title: Neural activity reveals perceptual grouping in working memory.
abstract: There is extensive evidence that the contralateral delay activity (CDA), a scalp recorded event-related brain potential, provides a reliable index of the number of objects held in visual working memory. Here we present evidence that the CDA not only indexes visual object working memory, but also the number of locations held in spatial working memory. In addition, we demonstrate that the CDA can be predictably modulated by the type of encoding strategy employed. When individual locations were held in working memory, the pattern of CDA modulation mimicked previous findings for visual object working memory. Specifically, CDA amplitude increased monotonically until working memory capacity was reached. However, when participants were instructed to group individual locations to form a constellation, the CDA was prolonged and reached an asymptote at two locations. This result provides neural evidence for the formation of a unitary representation of multiple spatial locations.
authors.affiliation: Cognitive and Behavioral Neuroscience Program, Department of Psychology, George Mason University, United States.
authors.forename: Laura R
authors.initials: LR
authors.lastname: Rabbitt
authors.affiliation: Human Factors and Applied Cognition Program, Department of Psychology, George Mason University, United States.
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Roberts
authors.affiliation: Cognitive and Behavioral Neuroscience Program, Department of Psychology, George Mason University, United States; Interdepartmental Program in Neuroscience, George Mason University, United States. Electronic address: cmcdona3@gmu.edu.
authors.forename: Craig G
authors.initials: CG
authors.lastname: McDonald
authors.affiliation: Cognitive and Behavioral Neuroscience Program, Department of Psychology, George Mason University, United States; Human Factors and Applied Cognition Program, Department of Psychology, George Mason University, United States; Interdepartmental Program in Neuroscience, George Mason University, United States.
authors.forename: Matthew S
authors.initials: MS
authors.lastname: Peterson
mesh_terms: D000293:Adolescent; D000328:Adult; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D010364:Pattern Recognition, Visual / Q000502:physiology*; D065852:Spatial Memory / Q000502:physiology*; D055815:Young Adult
keywords: CDA; ERP; Encoding; Spatial; Working memory