title: The effects of direction similarity in visual working memory: Behavioural and event-related potential studies.
abstract: Object similarity can improve visual working memory (VWM) performance in the change-detection task, but impair the recognition performance when it occurs at retrieval of VWM in the recognition task. The effect of direction similarity is an issue that has not been well resolved. Furthermore, electrophysiological evidence in support of the mechanisms that underlie the effects of similarity is still scarce. In the current study, we conducted three behavioural experiments to examine the effects of direction similarity on memory performance with regard to both the encoding and retrieval phases of VWM and one event-related potential (ERP) experiment to explore the neural signatures of direction similarity in VWM. Our behavioural studies indicated that direction similarity improved performance when it occurred at the encoding phase but impaired performance when it occurred at the retrieval phase. Moreover, the ERP experiment showed that the amplitude of the contralateral delay activity (CDA) increased with the increasing set size for similar but not dissimilar directions. In addition, the CDA amplitude for similar directions was lower than that for dissimilar directions at set size 2. Taken together, these findings suggest that direction similarity at encoding has a positive effect on VWM performance and at retrieval has a negative effect. Given that VWM capacity depends on information load and the number of objects, the positive effect of similarity may be attributed to reduced information load of memory objects.
authors.affiliation: a Department of Psychology , Shandong Normal University, Key Laboratory of Human Cognition and Behavioural Development of Shandong High School , Jinan , China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: a Department of Psychology , Shandong Normal University, Key Laboratory of Human Cognition and Behavioural Development of Shandong High School , Jinan , China.
authors.forename: Shouxin
authors.initials: S
authors.lastname: Li
authors.affiliation: b Key Laboratory of Animal Resistance of Shandong Province, Department of Anatomy and Physiology , College of Life Science, Shandong Normal University , Jinan , China.
authors.forename: Xiusong
authors.initials: X
authors.lastname: Wang
authors.affiliation: a Department of Psychology , Shandong Normal University, Key Laboratory of Human Cognition and Behavioural Development of Shandong High School , Jinan , China.
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Che
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001288:Attention / Q000502:physiology; D003463:Cues; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D009949:Orientation / Q000502:physiology*; D010775:Photic Stimulation; D011930:Reaction Time / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult
keywords: Contralateral delay activity; Direction similarity; Information load; Visual working memory