title: A right hemisphere advantage at early cortical stages of processing alphanumeric stimuli. Evidence from electrophysiology.
abstract: This study investigates hemispheric asymmetry evoked by non-target alphanumeric stimuli in a bilateral rapid serial visual presentation (RSVP) task. Our indicators of asymmetry are shorter latencies and larger amplitudes of the right hemisphere (RH) P1 and N1 components of visual evoked potentials (VEPs). This VEP asymmetry might reflect either a RH advantage, possibly in early perceptual processing, or for familiar stimuli, or for directing attention, or might be a paradoxical reflection of left hemisphere specialization in letter processing. Experiment 1 showed that the VEP asymmetry decreased, though remained present, with unfamiliar stimuli (Tibetan letters), as compared to familiar stimuli (Latin letters and Arabic digits). Experiment 2 showed that while leftward and rightward attentional biases affected the relation between hemispheres contra- and ipsilateral to attended visual fields, the VEP asymmetry remained independent of attention. As the most parsimonious explanation, the primary cause of the VEP asymmetry seems to be a general predominance of the RH in early perceptual processing.
authors.affiliation: Institute of Psychology, Jagiellonian University in Kraków, Poland; Department of Neurology, University of Lübeck, Germany. Electronic address: d.asanowicz@uj.edu.pl.
authors.forename: Dariusz
authors.initials: D
authors.lastname: Asanowicz
authors.affiliation: Department of Neurology, University of Lübeck, Germany; Institute of Psychology II, University of Lübeck, Germany.
authors.forename: Rolf
authors.initials: R
authors.lastname: Verleger
authors.affiliation: Department of Neurology, University of Lübeck, Germany.
authors.forename: Lena
authors.initials: L
authors.lastname: Kruse
authors.affiliation: Department of Neurology, University of Lübeck, Germany.
authors.forename: Kathrin
authors.initials: K
authors.lastname: Beier
authors.affiliation: Department of Neurology, University of Lübeck, Germany.
authors.forename: Kamila
authors.initials: K
authors.lastname: Śmigasiewicz
mesh_terms: D000328:Adult; D001288:Attention / Q000502:physiology; D004569:Electroencephalography; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008297:Male; D010775:Photic Stimulation; D014794:Visual Fields / Q000502:physiology*; D055815:Young Adult
keywords: Attentional bias; Hemispheric asymmetry; Perceptibility hypothesis; RSVP; Right hemisphere advantage; Visual evoked potentials