Yeah probably I'm too lazy to research it. I think the reason people think that weed is addictive is because there can be withdrawal symptoms.
Emotional and behavioral withdrawal symptoms may include:
-irritability
-restlessness or trouble sleeping
-fatigue and yawning
-depressed mood
-anger and aggression
-strange dreams
Physical withdrawal symptoms may include:
-appetite change
-nausea or stomach pain
-weight loss
-shakiness
-sweating
The reason for all of this is simple, the THC receptors in your brain are areas that influence pleasure, memory, concentration, sensory and time perception, and coordinated movement. If these parts of your brain are provided excess amounts of THC regularly then there won't REALLY be a physical dependency. Put in simple terms, you yourself just get used to being high, so regular living is a little different without it. In a sense, you bring the withdrawal symptoms on yourself because you don't realize that living is different when you aren't high.
It's just like dating a girl for like 3 years, then suddenly never seeing her again. You're used to goin to school and saying "hey!" and chatting it up, but now you aren't doing that so you're kinda like "wtf what should I do then?"