Eprime - Coherent Motion Stimuli?

[Paul Gr]

Hi James,

There are a few option to do this. One way is to create a DLL, which 
contains fast code (for example C++) to create your graphics on the fly. A 
few months ago I programmed such a DLL to create ellipses containing 
gradiently filled color patterns. The complete source and EPrime example 
script is available from http://www.psy.vu.nl/download/paul/stimmaker.zip 
The DLL was programmed with Visual C++.

Another option is to create a custom application which creates a series of 
bitmaps before running EPrime. I also have such an application available 
which was programmed in Visual Basic .NET. This program was made for someone 
who required a series of bitmaps that contained a grid of small dots moving 
around their center position. Most of the dots move at random, but in some 
rectangular area's on the screen the dot's move with a specific frequency. I 
could also provide the sources of this program (not very well programmed 
though!) Just let me know...

kind regards,
Paul Groot
Vrije Universiteit Amsterdam
The Netherlands




>From: James Intriligator <j.intriligator at bangor.ac.uk>
>To: E-Prime Listserv <eprime at mail.talkbank.org>
>Subject: Eprime - Coherent Motion Stimuli?
>Date: Wed, 14 Sep 2005 18:56:01 +0100
>
>Hello ePrime-ers.
>   I am getting ready to do some coherent-motion experiments (description
>below)
>   In the past I have written stuff in c to generate these stimuli (on a 
>Mac)
>   Now, for various reasons, I am considering trying to do them in ePrime.
>    I am either going to be brave and try to have ePrime generate these
>on-the-fly OR I might have to have ePrime create a series of BMP files
>(before each trial) and then have them shown like a flipbook in the trial.
>   Questions:
>   (a) anyone tried this before?
>   (b) Any source-code you might be willing to share?
>   (c) any other thoughts/advice?
>
>  thanks in advance,
>    james
>
>Coherent-motion displays:
>   imagine you have 1000 dots moving on the screen ‹ if 500 are moving
>³coherently² to the right, and the other 500 are moving in random
>directions, then this is said to be ³50% coherent to the right².  If 200
>dots are moving to the left and the remaining 800 are moving in random
>directions then this is ³20% coherent leftward².
>
>------------------------------------------------
>James Intriligator, PhD
>Senior Lecturer
>
>School of Psychology - Experimental Consumer Psychology
>University of Wales - Bangor
>Brigantia Building - Room 328
>Bangor, Gwynedd LL57 2AS
>Wales, UK
>
>Tel: +44 (0)1248 383630
>Fax: +44 (0)1248 382599
>email: j.intriligator at bangor.ac.uk
>------------------------------------------------
>
>