ms), and categorization (P3 at 450-550 ms).
authors: Research Centre for Special Economic Zone Research, Shenzhen University, Shenzhen 518060, China; Research Centre for Brain Function and Psychological Science, Shenzhen University, Shenzhen 518060, China.
authors: Qingfei
authors: Q
authors: Chen
authors: Research Centre for Brain Function and Psychological Science, Shenzhen University, Shenzhen 518060, China.
authors: Xiuling
authors: X
authors: Liang
authors: Research Centre for Brain Function and Psychological Science, Shenzhen University, Shenzhen 518060, China.
authors: Peng
authors: P
authors: Li
authors: College of Psychology, Liaoning Normal University, Dalian 116029, China.
authors: Chun
authors: C
authors: Ye
authors: Research Centre for Brain Function and Psychological Science, Shenzhen University, Shenzhen 518060, China.
authors: Fuhong
authors: F
authors: Li
authors: Research Centre for Brain Function and Psychological Science, Shenzhen University, Shenzhen 518060, China. Electronic address: leiyi821@vip.sina.com.
authors: Yi
authors: Y
authors: Lei
authors: Research Centre for Brain Function and Psychological Science, Shenzhen University, Shenzhen 518060, China. Electronic address: lihongwrm@vip.sina.com.
authors: Hong
authors: H
authors: Li
mesh_terms: D001931:Brain Mapping; D004569:Electroencephalography; D018913:Event-Related Potentials, P300 / Q000502:physiology*; D005260:Female; D006801:Humans; D007600:Judgment / Q000502:physiology*; D008297:Male; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation; D011930:Reaction Time / Q000502:physiology; D013028:Space Perception / Q000502:physiology*; D013997:Time Factors; D055815:Young Adult
keywords: Difference judgment; ERPs; P2; P300; Similarity judgment