[Eeglablist] Marking and Extracting continous portions of data after epoching

Li, Lucia M lucia.li at imperial.ac.uk
Wed Feb 11 07:39:57 PST 2015

Dear eeglab users & experts,

Would someone be able to help me out with a query?

I am analysing EEG data from a task. This task is separated into 3 blocks (beginning, middle and last), and there are several trials within each block. I would like to compare EEG parameters between the trials occurring in different blocks. I know that I can highlight continuous portions of data for rejection (e.g. reject the middle and last portions, and be left with just the beginning portion). However, I don't want to do this because I think that subsequent cleaning on the divided data may introduce bias - i.e. differences between the blocks may be because of differences in cleaning and not due to differences in neurological state.

I have tried a couple of different methods (e.g. adding markers in, but eeglab doesn't seem to allow bins of different sizes to exist; trying to use Edit --> select data using events, but after cleaning and deleting noisy epochs the markers may be deleted). The stimulus markers do not differentiate between each block.

Another potential way is to re-lable the event markers such that the ones in each block are different - does anyone know of a way I can selectively re-label event markers? (i.e. turn all the event markers '4' from the first block only to '44')?

Does anyone have any other suggestions for how I can mark divide my data (after epoching and cleaning) into the blocks?

Thank you in advance for your help.

Kind regards,
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