there was a study done here yeh, and the uni kids that did it got in A grade from the states. had to go through customs and shit, whole heap of legal crap that went on.
anyway, we did it as part of my psych course, and the study was done as long term smokers vs one timers. the long termers got a daily supply after going cold turkey for a week, the one timers just got it on the day.
the reaction time was the worst for hte one timers, and the best for the long term.