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 seems to work fine on intel macs. This software has been tested, and is used in our lab regularly with virtually no dropped frames. 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.
Once you download and expand the file, put it somewhere sensible (the same place as the directory for Psychtoolbox is probably a good place). Then just add the directory to your matlab path. Look at the readme and contents files for more information as to what is included and how to use it. Have fun, and feel free to contact me with questions and comments (sysadmin@shadlen.org).
The software for creating the dot stimuli on OS 9 macs can be found here.