Positive thinking gives you an edge every time a person is gambling. Base on my experience, every time that you have doubts on your card, no matter how strong it is, you will end up losing the game because you are not confident. Especially in the game of poker, the other player will definitely feel that you are bluffing if you're not confident. You are also willing to take the risk if you are thinking positive, the more you try, the more chances of winning.
Do you mean pretending? I think it's what you mean, and not about "positive thinking".In card games, it's what you do most of the time, you hide the expressions in your face so your opponents cannot see your tactics.
I still believe that positive thinking has no effect in winning or losing. It could make you feel comfortable but won't add any "mojo" to your game.
.The way some people have taken gambling and believing they can just find a way to get on the better side of winning is amazing and at the same time preposterous. We call it gambling, and it is all about luck and I wonder why some would just want to screw themselves with some bullshit mentality of winning because they could think positively.