Yes it's addictive, but you can say the same for coffee, facebook, watching porn, playing poker etc. It's not THAT addictive. Everything that it's pleasurable releases dopamine in the brain.
Regarding creativity: there are some studies that found that marijuana increases distance between associations (in Remote Associations Test which is one measure of creativity albeit one could argue if this is everything about creativity - it similar to inspection time - IQ correlation - it correlates but correlation is not complete of course). It also decreases latent inhibition which is good for creativity (but lower latent inhibition is also found in schizophrenia).
Cannabis has the effect of slightly increasing alpha-wave activity in the brain, and increasing blood flow into the right hemisphere, which is associated with holistic, nonlinear thought. Alpha waves, and right-brain thinking, are generally associated with meditative and relaxed states of consciousness, which are, in turn, often associated with creativity.
http://www.psycholog...-and-creativityhttp://santacruz.pat...oost-creativityBut I must also say this: even if it's true that marijuana boosts your creativity-tests scores, that doesn't mean you'll be more creative after you smoke a joint. Many people are full of ideas when intoxicated, but they are not in the state to put these ideas in reality. It may increase "creativity as a process" but it may not increase "creativity as a personality trait".
It's also possible that cannabis has different effects on different people - like piracetam, for example. It works for some people, but others may not feel anything.
Edited by hippocampus, 15 October 2012 - 07:34 PM.