at very high level you don't need a lot to turn the tables. a sign of when to act agressive/defensive could be enough. I can think of millions ways to give this sign.
Yes. This can't be overstated enough. Cheating doesn't require concealed computers or any sort of electronic communication at all.
People might scoff but honestly, chess players have worried about this sort of stuff for decades. The '78 world championship between Karpov and Korchnoi for example, is a lesson in this kind of cheating - I'm thinking of the yogurt controversy in particular.
I don't believe for a moment that Karpov or his team were cheating in '78 (at least not in that way) but the fact that they weren't is really the salient point - it is very difficult to ignore the idea that your opponent might be cheating once the possibility has been suggested.
That is to say, trust in your opponent is a very important element of competitive play.
People might scoff but honestly, chess players have worried about this sort of stuff for decades. The '78 world championship between Karpov and Korchnoi for example, is a lesson in this kind of cheating - I'm thinking of the yogurt controversy in particular.
I don't believe for a moment that Karpov or his team were cheating in '78 (at least not in that way) but the fact that they weren't is really the salient point - it is very difficult to ignore the idea that your opponent might be cheating once the possibility has been suggested.
That is to say, trust in your opponent is a very important element of competitive play.