Stimuli/ Triggers/ Timing difficulties

[Douglas]

Hi again

Thanks a lot for your prompt reply
We just did what you said, a new problem occurred!

Th first time after running the experiment,  a new unknown trigger
showed up as "50"! and the second time there were no triggers shown on
IWave ar all!

Do you have any ideas, why this is happening?


On Apr 19, 2:17 pm, David McFarlane <mcfar... at msu.edu> wrote:
> Sorry, I forgot to elaborate on the "finesse" part.  The shortcoming
> of this solution is that you *must* remember to adjust the PreRelease
> value any time that you change Duration, and it is *very* easy for
> most users to overlook that, as I can tell you from experience!
>
> -- David McFarlane
>
> At 4/19/2012 02:09 PM Thursday, you wrote:
>
>
>
>
>
>
>
> >We do this all the time for our EEG programs, but it requires a
> >little finesse.  In short, we use a PreRelease value of 1-20 ms less
> >than the Duration of the stimulus object.  E.g., for your object
> >with a Duration of 500, set PreRelease to 490.  Now your trigger
> >will coincide exactly with the onset of your stimulus, and will last
> >for 10 ms, when the "offset" of the stimulus occurs.
>
> >Note that, in E-Prime parlance, stimulus "offset" does not mean
> >either the end of stimulus presentation, nor the onset of the
> >following stimulus; "offset" actually refers to when E-Prime stops
> >executing code for that object and moves on to executing further
> >instructions.  Someday I need to write this all up, but it's tricky
> >to describe this all correctly.
>
> >-----
> >David McFarlane
> >E-Prime training
> >online:  http://psychology.msu.edu/Workshops_Courses/eprime.aspx
> >Twitter:  @EPrimeMaster (twitter.com/EPrimeMaster)
>
> >At 4/19/2012 01:44 PM Thursday, you wrote:
> >>Hello E-Prime experts,
>
> >>We are Working in our lab with Iwave and E-prime;
>
> >>There's a problem that bothers us.
>
> >>The triggers stay for 500 msec, exactly the same duration as the
> >>Stimuli. We want to write a code that makes the trigger and stimulus
> >>onset at the same time exactly( which is the case now with the new
> >>line: Stimulus.OnsetSignalData = c.getattrib(`"Cond") ) AND the
> >>trigger to offset as quickly as possible while the stimulus stays on
> >>the screen for 500 msec.
>
> >>Looking forward to any solutions
>
> >>Many thanks in advance.

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