Using EBasic

[Michiel Spape]

Hi Vera, Lisa, list,
Just to add to this: it might be worthwhile to just make a screenshot (print-screen, open mspaint, hit paste) and take whatever stimuli you want out of matlab/presentation/etc and use those just as images in e-prime. I imagine that working with E-Prime makes it easier to implement your study in an ERP paradigm. If you want to pursue that path, I don't think your real issue is with programming, because you *should* be able to create the stimuli, isoluminant and whatnot, in photoshop or such. Once you have those (and I'm expecting you don't need millions of different stimuli in an ERP design), it should be a breeze to use these then in E-Prime. The more techy way to go about this is indeed using matlab, though as far as i know, you can't tell matlab or such to just make "grayscale, low contrast, isoluminant". Once you know the formulae behind such descriptions, I believe it shouldn't be too hard to just use photoshop or anything else (I think psychophysics people might want to kill me for making this statement, however). 

Of course,  if you do wish to pursue the 'make visuals on the fly' sort of path, you might find it helpful to have a look at PsychoPy (developed around here), which I'm sure should be fairly easy to work with as well. It has functions predefined (I think) for gabor-type stimuli and all the basic ingredients of the field of visual cognition (and others). Since it works on PCs as well, I guess you could even run it, make the stimuli, hit print-screen and get the experiment to run in E-Prime anyway. 

Best,
Mich

________________________________________
From: e-prime at googlegroups.com [e-prime at googlegroups.com] On Behalf Of David McFarlane [mcfarla9 at msu.edu]
Sent: 18 April 2011 20:23
To: E-Prime
Subject: Re: Using EBasic

Lisa,

As I recall, Presentation has some very nice high-level facilities
for generating complex and dynamic visual stimuli on the fly.  By
contrast, E-Prime has no such facilities.  EP can do some limited
things with text, for anything else it usually just presents image,
sound, or movie files.  But you can go beyond this with low-level
E-Basic code, for that you  would make extensive use of the methods
of the Canvas object -- see the Canvas topic in the online E-Basic
Help.  To do this well you would probably want to make a bunch of
custom subroutines or functions to recreate some of what Presentation
did for you -- for more on making subroutines and functions, you
might take a look at Chapter 4 of the User's Guide that came with
E-Prime, and more particularly work through the classic "VBA for Dummies".

Of course, you could just do this all back in Presentation, which you
know already does this; or even better, do this all in MATLAB using
the Psychophysics Toolbox, which has fantastic visual presentation support.

On an off-topic digression, I just learned about a new free
open-source cross-platform Python-based system called OpenSesame
(http://www.cogsci.nl/software/opensesame ).  Has anybody tried this,
and can comment on how it stacks up against E-Prime or other products?

-- David McFarlane, Professional Faultfinder


At 4/16/2011 03:11 PM Saturday, Lisa Levinson wrote:
>I am trying to replicate an event-related potential experiment that
>investigated the development of the magnocellular and parvocellular
>visual pathways. I am not looking to further study the development of
>these pathways, rather their correlation with other behavioral
>measures. The stims were originally programmed using the Presentation
>software language. I have attempted to create modified versions of the
>stims using Quark and Final Cut. I have generated the graphics and
>imported them into E-Studio but the major issue I am having concerns
>the parvocellular stim. If I can't control for luminance then I will
>potentially be eliciting a response from the magnocellular pathway as
>well.
>
>Using EBasic I was wondering if it would be possible to create
>"objects" such as a blue and green high frequency grating in which the
>colors are isoluminant with the background and low spacial frequency
>grayscale grating with a low luminance contrast. I have limited
>programming experience but can work with others who know Visual Basic
>for Applications. I am concerned though the psychophysical nature of
>these stims will not work with EPrime.
>
>Would greatly appreciate some input.

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