Could this perhaps just be a rationalization for some to play video games under a doctrine of "I'm getting smarter" when in turn it's just mindless consumption of media? I am all for FPS games improving my cognitive performance, but we should not be delusional about this.

If I wanted to (at least try) improving cognition, I would spend hours reading math textbooks and doing exercises, learning languages, perhaps reading about philosophy in my off-time; not strafing left and right with my WASD keys and trashing on kids all day in Counter-Strike.

Sounds like you already made up your mind.