[Eeglablist] Problem epoching backwards using 0 as start/end point

[Dritan Nikolla]

Hi Makoto,
There is a 5 to 7 seconds (random) interstimulus interval, or SOA as you term it. I am thinking that the error I am getting is not actually an error but an artefact of the viewing platform. An epoched set, when displayed on screen with 0 to -4 time segment, it is possible that the event at time 0 is not displayed on screen with right epoch (which should be at the far end, the right side of the screen) but it displays as left with the following epoch. I think this is causing the confusion.
Best,Dritan 

    On Friday, 27 July 2018, 23:45:55 BST, Makoto Miyakoshi <mmiyakoshi at ucsd.edu> wrote:  
 
 Dear Dritan,
> I found that both codes above epoch from event to 4 second after the event and I want to epoch 4 seconds before.

What is your SOA (stimulus onset asynchrony, which is the interval from stimulus offset to the next stimulus onset)?
Makoto
On Thu, Jul 19, 2018 at 3:35 AM Dritan Nikolla <dritannikolla at yahoo.com> wrote:

Hi all,
I am trying to epoch from 4 seconds before an event up to the event. the code I am using is this:

EEG = pop_epoch( EEG, triggers, [0  -4], 'newname', sprintf('epoch_%s', files(index).name), 'epochinfo', 'yes');




I also tried this:




EEG = pop_epoch( EEG, triggers, [-4  0], 'newname', sprintf('epoch_%s', files(index).name), 'epochinfo', 'yes');



triggers is a cell array: 




  triggers = {'Center_Right_Right' 'Center_Right_Left' 'Center_Left_Right' 'Center_Left_Left'...

              'L_Right_Right' 'L_Right_Left' 'R_Right_Right' 'R_Right_Left' 'L_Left_Right'...

              'L_Left_Left' 'R_Left_Right' 'R_Left_Left' 'CenterEmpty_Right'       'CenterEmpty_Left'...

              'RightEmpty_Right' 'RightEmpty_Left' 'Left_Empty_Right' 'Left_Empty_Left'};
The algorithm works fine, no errors, however, when I checked the data manually I found that both codes above epoch from event to 4 second after the event and I want to epoch 4 seconds before. What am I doing wrong?
Thank you very much,Dritan_______________________________________________
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-- 
Makoto Miyakoshi
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
  
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