Abstract
Hidden formatting deleted. Delete this text! none;text-autospace:none">[Purpose] We previously compared two types of EEG components, steady-state visual evoked potential (SSVEP) and P300 of event-related potential (ERP), and found that the two measures showed different spatial characteristics: SSVEP showed broad spatial tuning while P 300 showed narrower one. It might be the case that different stages of visual processing have different spatial aspects of visual attention. To investigate the stage differences of visual attention, we compared the spatial spreads of visual attention with different tasks assigned as dual tasks: letter identification and luminance change detection. Hidden formatting deleted. Delete this text! none;text-autospace:none">[Method] The observer attended to one of eight circularly arranged disks to detect targets as the primary task in the rapid serial visual presentation sequence, ignoring stimulus at other locations. The secondary task was to detect luminance decrement at either of eight disks during 6s of stimulus presentation. We recorded manual responses for the two tasks and EEG signals to analyze ERP and SSVEP components: ERP for target presentations for both tasks and SSVEP for eight disks that have luminance flicker with different temporal frequencies. We obtained spatial tunings of attention modulation by change in performance or EEG amplitude (SSVEP or P300) as a function of distance from the focus of attention along the circular path. Spatial spread of visual attention was estimated for each of the four measures separately. Hidden formatting deleted. Delete this text! none;text-autospace:none">[Results] Spatial spread was broader for SSVEP than for P300 and was broader for luminance detection than for letter identification. They suggest that spatial characteristics of visual attention differ for different stages of visual processing. Visual attention may spread more broadly at early visual stages than at later stages.
Meeting abstract presented at VSS 2014