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Exp Brain Res (2008) 185:709717 DOI 10.1007/s00221-007-1196-5
RESEARCH ARTICLE
Attention for perception and action: task interference for action planning, but not for online control
Geniva Liu Romeo Chua James T. Enns
Received: 12 July 2007 / Accepted: 23 October 2007 / Published online: 15 November 2007 Springer-Verlag 2007
Abstract Human vision allows us both to perceive our surroundings (e.g., identify a cup) and to interact with them (e.g., reach for a cup). It is generally accepted that these functions are supported by a ventral system for conscious object identication and a dorsal system for unconscious control of action, but little research has addressed the extent to which these two systems can operate concurrently. We show that the identication of one object interferes with the planning of a pointing action to a second object, but does not interfere with the visually guided control required to complete the action. This lack of interference holds even for actions that must be modied in response to a dynamically changing scene. These ndings support the proposal that the planning of action shares resources with conscious tasks of perception, but that the online control of already-initiated actions does not.
Keywords Attention Visual perception
Psychomotor performance
Introduction
A large body of research supports the idea that human vision consists of at least two different cortical systems: a ventral stream for conscious perception of objects (e.g., identication, categorization) and a dorsal stream for unconscious, online control of visually guided action toward objects (e.g., pointing, grasping; Milner and Goo-dale 1995; but see also Franz et al. 2000; Glover 2004). Here, we use this dual systems theory as a novel framework for examining dual-task performance by studying how the ventral and dorsal systems interact when they are required simultaneously.
A typical way to study the human ability to share mental resources among tasks is the dual-task paradigm, in which participants are asked to perform two tasks at once or in close succession to one another. A comparison of performance under dual- and single-task conditions is used to index the efciency with which participants are able to perform tasks concurrently. Extensive research of this kind indicates that it is generally difcult to perform two visual tasks concurrently, with performance decits exhibited in the task that is...