ERP Averaging

Visual Hemifield Stimulation

EEG/ERP sweeps of right parietal surface potentials (gif file 240 kB)

EEG activity [µV] of one healthy individual, recorded over the right parietal region (electrode site P8) with a nose tip reference (positivity is plotted downwards). The task was to attend to brief presentations of visual stimuli to either the left or right hemifield (visual half-field paradigm). Shown are data of 64 consecutive trials, time-locked to stimulus onset (sweeps of 1,280 ms length, including a 200 ms pre-stimulus baseline). The brown lines represent the raw EEG activity recorded for each event, the blue lines are the running ERP averages, which include all previous events. EEG sweeps were low pass filtered at 20 Hz (24 dB/Oct). At this recording location for this individual, the ERP component structure consists of P1 (peak latency approximately 130 ms), N2 (220 ms), two P3 peaks (380 and 500 ms), and a negative slow wave (900 ms). Note that unsystematic EEG activity (e.g., during the pre-stimulus baseline period) averages to zero with a suffcient number of recorded sweeps. © Kayser 11/29/2001

EEG/ERP sweeps of vertex surface potentials (gif file 322 kB) To view similar running averages for auditory stimuli, click here.


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