true speak: Marijuana may be a short cut to the imagination. For me it is good for the contemplation phase of creating; Good for pulling ideas from everyday life and jotting them down without any form whatsoever.
What I find more affective at unblocking the blocked artist is deadlines. Not the type of deadlines that you impose upon yourself. Those are easily broken. Someone has to impose a deadline on you so there is a sense of embarrassment if you don't get the work done.
A glass of Pinot Noir after the work is turned in helps to sooth the doubt. create. enjoy. create again.