The Emotion/Rationality Fallacy
Plato used an allegory of a chariot to describe the human soul. In the allegory a charioteer drives a chariot pulled by two winged horses. The charioteer represents reason, while the horses represent emotions and primal desires. This conflict - between reason on one side and emotion and desire on the other - continues to resonate as a metaphor for decision-making. There's just one problem: this is not actually how the brain works.
As Lisa Feldman Barrett put it in Seven and a Half Lessons about the brain:
But human brains don't work that way. Bad behavior doesn't come from ancient and unbridled inner beasts. Good behavior is not the result of rationality. And rationality and emotion are not at war... they do not even live in separate parts of the brain.
This is relevant for chess players because we're always trying to make better decisions at the board. Chess is often seen as a supremely rational struggle, especially by non-chess players. (Those who play competitive chess know that the struggle is intensely emotional as well.) If you're caught in the Plato charioteer metaphor, it might seem that becoming less emotional would make you a better player, but in fact, you can't turn off your emotions, and if you could that would be very bad news.
Neuroscientist Antonio Damasio described interacting with a patient whose emotional function had been impaired as a result of brain damage. If you asked the patient where he wanted to go for dinner, he would start listing pros and cons:
This restaurant has been empty lately, so the food is probably not that good... Then again, it will probably be easier to get a table...
Left to his own devices, he would go on like this indefinitely, listing reasons on both sides but never making a decision. As Damasio put it, he lacked the emotional "lift" to finally decide.
The patient's indecisiveness about restaurants closely resembles a chess player who struggles with time management. She can list pros and cons forever, but never make a decision. If you asked her after the game, "Was it rational to spend 60 minutes on that move? Did that time usage maximize your chances of winning the game?" she would have to answer, "No, of course not."
In this case, emotion is not opposed to rational decision-making, but actually essential for making a good decision. If the player had an emotional connection with one move and played it quickly, even if it wasn't the perfect move, she would have used her time more rationally, in the sense of maximizing the chances of a good result in the game.
Rather than trying to eliminate or minimize emotions, it's better to try to properly calibrate your emotions. By calibrate, I mean that the intensity and focus of your emotions are appropriate for what you're trying to accomplish. Chess coach Dan Heisman has an interesting theory that strong players are appropriately upset after losses. The idea is that if you really don't care about losing at all, you have no incentive to get better; but if you hate losing too much, you might find the inevitable losses that are part of chess so painful that you quit altogether. In fact, many players do quit chess because they can't handle the pain of losing. There is something to this idea of moderating your discomfort, but it still assumes that your emotions are primarily tied to winning and losing.
There's another way, which I learned from watching strong poker players. In poker, even more than in chess, it's essential not to get too tied up with short-term results. The reason for this is that in chess, you mostly get the result you deserve: if you outplay your opponent, you usually win; if you get outplayed, you usually lose. In poker this isn't true at all. The luck element dominates the skill in the short-term. It's very easy to play well and lose, or play terribly and win. Only in the long-term does superior skill win out. Tying your emotions or decisions to short-term results is catastrophic because you'll just be chasing randomness.
So how do the best poker players deal with this? They don't make themselves into affectless robots. While playing, they're clearly emotionally invested in the game, but their emotions aren't tied to winning and losing. While beginning players think, "I hope I win this hand," or, "I hope he doesn't make a big bet," great players think, "What would the best hands to bluff with be here?" or "Should I usually check or bet with my strongest hands in this spot?"
In other words, their emotions are tied to curiosity about what's really going on strategically in the spot they're in, not whether they're going to win or lose the hand. This is a much more sustainable form of emotional engagement. In chess if you're playing against an appropriate level of competition, your wins and losses should be split somewhere around 50/50. If every loss makes you furious and every win makes you elated, you'll be on a rollercoaster ride that makes it really hard to work on your chess consistently. One of my favorite poker quotes comes from coach Tommy Angelo:
"The three main causes of tilt are winning, losing, and breaking even."
That is, if your emotions are tied to results, every result is an excuse to get off track. In contrast, it's possible to be curious in every game, win, lose, or draw. You'll still prefer winning to losing and probably be upset when you lose, but if you're genuinely curious about what was going on in the game, you can take pleasure from analyzing even the games you lose.
To wrap up, emotions are not the enemy of rationality. You can't eliminate emotions, and if you could, it would probably be disastrous for your decision-making. Instead, tether your emotions to something useful and sustainable: curiosity about how chess really works.