EPrime - motion stim issues

Tue Aug 23 23:06:57 UTC 2011

Paul-

I have worked out a script that seems to run properly. Rather than use a
still/jpeg file between motion files I added a "wait" slide. So, my gradient
runs for 100ms and the wait slide follows allowing me to present a
non-moving image of the gradient for a specified duration. Note: in order
for the animation to run as a loop I have five motion files, loaded in
sequence. Here is my next challenge...I need five wait slides between my
motion files but I would like to randomly assign a duration to those wait
slides. At the moment I have them set up so that wait1 runs for 1000ms,
wait2 for 600ms, wait3 for 700ms, wait4 for 800ms and wait5 for 900ms. This
list is set for random but I am not exactly sure what I am getting. Do you
think wait1 will always run at 1000ms, wait 2 for 600ms, etc?

Lisa

On Thu, Aug 18, 2011 at 7:04 PM, Paul Groot <pfc.groot at gmail.com> wrote:

> Hi Lisa,
>
> It looks like this 'hybrid' movie/still solution is causing more
> problems than it solves. Like Presentation, you probably would like to
> use some script to create/present the graphics. Unfortunately, E-Basic
> only has limited support for creating graphics on the fly (text,
> lines, rectangles and ellipses), and I'm not sure if your stimuli
> could be drawn by those primitives. However, pre-created static
> bitmaps (as movies) can be a workaround for painting more complex
> graphics objects. Programming moving objects is not extremely
> difficult, and if I remember correctly, there is an example available
> on the pst support site
> (http://www.pstnet.com/support/samples.asp?Mode=View&SampleID=8)  When
> the graphics objects themself change, you might run into difficulties
> when the computer hardware cannot keep up with the number of required
> bitmaps and desired frame rate. Using movies will probably the only
> working solution in that case. I think I would include the ISI's in
> the movie so it becomes a single file that can be played without
> interruption. ISI durations cannot be set at runtime this way, unless
> you use the technique described below.
>
> In some cases is also possible to use an external (DLL) library to
> create complex stimuli at run time (gabor patches, gradient fills,
> ...). Such an external library could be used to create bitmaps or
> movies on the fly, which then can be loaded by eprime.  However, this
> requires in-depth knowledge of a programming language such as C++
> because such a specific library probably doesn't exist yet.  I used
> this technique before to create audio files and complex bitmap
> sequences. (If you have EPrime version 1, you might have a look at the
> attached example. This will display a changing ellipse with a gradient
> fill that can be defined at runtime in EPrime)
>
> Best,
> Paul
>
> 2011/8/18 Lisa Levinson <lml1934 at gmail.com>:
> > Yes, Presentation is better for this type of experiment, however, the
> > Presentation script was generated in a different lab and the lab I am
> > working in is not set up to use Presentation (requires a serial port
> > connection for which we have had issues with timing). So, you are 100%
> > correct, I have been jumping through complicated hoops for more time than
> I
> > will admit and while I have made progress the motion stim for this
> > experiment is just crazy difficult to figure out. Today I was going to
> > attempt to increase the duration of stimulus presentation to see if it is
> a
> > loading issue. Will let you know but any thoughts would be greatly
> > appreciated.
> >
> >
> > On Thu, Aug 18, 2011 at 1:26 PM, David McFarlane <mcfarla9 at msu.edu>
> wrote:
> >>
> >> Lisa,
> >>
> >> OK, I will ask the obvious dumb question.  If you already have a program
> >> that works in Presentation, why would you want to recreate it in
> E-Prime?
> >>  Although in principle E-Prime should be able to handle this, it may
> require
> >> jumping through a lot of complicated hoops, and it seems to me that
> >> Presentation makes a better platform for this type of task.
> >>
> >> -- David McFarlane, Professional Faultfinder
> >>
> >>
> >> At 8/16/2011 11:24 PM Tuesday, you wrote:
> >>>
> >>> I am looking to replicate an experiment originally created in
> >>> Presentation for use with EPrime, part of an EEG experiment. The
> original
> >>> experiment used that software’s programming language to create a color
> and
> >>> motion stimulus that allowed the researchers to compare the
> parvocellular
> >>> and magnocellular visual pathways. I do not know EBasic and so I have
> >>> created the color stim in Photoshop and imported the image as a slide.
> While
> >>> I am not able to control luminance it appears very close to the
> original.
> >>> The motion stim is proving much more complicated. I created a
> vertically
> >>> oriented sinusoidal spatial frequency grating as an animation file in
> Final
> >>> Cut (editing software) and have been struggling ever since to make it
> work
> >>> as intended.
> >>>
> >>> The experiment calls for a low frequency grating to traverse from left
> to
> >>> right for 100ms with inter-stimulus intervals anywhere from 500 ms to
> >>> 1000ms. Because the stimulus presentation is so short I don’t seem to
> be
> >>> able to use the video start/stop feature; additionally, randomizing the
> ISI
> >>> is not possible using this feature. I determined that one cycle of the
> >>> animation sequence is 31 frames and with a 60 frame per second
> animation
> >>> that means that I have 10 six frame sets per second (each set 100ms). I
> then
> >>> created 6 frame .avi files and loaded them sequentially. Because the
> >>> experiment calls for 320 trials I had the choice to load 320 files or
> create
> >>> a loop with 5 six frame sets, I opted for the loop. To allow for the
> >>> randomized ISI intervals I created jpeg files containing the final
> frame of
> >>> each set and then finished the sequence with my one remaining frame (5
> six
> >>> frame sets plus one final still, making 31 frames).
> >>>
> >>> After loading the movie/still files (sequentially) it seems that even
> >>> though the stills(jpegs) were captured from the animation frames they
> are
> >>> not similar in size, so I have an inconsistency there – issue one. The
> other
> >>> issue is that the two images (movie/still) overlap rather than
> following in
> >>> sequence. One appears inside the other and the error message I get once
> I
> >>> abort is “unable to update frame.” I did eliminate the 500ms ISI but
> that
> >>> has not helped. I also tried to eliminated the jpeg files but then I
> can
> >>> only randomize the duration of the motion which should be consistent at
> >>> 100ms intervals. It is the time between presentations that should
> randomly
> >>> fall within 500 to 100ms.
> >>>
> >>> I am at a complete loss as to what to try next. HELP!
> >>
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