Therefore I've recorded test data with blinks every 5 seconds. The blinks can be seen clearly in the EEG data. The data have been recorded with 128Hz, bandpass filtered (1-30Hz) and resampled (64Hz).
After running the ICA ('fastica') the blinks clearly show up in 3 source signals (IC #0, #1 and #2). I have the same behavior for different amounts of ICs.
I think the blinks are to strong and that's why they spread in more than one source signal.
I wonder if there is a way to let the blinks only show up in 1 source signal?