Concentric Circles

1
Hi all,

I am fairly new to psychtoolbox but have some konwledge oding in matlab.

For one of our experiments we are trying to code a stimuli whose display should consist of  Concentric Rings which expand and  then contract.

I also want to implement an attention task in to this where subject have has to repsonse when the fixation cross changes its color.

Do anybody have any ideas or have done somehting similar to the above explanined method. I especially would like to get some ideas for the expanding and contracting concentric circles part?

Any help is greatly appreciated.

Thanks a lot in advancne,

Bala

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2
Which operating system and what kind of graphics
card do you have? There are elegant solutions, but
they require hardware with fragment shader support.

-mario

--- In psychtoolbox@yahoogroups.com, tudor badea <tudorcb@...> wrote:
>
> Keith,
>
> the major difference that is important to me is that
> the edge of the circles moves at a constant, smooth
> speed, because we are testing eyetracking, so we want
> a moving edge that expands. We then project that on
> the inside of a cylinder, which creates basically a
> pattern of stripes sliding up and down, to test
> tracking in the vertical direction.
>
> Even if you reveal the mask smoothly, the edges won't
> move if i understand your program correctly. Anyhow,
> this is not a very fancy application.
>
> Thanks for your input and help though. I need all the
> help i can get.
>
> Tudor
> --- Keith Schneider <ks@...> wrote:
>
> > Well the way it works is that it generates a single
> > image, and then
> > uses masking to reveal only part of the image at a
> > time. You can
> > mask any number of annuli. Depending on how you
> > want your rings to
> > look, this may work for you.
> >
> > keith
> >
> > On May 13, 2007, at 9:41 PM, tudorcb wrote:
> >
> > > Hi Keith,
> > >
> > > thanks for your help. Your program is very
> > complex indeed and was
> > > really helpful for me
> > > to understand what to, and i wrote a very simple
> > one that seems to
> > > be doing the right
> > > thing.
> > > Basically i am trying to get a "bull's eye
> > target" with
> > > alternating black white, and it does
> > > so for smaller initial diameters. As soon as it
> > passes a certain
> > > size, it slows down visibly.
> > > My guess is that it spends too much time
> > calculating an dthen
> > > drawing all the n
> > > innercircles it has to make. Is there a way to
> > store the output
> > > and then play it back ? I am
> > > figuring that once it has been generated, it
> > should be displayed at
> > > the same speed (that i
> > > can hopefully control) for all frames.
> > >
> > > In any respect, thanks a lot for your help.
> > >
> > > Tudor
> > >
> > >
> > >
> > >
> > > --- In psychtoolbox@yahoogroups.com, Keith
> > Schneider <ks@> wrote:
> > >>
> > >> Hi Bala,
> > >>
> > >> Here's an expanding (or contracting) ring
> > stimulus I use for fMRI
> > >> retinotopy. If you're new to the psychtoolbox it
> > may be difficult to
> > >> go through the code, but here it is. Perhaps you
> > will find it
> > >> useful.
> > >>
> > >> keith
> > >>
> > >> 
> > >> On May 10, 2007, at 10:42 AM, balaji lakshmanan
> > wrote:
> > >>
> > >>> Hi all,
> > >>>
> > >>> I am fairly new to psychtoolbox but have some
> > konwledge oding in
> > >>> matlab.
> > >>>
> > >>> For one of our experiments we are trying to code
> > a stimuli whose
> > >>> display should consist of Concentric Rings
> > which expand and then
> > >>> contract.
> > >>>
> > >>> I also want to implement an attention task in to
> > this where subject
> > >>> have has to repsonse when the fixation cross
> > changes its color.
> > >>>
> > >>> Do anybody have any ideas or have done somehting
> > similar to the
> > >>> above explanined method. I especially would like
> > to get some ideas
> > >>> for the expanding and contracting concentric
> > circles part?
> > >>>
> > >>> Any help is greatly appreciated.
> > >>>
> > >>> Thanks a lot in advancne,
> > >>>
> > >>> Bala
> > >>
> > >> -----
> > >> Keith Schneider
> > >> Assistant Professor
> > >> Rochester Center for Brain Imaging
> > >> University of Rochester
> > >> Rochester, NY
> > >>
> > >
> > >
> > >
> > >
> > > Post your message to: psychtoolbox@yahoogroups.com
> > > Please indicate OS9, OSX, or WIN version, and
> > include your full name.
> > > Denis Pelli, David Brainard, and Allen Ingling.
> > > http://psychtoolbox.org
> > >
> > > Yahoo! Groups Links
> > >
> > >
> > >
> > >
> >
> >
>
>
>
>
>
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