[FieldTrip] ft_databrowser & ft_rejectartifact - wrong number of trials rejected

[Schoffelen, J.M. (Jan Mathijs)]

Hi Christine,

Are you sure that the tmpdata_small and data_segm_offsetcorr are consistent with respect to each other? As long as this is not the case, I am not surprised that fieldtrip ‘misbehaves’.

Best,
Jan-Mathijs



On 08 May 2016, at 09:26, Blume Christine <christine.blume at sbg.ac.at<mailto:christine.blume at sbg.ac.at>> wrote:

Good morning,

I discovered that using ft_databrowser & ft_rejectartifact to preprocess my EEG data, often the wrong number of trials is rejected. This is the code I am using and it inherits data resulting from ft_redefinetrial.

    cfg = [];
    cfg.latency = [-2 2]; % period of interest
    tmpdata_small = ft_selectdata(cfg,data_segm_offsetcorr);

    cfg = [];
    cfg.layout = layout2;
    cfg.showlabel = 'yes';
    cfg.channel = 'EEG';
    cfg.gradscale = 0.04;
    cfg.continuous = 'no';
    % filtering only for artifact rejection
    cfg.preproc.lpfilter  = 'yes';
    cfg.preproc.lpfreq = 40;

    cfg_databrowser = ft_databrowser(cfg, tmpdata_small);
    data_segm_offsetcorr = ft_rejectartifact(cfg_databrowser, data_segm_offsetcorr);

If I now, for example mark 10 trials in the databrowser and then run ft_rejectartifact, it tells me:

detected 10 visual artifacts
rejected 8 artifacts completely

Something seems to be wrong here as I clearly marked 10 artifacts (don't really care whether they are visual or not), but only 8 are removed. The problem gets worse when I call the function a second time, which is when usually none of the marked artefacts are rejected at all.

Any idea where the problem could be?

Many thanks!
Best,
Christine
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