"Effects of nicotine on perceptual speed" [1] is behind a paywall, and I can't tell from the abstract whether the results also apply to non-smokers.
However, the abstract of another of the articles, "Effects of Cigarette Smoking on Performance in a Simulated Driving Task" [2] states that the effect was only measured on minimally abstinent smokers.
Are any of the other studies measuring the beneficial effects of nicotine on non-users (and non-users only)?
My anecdotal experience when I quit (the first 2 times, couple of months each) as well as the first time I smoked was that the first couple of cigarettes had absolutely no effects, whatsoever.
So the last time I quit (about 2 years ago), I just kept at it. After about 3 months any previously observable decline in performance and ability to focus was gone. Most of it was gone in the first 3 weeks actually, with only slight remains of increased irritability persisting for 2 more months.
That makes me suspect that nicotine only has a beneficial effects on nicotine users (instead, lack of nicotine is what causes the opposite of the measured effect for users).
But even if such benefits exist, I feel that the they aren't worth it. The inability to function without nicotine, the constant drive to get more - it feels like slavery, and I'll never go back to that.
And I cringe when I read things like:
There is addiction but it’s drastically overestimated by
almost everyone and may been conflated with the habit-formation
capability
Because in my experience its completely, totally wrong. I could clearly separate 2 phases that I went through when I quit:
1. the nicotine desire phase - First 48 hours. Incredibly, painfully hard. Strong desire to place a sticker on me or just light a cigarette and make it all go away. This is what kept me a user for 7 years and helped me come up with various excuses just to continue.
2. The learning-to-live phase: A hard but somewhat joyful period where I would recognize the habitual desire to light up a cigarette associated with various activities.
The second phase had 3 different stages for every smoking habit I have developed. For example, at first I couldn't imagine drinking coffee without a cigarette.
Then after the first time it felt like I'm getting no joy from the coffee. The second time it felt okay, but slightly incomplete. Finally, the third time it was all good.
The awesome part was realizing that I just learned how to drink coffee without cigarettes. And it was super-easy: just do it 3 times. Joy! Repeat with all other problematic activities.
This happened with all activities that I associated with smoking. Removing the habits felt easy. Getting off the nicotine felt almost impossible. Luckily, the necessary time for the second one was much shorter (I still had tiny activity-induced cravings couple of months after I quit)
[1]: http://cercor.oxfordjournals.org/content/19/9/1990.abstract
[2]: http://www.karger.com/Article/Abstract/119229