title: The flexible focus: whether spatial attention is unitary or divided depends on observer goals.
abstract: The distribution of visual attention has been the topic of much investigation, and various theories have posited that attention is allocated either as a single unitary focus or as multiple independent foci. In the present experiment, we demonstrate that attention can be flexibly deployed as either a unitary or a divided focus in the same experimental task, depending on the observer's goals. To assess the distribution of attention, we used a dual-stream Attentional Blink (AB) paradigm and 2 target pairs. One component of the AB, Lag-1 sparing, occurs only if the second target pair appears within the focus of attention. By varying whether the first-target-pair could be expected in a predictable location (always in-stream) or not (unpredictably in-stream or between-streams), observers were encouraged to deploy a divided or a unitary focus, respectively. When the second-target-pair appeared between the streams, Lag-1 sparing occurred for the Unpredictable group (consistent with a unitary focus) but not for the Predictable group (consistent with a divided focus). Thus, diametrically different outcomes occurred for physically identical displays, depending on the expectations of the observer about where spatial attention would be required.
authors.affiliation: School of Psychology and Exercise Science, Murdoch University.
authors.forename: Lisa N
authors.initials: LN
authors.lastname: Jefferies
authors.affiliation: Department of Psychology, The University of British Columbia.
authors.forename: James T
authors.initials: JT
authors.lastname: Enns
authors.affiliation: Department of Psychology, Simon Fraser University.
authors.forename: Vincent
authors.initials: V
authors.lastname: Di Lollo
mesh_terms: D000328:Adult; D059031:Anticipation, Psychological / Q000502:physiology; D001288:Attention / Q000502:physiology*; D054518:Attentional Blink / Q000502:physiology; D005260:Female; D006040:Goals; D006801:Humans; D008297:Male; D011897:Random Allocation; D013028:Space Perception / Q000502:physiology*; D055815:Young Adult