EPrime - motion stim issues

Wed Aug 24 21:17:53 UTC 2011

Thanks Paul - very helpful.

On Wed, Aug 24, 2011 at 3:20 PM, Paul Groot <pfc.groot at gmail.com> wrote:

> Hi Lisa,
>
> If you enter a numeric (hard coded) value into the duration properties
> of the wait1 to wait5 objects, you will indeed get fixed
> (non-randomized) intervals. Setting the ordering property of the list
> to random has no effect on this. There are several ways to get random
> duration values. The easiest way (=without any inline script) is to
> create a separate list and add an attribute with the interval values
> you would like to use. Set the ordering of this list to random (with
> or w/o replacement) and use this list as nested list in your real
> trial list. The name of the attribute (i.e. 'FootageInterval') can
> then be used to set the duration property in the wait objects. To make
> sure EPrime picks a new value from the nested list for each wait
> object you will have to use the following syntax for the durations:
>
> [FootageInterval:0]  (for duration Wait1)
> [FootageInterval:1]  (for duration Wait2)
> etc.
>
> Alternatively you could use a simple inline script at the start of the
> trial and use the E-Basic random() function to set durations. (That
> would be uniform random w/o replacement.)
>
> Hope this helps
> Paul
>
>
> 2011/8/24 Lisa Levinson <lml1934 at gmail.com>:
> > 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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