In this episode of You Are Not So Smart David McRaney explores ego depletion and all the things that can cause it, from feeling rejection to holding back tears to avoiding the temptation of cookies.

One of my favorite tropes in fiction is the idea of the perfect thinker – the person who has shed all the baggage of being an emotional human being and could enjoy the freedom and glory of pure logic, if only he or she could feel joy.

Spock, Data, Seven of Nine, Sherlock Holmes, Mordin Solus, Austin James, The T-1000 – there are so many variations of the idea. In each fictional world, these beings accomplish amazing feats thanks to possessing cold reason devoid of all those squishy feelings. Not being very good at telling jokes or hanging out at parties are among their only weaknesses.

It's a nice fantasy, to imagine without emotions one could become super-rational and thus achieve things other people could not. It suggests that we often see emotion as a weakness, that many people wish they could be more Spockish. But the work of neuroscientists like Antonio Damasio suggests that such a thing would be a nightmare. In his book, "Decarte's Error" he describes patients who, because of an accident or a disorder, are no longer able to feel silly or annoyed or hateful or anything else. If they can, those feelings just graze them, never taking hold. Damasio explains that these patients, emotionally barren, are rendered powerless to choose a path in life. They can't ascribe value to anything. Their world is flat. Despite remaining very intelligent and able to carry on conversations, they no longer make good decisions. Former business owners will lose all their money on bad investments. People who used to work from home will become lost in constantly reorganizing their shelves. Not only are their decisions flawed, but reaching conclusions becomes an excruciating process. When Damasio handed one of these patients two pens, one red and one blue, and asked him to fill out a questionnaire, the man was lost. To choose red over blue using logic alone took about half an hour. Every pro and con was listed, every branching possibility of future outcomes considered. Damasio wrote that "when emotion is entirely left out of the reasoning picture, as happens in certain neurological conditions, reason turns out to be even more flawed than when emotion plays bad tricks on our decisions." Judgments and decisions corrupted by bias and passion are the only way we ever get anything done.

Choosing a blue pen instead of a red pen takes most people only a moment because the decision is driven by emotion alone. Try it now. Ask yourself which color ink you would prefer to use for the rest of this year. Why did you pick that color? The research suggests you feel your answer first, before you even know you've chosen, and then begin the work of rationally explaining yourself to yourself.

Psychology over the last 40 years or so has developed a model of the human mind in which our older and mostly unconscious system of emotions and hunches stands apart from our newer and mostly conscious system of rational, deliberate contemplation. Daniel Kahneman calls them system one and system two, fast and slow. Jonathan Haidt calls them the elephant and rider, and sometimes the master and the servant. Walter Mischel calls the interplay of these two complexes the hot/cool system. Every psychologist who supports the model has a favorite way of describing the two major branches of our minds – intuition and reason.

Not only have psychologists reframed how we see the collaboration of reason and intuition, but they've learned that the part of us that deliberates and contemplates, the part of us that Freud would have called the ego, can become exhausted. There is a body of evidence that reveals the conscious and rational system – the slow one, the rider of the elephant – gets tired very easily and eventually goes passive. Every deliberate act seems to weaken the ability to perform another. Eventually, you begin to give up earlier, to rush to conclusions sooner, and to eat things that you shouldn't. You watch movies on cable that you already own, censored and full of commercials, even though you could watch your own copy with minimal effort. You do things that seem very un-Spock-like.

If you think of these two systems as id and ego, the work of psychologist Roy Baumeister suggests that the ego sort of runs on an internal battery, one that can be drained after heavy use, but recharges after rest and reward. If you don't recharge it, you will find it difficult to keep your hand out of the cookie jar. He says that all sorts of things can lead to ego depletion, a state of mind in which your ego leaves its post and takes a nap, allowing the id and its emotions to take over. Depleted, you have poor willpower, self-control, volition, prosocial behavior, etc. Judges will even be less likely to grant parole until they've taken a break and eaten a sandwich.

In this episode we explore ego depletion and all the things that can cause it from feeling rejection to holding back tears to avoiding the temptation of cookies. Speaking of cookies…we also explore in this episode how psychologists have used cookies in novel ways to uncover the secrets of our minds. We examine the importance of cookies in psychological research from the work of Mischel to recent experiments that can cause normal people to steal confections and munch them like Cookie Monster in front of strangers.

In every episode, before I read a bit of self delusion news, I taste a cookie baked from a recipe sent in by a listener/reader. That listener/reader wins a signed copy of my new book, "You Are Now Less Dumb," and I post the recipe on the YANSS Pinterest page. This episode's winner is Jenne Bergstrom who submitted a recipe for Meyrick Cookies. Send your own recipes to david {at} youarenotsosmart.com.

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Image: Stains the dog abstains from cupcakes on "It's Me or The Dog" on Animal Planet