The stop-signal paradigm is a useful tool for the investigation of response inhibition (for a review, see Verbruggen & Logan, 2008). Recently, Gordon Logan, Michael Stevens and I developed a free program, called STOP-IT, for running the stop-signal task.

STOP-IT can be installed on computers running Windows 2000/XP, is available under the GNU General Public License and can be download here.

(We strongly advise users to read the instruction file, which can be found in the Startup folder, after installing the program.)

The main advantage of STOP-IT is that it is a precompiled executable and for basic use there is no need for additional programming. In addition, we also offer an analyzing program, called ANALYZE-IT. ANALYZE-IT can also be used out of the box and is automatically installed during the installation of STOP-IT. This second program allows users to estimate SSRT for every subject and it will calculate the means for all dependent variables of interest.

Check the Instruction file to see if you have the most recent version.

You can reward the STOP-IT developers for their effort by referring to the Behavior Research Methods article that describes STOP-IT. Here's the reference:

Verbruggen, F., Logan, G.D., & Stevens, M.A. (2008). STOP-IT: Windows executable software for the stop-signal paradigm. Behavior Research Methods, 40 (2), 479-483 (pdf of the article)