[visionegg] Ghosting of previous stimulus (was: Advice on using Presentation for sequential stimulus.)
- From: Simeon Fitch <metasim@xxxxxxxxx>
- To: visionegg@xxxxxxxxxxxxx
- Date: Wed, 24 Aug 2005 12:11:37 -0400
Andrew,
I definitely want to follow up later with some ideas on how to add
simplified support for sequential stimuli, as you've described below
(I've a pressing deadline right now). My current approach (as I
previously described) has run into a problem when in full screen mode
I'm hoping is related to my neglecting a setting or something, but I'm
not quite sure how to start tracking it down.
In my experiment, I first show the Vision Egg provided FixationSpot,
then display three different "frames" of a dot lattice mask (@50ms
each), and then the main stimulus. In between each of the three mask
frames, the FixationSpot re-appears on the screen! It's almost as if
the FixationSpot is being redrawn, or it exists in a back buffer
that's not getting cleared, or something similar.
This problem does *not* happen when in windowed mode, so it could just
be a OpenGL driver bug (OpenGL 1.3 ATI-1.4.6, ATI Radeon 9200 OpenGL
Engine)
Any tips on how to debug this would be appreciated.
Regards,
Simeon
On 8/22/05, Andrew Straw <astraw@xxxxxxxxxxx> wrote:
<snip>
>
> This is an area where improvements could be made, I think. I'm somewhat
> inspired by the "trial strings" of PsyScript/RSVP [1]. Although I've
> never worked with it, it seems to describe the time-course of entire
> experiments in strings of a few characters. So, some kind of simplified
> experiment description is an interesting possibility. I assume such
> simplification would come at the expense of assumptions about what
> experiments people want to do, but perhaps those assumptions are met
> enough of the time to justify implementing some system like this.
>
> [1]: A description of the "do trial" command in PsyScript:
> http://www.maccs.mq.edu.au/~tim/psyscript/docs/trials/intro_to_do_trial.html
>
> Simeon Fitch wrote:
<snip>
> > # Main experimentation loop
> > for trial in conditions:
> > lattice.setTrial(trial)
> >
> > fixationPres.go()
> > maskPres.go()
> > latticePres.go()
> > responsePres.go()
> >
> > dataFileWriter.writerow(trial.values())
--
Simeon H.K. Fitch, Owner
Mustard Seed Software
http://www.mseedsoft.com/
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