[visionegg] Re: visual attention task

Thanks.  I've started to look at the reference pages.  I would like a
document that describes the timing control process in plain english. 
I find the programmers manual and the reference pages are short.  I
find it a bit difficult to identify the object models and interactions
among the classes.  It would be nice to have a conceptual overview
with some diagrams of the flow control relationships.

I have a task that involves a central fixation point that is always
on.  In addition, we present a central cue stimulus for 50msec (over
the top of the fixation stimulus).  The cue looks like <> with one
half highlighted to direct visual attention to the left or right
visual field.  There is then a 1000msec interval and presentation of
an image for 300msec in the left or right visual field.  The image
presented is often a triangle (60% - common), sometimes the same
triangle rotated by 10 degrees to the right (20% - target) and
sometime it is a picture of something colorful (20% - novel).  The
task is to press a button whenever the rotated triangle appears in the
cued location (target).  The left/right visual fields are fixed
locations.  Each stimulus presentation is sequential (except for the
fixation, which is always on).

I don't know how to design/control this stimulus sequence properly in
the vision egg.  My learning curve has started with just presenting a
stimulus.  I then learned how to present different stimuli multiple
times and how to psedo-randomise the order of their presentation.  I
was able to learn that quickly, using the demo code for
"image_sequence_slow.py".  However, now I have a problem because my
task involves different stimulus durations and locations.

I was hoping that I could define some properties of the stimulus.  I
want to define a fixation stimulus with a central location and
infinite duration.  I want to define a cue left and cue right stimulus
with central location and 50msec duration.  I want to define the
common triangle and the target triangle stimuli,  so they have 300msec
duration and a location in the left or right visual field (ie, 4
stimulus definitions).  I also want to define a lot of 'novel' image
stimuli to also have left or right visual field location with 300msec
duration.  I would then like to arrange these stimuli in a sequence
and specify the timing of the sequence.

My first attempt at this is to create a list for the image sequence
and another list for each image duration, eg

imageList                    durationList
-------------                    ---------------
FIXATION                    fixation_msec
cue_left                       cue_msec
commonTriLeft            image_msec
cue_left                       cue_msec
commonTriRight          image_msec
cue_right                     cue_msec
novel01Right               image_msec
cue_left                       cue_msec
commonTriRight          image_msec
etc.

Note that there is a gap of 1000msec between the cue and the image. 
I'm not sure how to do that, but maybe it involves inserting an empty
image in the image sequence.

I hope that gives some idea of what the task is supposed to be.  I am
curious to learn the optimal way to design and control this task
sequence using the vision egg.

If I can work this out, I hope to be able to capture task responses
and to capture equipment signals on the serial or parallel port.  The
timing of the stimuli, responses and the equipment signals need to be
logged to a text file.

Best, Darren


On Wed, 16 Mar 2005 17:10:45 -0500, Mark Halko <mhalko@xxxxxx> wrote:
> 
> On Mar 16, 2005, at 12:45 PM, Darren Weber wrote:
> 
> > Can I get some feedback on this?  I would like to use the visionegg,
> > but the documentation is sparse and there has been no reply to my
> > posting on this list for several days.
> 
> The Library reference and the demos are the most useful ways to figure
> out how to do what you'd like to do.
> 
> http://www.visionegg.org/reference/index.html
> 
> > On Fri, 11 Mar 2005 15:40:18 -0800, Darren Weber
> > <darrenleeweber@xxxxxxxxx> wrote:
> >> Hi,
> >>
> >> I'm a visionegg newby.
> >>
> >> Please find attached a work in progress.  It will present a sequence
> >> of stimuli for a visual attention task.  However, I do not understand
> >> how to specify different stimulus durations for different stimuli in
> >> the sequence.
> 
> This is confusing.  Do you want images to randomly be different
> durations?  Or individual images have a duration assigned?
> Consider writing a function to select the duration of your image, and
> using it in put_image.
> 
> >> Also, I want to offset the location of the stimuli to
> >> the left and right of the visual field - how do I do that?
> 
> This was also confusing.  Do you mean you have two different locations
> a picture can appear in? Or do you want two pictures simultaneously?
> For the former, you can change the location of your TextureStimulus
> object stimulus by setting stimulus.parameters.position.  For the
> latter, you'll want to make two TextureStimulus objects, and place them
> in the viewport:
> viewport = Viewport(screen=screen, stimuli=[stimulus0,stimulus1])
> 
> Mark
> 
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