COGNITIVE NEUROSCIENCE AND NEUROPSYCHOLOGYAsymmetry of P3 amplitude during oddball tasks reflects the unnaturalness of visual stimuliMinami, Tetsutoa; Goto, Kimikob; Kitazaki, Michiteruc; Nakauchi, ShigekibAuthor Information aIntelligent Sensing System Research Center bDepartment of Information and Computer Sciences cResearch Center for Future Vehicle, Toyohashi University of Technology, Toyohashi, Aichi, Japan Correspondence to Dr Tetsuto Minami, PhD, Intelligent Sensing System Research Center, Toyohashi University of Technology, 1-1, Hibarigaoka Tempaku, Toyohashi, Aichi 441-8580, Japan Tel: +81 532 44 6765; fax: +81 532 44 6651; e-mail: [email protected] Received 17 June 2009 accepted 19 August 2009 NeuroReport: October 28, 2009 - Volume 20 - Issue 16 - p 1471-1476 doi: 10.1097/WNR.0b013e3283321cfb Buy Metrics Abstract This study examined the relationship between the ‘naturalness’ of a visual stimulus and the event-related potentials measured during an oddball task. The study focused on asymmetry of the P3 amplitude during an oddball task or P3 asymmetry. Participants performed two visual oddball tasks using a pair of stimuli (A and B): one in which A was the target stimulus and B was the standard stimulus and vice versa. The stimuli consisted of natural–unnatural pairs of visual stimuli (e.g. upright–inverted faces, possible–impossible human poses). As a result of comparing the amplitudes of the target stimuli, P3 asymmetry was found in natural–unnatural pairs; that is, their naturalness differentiated the target P3 amplitude: larger P3 to the unnatural target than to the natural one. This study showed that P3 asymmetry reflected unnaturalness and unfamiliarity of visual stimuli. © 2009 Lippincott Williams & Wilkins, Inc.