Rationality is the process of coming to correct beliefs. Correct beliefs turn out to be really important. Being correct about how the world works gives you a huge advantage in achieving your goals. No matter what you want to do in life, becoming more rational will help you do it. Wouldn’t you like being right more often? Seriously, who likes being wrong all the time? Rationality is about being right, and being right is pretty damn indispensable.

Unfortunately, there are hundreds of scientifically documented errors in thinking that all humans make called cognitive biases. A cognitive bias is a predictable error your brain makes. Unfortunately, your brain doesn’t say to you, “Hey, I’m systematically giving you horrible information”… to someone without rationality training, it looks exactly like information from anywhere else in your mind. You don’t notice anything is wrong. Often it’s easier for an outside observer to notice. You ever notice how you have all this great advice you wish your friends would listen to? It’s obvious to you that they’re making poor decisions in their lives but they can never see it. A lot of those sub-optimal decisions are caused by biases clouding their judgement.

The trouble is that you suffer from cognitive biases too. You make predictable errors in reasoning, beliefs, and life decisions as well. These errors pile up and are causing you to get sub-optimal life outcomes. So where can you try to counteract these effects?

One place you can start is with overconfidence bias. Overconfidence causes people to consistently overrate their own judgment and performance. In controlled psychological experiments, researchers who asked participants trivia questions found that people commonly report being “100% certain” only to turn out to be right only 40% of the time. Furthermore, even people who are told about overconfidence bias who are tested again only improve to 50% accuracy while remaining 100% certain! This has numerous implications for how to play poker.

If you’re unaware of overconfidence in poker, you’ll keep making lots of poor decisions. You’ll be “100% certain” your opponent does or doesn’t have a hand. You’ll call off a lot of money trying to win tiny pots or fold far too often to relatively tiny bets until you adjust your actions. Reducing overconfidence bias is just one form of rationality training that happens automatically as you adapt to become a winning player. Having a training ground like poker gives you an arena where you can feel what overconfidence is like, learn to spot it, and actually modify your behavior in the moment to route around it. Knowing your pot odds is useless if the judgement you use when weighing those odds to is systematically biased. As you gain experience in poker, you learn to spot the difference between the flawed, biased signals that lead to overconfidence and adjust your reasoning to have the correct amount of confidence to fit the facts.