timing error

[Tobi]

Thanks a lot,

when I don't use OffsetSync, I have an error of only 10 ms (and not 20
ms).
But with the skipping ISI-slide when ISI is 0, that works fine. No
timing errors then.
Script runs fast I can tell ;)

Cheers,
Tobias

On 14 Jan., 22:55, David McFarlane <mcfar... at msu.edu> wrote:
> Tobias,
>
> I just noticed in your post that started this thread you said that
> you use vertical blank for both Onset Sync and Offset Sync.  In
> general, for visual display objects I would set Onset Sync to
> vertical blank, and Offset sync to (none), which is the default (I
> leave it as an exercise for you to ponder why this makes sense).  But
> if you instead used a Wait object for your ISI then, as Mich
> mentioned, I might set both Onset Sync and Offset Sync to (none) and
> then duration should work as expected.  Even then I would rather
> follow Mich's further advice to either use a bit of inline script to
> skip past the ISI, or use a separate Procedure without the ISI,
> whenever the ISI duration is 0.  You might be surprised at how much
> script will run in less than a millisecond.  As you read in Chapter
> 3, the real time bottlenecks are disk access (e.g., loading image and
> sound files), display synchronization, and interruptions from the
> operating system.  But don't take my word for this.  You can time
> script yourself using the microsecond clock in E-Prime (see the Clock
> topic in the online E-Basic Help).
>
> -- David McFarlane, Professional Faultfinder
>
> At 1/14/2010 07:51 AM Thursday, you wrote:
>
> >Okay, after having read the entire Chapter 3 I found out that I have
> >actually done everything right in terms of setting. However I found
> >the reason for the timing error having a closer look at the result
> >file. The timing error was always there in case the slide "ISI"
> >between the slides "Cue" and "Target" had the duration variable 0. I
> >also used other durations for "ISI", specified in the block list. As a
> >slide always uses at least on circle, the timing error then occurs
> >even when using OnsetSync function.
>
> >This seems to be a serious problem. Do you have any idea how to solve
> >this problem? I could maybe use a script asking for the ISI duration
> >value and skipping the "ISI" slide when duration is 0. However a
> >script in a short sequence of stimuli might also cause some timing
> >problems. Maybe you have a better idea?
>
> >BEst,
> >Tobias
>
> >On 14 Jan., 01:33, Tobi <tobias... at gmail.com> wrote:
> > > Thanks David,
>
> > > I just found the User's Guide. I will read the 50 pages of chapter 3,
> > > I promise.
> > > Could you or anyone give me a hint for my special problem anyway?
>
> > > Thanks a lot,
> > > Tobias
>
> > > On 13 Jan., 14:45, David McFarlane <mcfar... at msu.edu> wrote:
>
> > > > Tobias,
>
> > > > Everything you need to know about critical timing is in Chapter 3 of the
> > > > User's Guide that came with E-Prime.  Go study that now.  Do not pass
> > > > Go, do not collect $200.
>
> > > > -- David McFarlane, Professional Faultfinder
>
> > > > > Hi everyone,
>
> > > > > I am apparently having a timing error. In a procedure I use a slide
> > > > > called "target". I display it for 78 ms on a screen with 100 Hz which
> > > > > should result in display times of 80 ms. In the result file I find
> > > > > "target.OnsetDelay" values of either 2 ms (as wished) or 20 ms.
> > > > > "target.DurationError" is 33 ms.
>
> > > > > I used "vertical blank" for "OffsetSync" and "OnsetSync" and 100 ms of
> > > > > pre-release time to virtually avoid such errors.
>
> > > > > Another slide beeing displayed before the target (98 ms, same
> > > > > settings) does not show this error.
>
> > > > > Does anyone have an idea what this error could result from?
>
> > > > > Thanks a lot,
> > > > > Tobias
>
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