title: Improvement in visual search with practice: mapping learning-related changes in neurocognitive stages of processing.
abstract: Practice can improve performance on visual search tasks; the neural mechanisms underlying such improvements, however, are not clear. Response time typically shortens with practice, but which components of the stimulus-response processing chain facilitate this behavioral change? Improved search performance could result from enhancements in various cognitive processing stages, including (1) sensory processing, (2) attentional allocation, (3) target discrimination, (4) motor-response preparation, and/or (5) response execution. We measured event-related potentials (ERPs) as human participants completed a five-day visual-search protocol in which they reported the orientation of a color popout target within an array of ellipses. We assessed changes in behavioral performance and in ERP components associated with various stages of processing. After practice, response time decreased in all participants (while accuracy remained consistent), and electrophysiological measures revealed modulation of several ERP components. First, amplitudes of the early sensory-evoked N1 component at 150 ms increased bilaterally, indicating enhanced visual sensory processing of the array. Second, the negative-polarity posterior-contralateral component (N2pc, 170-250 ms) was earlier and larger, demonstrating enhanced attentional orienting. Third, the amplitude of the sustained posterior contralateral negativity component (SPCN, 300-400 ms) decreased, indicating facilitated target discrimination. Finally, faster motor-response preparation and execution were observed after practice, as indicated by latency changes in both the stimulus-locked and response-locked lateralized readiness potentials (LRPs). These electrophysiological results delineate the functional plasticity in key mechanisms underlying visual search with high temporal resolution and illustrate how practice influences various cognitive and neural processing stages leading to enhanced behavioral performance.
authors.affiliation: Center for Cognitive Neuroscience and School of Psychology, Cardiff University, Cardiff CF10 3AT, United Kingdom.
authors.forename: Kait
authors.initials: K
authors.lastname: Clark
authors.affiliation: Center for Cognitive Neuroscience and Department of Psychiatry, Duke University Medical Center, Durham, North Carolina 27708, and.
authors.forename: L Gregory
authors.initials: LG
authors.lastname: Appelbaum
authors.affiliation: Center for Cognitive Neuroscience and BCN Neuroimaging Center, University of Groningen, 9700 AB Groningen, The Netherlands.
authors.forename: Berry
authors.initials: B
authors.lastname: van den Berg
authors.affiliation: Center for Cognitive Neuroscience and Department of Psychology and Neuroscience, Duke University, Durham, North Carolina 27708.
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Mitroff
authors.affiliation: Center for Cognitive Neuroscience and Department of Psychology and Neuroscience, Duke University, Durham, North Carolina 27708, Department of Psychiatry, Duke University Medical Center, Durham, North Carolina 27708, and woldorff@duke.edu.
authors.forename: Marty G
authors.initials: MG
authors.lastname: Woldorff
mesh_terms: D000293:Adolescent; D000328:Adult; D001288:Attention / Q000502:physiology; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D058256:Brain Waves / Q000502:physiology; D004192:Discrimination, Psychological / Q000502:physiology; D004569:Electroencephalography; D005071:Evoked Potentials; D005260:Female; D006801:Humans; D007858:Learning / Q000502:physiology*; D008297:Male; D011597:Psychomotor Performance; D011930:Reaction Time; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult
keywords: EEG; LRP; N2pc; attention; learning; visual search
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