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J. Palix, I. Viaud-Delmon, C. Michel, U. Leonards; Cortical dynamics of attention during visual search: An event-related potential study. Journal of Vision 2001;1(3):112. doi: https://doi.org/10.1167/1.3.112.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To investigate the temporal dynamics of attention in visual search, we compared electrocortical activation patterns for feature and conjunction search with low and high attentional demands, respectively. Methods: Continuous EEG (125 channels) of sixteen volunteers was recorded, while subjects performed feature search (line orientation) and conjunction search (line orientation & contrast polarity). Event-related potentials were compared for the two search types, using a time-segmentation procedure based on map topography, and a waveform analysis. Results: For both search types, segmentation analysis revealed 9 successive topographic maps (between 200 ms prior and 600 ms after stimulus onset). Maps 3 to 5, 120 to 300 ms after stimulus onset, showed significant topographic differences between feature and conjunction search. Waveform analysis indicated that the N2pc component, previously suggested as electrophysiological indicator for spatial attention shifts distinguishing between feature and conjunctions search, was restricted to the time window of map 5 (250–300 ms). Conclusions: Our results revealed that cortical temporal dynamics differ between little attention demanding feature and attentive conjunction search 100 ms earlier to those commonly attributed to spatial shifts of attention. This suggests that spatial attention shifts as indicated by the N2pc component are not sufficient to explain attention mechanisms in visual search.
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