Event files (fidl) are not BIDS compatible

[andrazmatkovic]

Currently, event files have the extension .fidl and look like this:

2.0 cue stimulus response
6.0  0 1 315
10.0 1 3 315

Here, the first line contains metadata: the first number refers to TR, the other three words are the names of the events that are encoded in second column. The columns after the first line refer to the onset of the event, event code, event duration. Additional columns are behavioral coregressors.

The structure of this file is confusing to new users, therefore I recommend adhering to BIDS event file structure. This will also allow easy import from BIDS.

In BIDS, event file is a .tsv file with the following columns:

onset   duration    trial_type  response_time   stim_file   channel annots
1.23    0.65    start   1.435   images/red_square.jpg   n/a n/a
5.65    0.65    stop    1.739   images/blue_square.jpg  n/a n/a
12.1    2.35    n/a n/a n/a F,1|F,2|Cz  musc

Only the first two columns are strictly required, others are optional. The structure is quite similar to fidl, the main differences are:

• columns are named
• different order of columns
• TR is not specified

What need to be changed: to be discussed.