Really good study, but it looks like the only things with a stronger correlation than attention control score and resting pupil size was caffeine and nicotine.

And it's concerning so many participants couldn't verify nicotine/caffeine consumption when those are the biggest connections when they disclose their sample was "moderate".

We'd also have to get into how nicotine/caffeine would be "performance enhancing" for these kinds of tests, yet would make the pupils contract. They should have tossed the participants who couldn't report nicotine/caffeine instead of including them.

But ideally it would have just been participants who had abstained from either for 24 hours. Good luck with that tho.