Most anything can be psychologically addicting. Chewing your nails, food, etc, etc. I myself have an addictive personality, but have never gotten "addicted" to cannabis. The only time I had the feeling of addiction with cannabis is during a short time when I would smoke tobacco with my pot and I couldn't eat or sleep without it. Myself, I think this was linked to the tobacco more than the pot.
Over the last 8 years I've smoked for as long of periods as 2-3 years and quit cold turkey for a year with no ill effects apart from my sleep being affected. I just replaced with OTC sleeping pills. No withdrawals, affects in eating, nothing negative.
I know others who legitimately believe they've been addicted to pot but truth is most of them smoked it mixed with tobacco or had formed habits with it (smoking before a meal, before bed, etc).
Everyone is affected differently, so I would love to see more studies and research done on the topic in a non-biased way. That goes for the pro-legal and pro-prohibition types.