Jon Peirce was responsible for the creation of the bulk of the code in PsychoPy. The project arose out of a belief that programming psychophysics could, and should, be easier (in terms of writing fewer lines of code per experiment). If you use PsychoPy please acknowledge his efforts by citing the paper describing the library:

Peirce, JW (2007) PsychoPy-Psychophysics software in Python.
J Neurosci Methods, 162(1-2):8-13

Psychtoolbox had already done a huge amount in making things easier, but was tied to Matlab which I find expensive and not as clean as Python. Also Matlab doesn't have a proper wrapper around OpenGL, so writing the equivalent code would require a great deal of C source as well which I didn't relish :) Suffice to say that PsychToolbox was a big influencing factor in the way PsychoPy was written. Thanks David Brainard, Denis Pelli and Allen Ingling for that.

Also thanks to Andrew Straw who was writing VisionEgg at a similar time. He and I were aiming for different markets somewhat, but he has been very helpful in discussions at different times and some of his code might get incorporated into PsychoPy at some point (C extensions such as increasing thread priority and checking monitor refresh rates).

Thanks also to the University of Nottingham and the BBSRC for their support of the project.