Note: This user manual is intended as a supplement to the information presented in the SOS article.  


The characteristics of stimuli used in an experiment critically determine the theoretical questions it can address.  Yet, there is relatively little methodological sophistication in how researchers select optimal sets of items, and most researchers still carry out this process by hand.  

To address this issue, we have developed SOS, an algorithm and software package for the Stochastic Optimization of Stimuli.  The algorithm rapidly and reliably finds stimuli that optimally satisfy the constraints imposed by an experimenter. This allows the experimenter to focus on selecting an optimization problem that suits their theoretical question and not on the tedious task of manually selecting stimuli.  

The software implementation of SOS and a user manual are provided free of charge for academic purposes as compiled binaries and as MATLAB source files.

Supported Systems

The software can in principle be run on all major operating systems.  Individuals who have MATLAB (version >= 2010a) installed may run SOS from the source code directly on any system.  For individuals without MATLAB, a standalone executable version of the software has been compiled for several operating systems.

The SOS graphical and console interface

Blair Armstrong, Christine Watson, David Plaut, 2011-2012