Attention spreads measured by steady state visual evoked potential and by event related potential S Shioiri1, H Honjo2, Y Kashiwase2, R Tokunaga1, K Matsumiya1, I Kuriki1 |
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1Research Institute of Electrical Communicatio, Tohoku University, Japan |
| We investigated spatial spreads of visual attention, measuring EEG components called SSVEP (Steady-State Visual Evoked Potential) and ERP (event related potential). SSVEPs are sinusoidally-evoked potentials induced by constantly flickering stimuli, having the same frequency as stimulus frequency and ERP is the potential evoked by stimulus presentation. Since both components are modulated by attention, spatial spread of visual attention can be estimated by measuring them at different locations. There were eight stimuli arranged circularly at a fixed distance from the fixation point. A cue was presented at one of the eight locations and an RSVP (rapid serial visual presentation) task was given at the location. We found that clear peaks in SSVEP signals at frequencies corresponding to stimulus flickers and that the amplitude was modulated by attention. We also found that the p300 component of ERP to the RSVP target was modulated by attention. The attention modulation of ERP showed gradual decrease with the distance from the cued location whereas p300 showed clear attentional modulation only at the cued location. The difference can be interpreted by assuming that SSVEP and p300 reflect characteristics of different levels of the attention system. |
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