I stutter and smoke regularly, and I've found that low amounts of cannabis actually do help increase my fluency. There's a little bit of science behind it, but none that has looked directly at the correlation between cannabis and stuttering. This is my theory though, and the science behind it: We who stutter have a chemical imbalance in our brains involving serotonin and dopamine. The way these two work is that if you have high levels in one, you will have low levels in the other. Well, it's been found that in people who stutter, they seem to have excess amounts of dopamine in certain parts of their brain (http://www.stutteringhelp.org/medical-aspects-stuttering) and the best way to lower the levels of dopamine in the brain is to increase the levels of serotonin in the brain. Now, there has also been a study that found low doses of cannabis can actually increase serotonin, even though many associate marijuana use with an increase in dopamine. (http://www.sciencedaily.com/releases/2007/10/071023183937.htm) The study also says that once you get past a certain undetermined threshold (which will be different for each person based on tolerance levels and other factors) the cannabis will actually begin to produce more dopamine in the brain instead of serotonin, which in turn will decrease one's fluency if the theory that more dopamine in the brain corresponds with a lower level of fluency is true. For me, the science makes sense because I've personally experienced an increase in fluency after smoking a bowl or two with my friends, but anything more than that my fluency suffers, and can even drop lower than it is when I'm sober. For me, the perfect amount is one good, quality hit from a bong. It doesn't take much! just enough to ease your mind and create more serotonin in the brain. Serotonin eases anxiety as well, which will make you WANT to speak, which is something hard for many of us who stutter. To add to that, I personally think the cannabis aides in the formation of new thoughts, ideas, and associations, which again will make you WANT to speak instead of keeping all of these new thoughts and ideas to yourself because that's whats more comfortable, knowing that you won't stutter if you don't speak. Low amounts of cannabis have helped me and my stutter tremendously, both for fluency and confidence, so I encourage you and everyone else to try it. Vaporizers work really well too because you use a low amount that will be beneficial and is a healthy alternative to combustion. I hope this helps and if you have any questions let me know!