The Attention Network Test (ANT) is a brief computerized battery measuring three independent behavioral components of attention: Conflict resolution (ability to overcome distracting stimuli), spatial Orienting (the benefit of valid spatial pre-cues), and Alerting (the benefit of temporal precues). Imaging, clinical, and behavioral evidence demonstrate hemispheric asymmetries in these attentional networks. We constructed a lateralized version of the ANT (LANT), with brief targets flashed in one or the other visual hemifield. We also modified the tests by including invalid spatial cues in order to measure the cost component of Orienting. In a series of experiments, we investigated the efficiency of the attention networks separately in each hemisphere. Participants exhibited significant estimates of all networks measured by the LANT, comparable to the ANT. The three networks were represented in each hemisphere separately and were largely comparable across the two hemispheres. We suggest that the LANT is an informative extension of the original ANT, allowing for measurement of the three attention networks in each hemisphere separately. Keywords attention; conflict; executive; orienting; vigilance; hemispheric specialization; hemispheric independence Attention is believed to involve a bilaterally distributed network whose components are asymmetrically represented in the two hemispheres. Physiological/imaging correlates of attention show that sustained attention (vigilance) tasks yield prefrontal and parietal activation, preferentially in the right hemisphere (RH) (Posner & Petersen, 1990). Stroop and flanker-type conflict resolution tasks selectively engage the anterior cingulate cortex and Address correspondence to Deanna J. Greene, Department of Psychology, University of California, Los Angeles, 1285 Franz Hall, Los Angeles, CA 90095-1563, USA, Email: HYPERLINK "mail to: djgreene@ucla.edu" djgreene@ucla.edu, Phone: (310) Fax: (310) 206-3655. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. (Fan, Flombaum, McCandliss, Thomas, & Posner, 2003). Orienting of visuospatial attention selectively engages right parietal cortex (Corbetta, Kincade, Ollinger, McAvoy, & Shulman, 2000). Clinical and behavioral evidence is largely consistent with the imaging data. Clinical studies confirm that the RH is specialized for alerting, arousal and vigilance (Posner & Petersen, 1990). Hemi-neglect is more often reported and more severe in patients with right than left parietal lesions (for a review, see Mesulam, 1999). Further, normal and split-brain participants demonstrate a gradient ...
