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

[Makoto Miyakoshi]

Dear Dritan,

Hmm your explanation makes sense. I was thinking the similar possibility,
that is, if your SOA is exact 4 sec, then [-4 0] and [0 4] should actually
show the same plot...
Anyways, if you figured it out that's great.

Makoto

On Fri, Jul 27, 2018 at 6:04 PM Dritan Nikolla <dritannikolla at yahoo.com>
wrote:

> 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
>


-- 
Makoto Miyakoshi
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
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