http://www.pstnet.com/eprime.cfm E-Prime features a graphical "drag and drop" interface for creating simple experiments. For more complex experiments there is E-Basic scripting. Be sure to use E-Prime 2.0 as the older buggy 1.0 is also installed on many university PCs.
http://www.neurobs.com/ Presentation is able to deliver stimuli with millisecond timing accuracy. Presentation is very flexible and can be used to control nearly any behavioural experiment.
NBS training videos for Presentation are on YouTube at http://www.youtube.com/user/NBSTraining
Psychtoolbox (PTB) is a free set of Matlab functions. Psychtoolbox is installed on the Stimulus PC in the scanner suite.
The recommended environment for PTB is GNU Octave running on Ubuntu. PTB on MacOS is broken and no longer supported. August 2017 we moved the scanner stimulus PC to Ubuntu and Octave.
Update: PTB3.0.17 returns limited support for PTB on MacOS with Octave 6.1.
See Porting to Octave for help with common issues when converting from MATLAB.
Psychopy is a free stimulus program package with both graphical and text scripting. As of 12/2020 Psychopy does not work well with Ubuntu 20.04LTS. We have installed Psychopy on an Unbuntu 18.04LTS boot partition the on stimulus computer. Use 20.04 for PTB and 18.04 for Psychopy.