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How to extract eye tracking data by trial ID

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Hi there,
I have lots of eye tracking data from a 2 alternate forced choice experiment. In total, 496 trials per participant.
The data are in .asc format, and include MSGs for every forced choice onset. For example:
I would like to extract the data for each 2AFC trial. Such that my ideal data set would include only saccades/fixations/blinks within the 2AFC period, per trial (Trial ID 1 2AFC : Trial ID 496 2AFC).
Whilst i've been able to extract saccade/fixation/etc information using a toolbox, I'm stuck on how to filter the data by trial.
Maybe this can't even be achieved! But would appreciate any insights.

Risposta accettata

dpb
dpb il 14 Feb 2023
Modificato: dpb il 15 Feb 2023
Easiest would be to read the file line-by-line, looking for the magic value and then save data until the next, adding the trial as a variable...
You forgot to attach any usable data for anybody to actually demonstrate, but "air code" would look something like --
fid=fopen('YourFile.Dat');
ID=input('Enter the magic ID to look for, please; ','s')
ID=upper(ID);
pat="MSG"+wildcardPattern+digitsPattern(7)+wildcardPattern+"TRIALID"+wildcardPattern+digitsPattern(1,4)+wildcardPattern+upper(ID);
j=0; % the counter
d=[]; % empty accumulator for data
l=fgetl(fid);
while ~feof(fid)
if matches(l,pat)
j=j+1; % increment counter
l=fgetl(fid); % get first data line in section
end
try
d=[d;[j str2double(l)]]; % convert line to data; add trial number and array
l=fgetl(fid); % record for next loop
catch % presume failure means next section
% do nothing special, pass on to next test if in wanted section
l=fgetl(fid); % record for next loop
end
end
fid=fclose(fid);
will (hopefully) leave you with the array of values with the trial # as first variable; save as a matrix or convert to a table as desired.
  1 Commento
jlouise2022
jlouise2022 il 15 Feb 2023
Hi,
Thanks for your insight. Accepted as answer as this may help someone else.
I'm now working with .edf files as they are easier to convert into mat files.

Accedi per commentare.

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