I have done a few in-depth searches and have not found any experiments which appear to be scientifically rigorous and fully unbiased- a discussion of this can be found in this paper
, and a few other sources can also be found at the bottom of the article. Many of these sources can also be found in the Wikipedia article, as mentioned by John Dreher above.
However, I haven't had the time to do a complete search- you could try checking at this site
for scientific articles, as a Google search seems to return mostly unreliable, commercial articles and sites. If I find anything further, I'll post it here.
Good luck with this project!