Vcrdm is a zip file containing a library of code for creating variable coherence random dot motion for visual experiments for use on OS X macs using the latest Psychtoolbox software. It is based on the dots patches originally created by Tony Movshon, and was created by Maria Mckinley, who currently works in the lab of Michael Shadlen. This software has not yet been tested on intel macs. This software has been tested, but probably not vigorously enough (iow, use at own risk), on powerpc macs. It is pretty well documented. It includes software for making the dot patches and targets, as well as a full experiment procedure for a keypress motion discrimination task. I have removed the Kill and StartUpdateProcess commands, as they are not necessary in newer versions of OS X. If you are using something older than 10.4.4 tiger, make sure that the automatic software update for the mac is turned off in preferences, or it could pop up in the middle of an experiment.
The software for creating the dot stimuli on OS 9 macs can be found here.