I think you're right about chess, and Ovid's right about Perl. In Ovid's particular Kung Fu experience, he was kicking in practice but not actually making contact - but once he experienced contact, he learned. In Perl, when you write CGIs it's typically without immediately getting hacked. Once you are hacked, then you can get your feedback to learn from; in the meantime, you can be happily strictless and tainted. Chess, on the other hand, you relatively immediately get your feedback when you screw up, and in a big way (zero-sum games are good for that sort of learning), and from the outset you face the entire task in a combative frame of mind that encourages thinking defensively. Most people don't learn to program that way. Ovid's point is that if they're going to do CGI work for businesses, they should.

In any case, I think the point stands that bad chess means you lose in game play, but bad CGI code means everyone with a credit card on your site may lose, and in real life.

Concerning the brain: imho, you're more-or-less right on when it comes to raw acquisition of data, but there is unquestionably interference at the level of mapping that data onto actions, even or especially for abstract 'actions' like making a mental judgement or categorization. And then there's selective blindness - where things that you've learned prevent you from even noticing the things you ought to be learning. Bringing it back to programming, I'm certainly aware of a few personal coding and thinking habits -- not on the same order of magnitude as smoking, naturally -- that have been derailing me lately. Fixing these habits is a process of learning the right thing so well that it swamps the bad habits; to me, the distinction between that and "unlearning" is largely semantic. Maybe you don't have the same experiences (in which case, you're a genuinely lucky man) but I'd propose that a lot of people do.

-- Frag.