I sometimes think of the brain as a muscle rather than a computer. A muscle gets tired; so does the brain. A computer doesn’t. A computer can perform multiple tasks simultaneously. A muscle can’t; nor can the brain.
When a muscle gets tired, its performance degrades. After a long hard bike ride, I need to rest and replenish. My muscles need to recover. Until they do, I’m a weakling.
Our brains work the same way. Did you ever have that burnt out feeling? It’s your brain telling you that it needs a break. Take it easy. Give it a rest. Don’t make a big decision when you’re tired – your IQ is too low.
You probably have a good idea of what it takes to overwork your muscles. You know when to stop. But do you know what it feels like to overwork your brain? Here are some clues.
Your mental performance declines when:
You’re dealing with scarcity – when something we value is scarce, we use some of our brainpower trying to replenish it. That leaves less brainpower available for complex thought. As a result, we make poorer choices in other domains. Do you know anyone who has made a string of bad decisions? Perhaps he’s dealing with scarcity in some part of his life.
You’re hungry – conscious thought consumes huge amounts of energy, mainly in the form of glucose. If you’re short on energy-producing nutrients, you can’t think clearly. You’re more likely to argue with your spouse when you’re hungry. Drink a glass of lemonade and you’re less likely to bicker.
You’re sleepy – when you’re sleepy, you can’t focus. You can’t keep a moving train of thought. You can’t filter out random ideas. I do my best thinking in the morning. On the other hand, I’m more creative in the evening, precisely because I can’t filter out random ideas.
Your willpower is low – conscious thought is often described as effortful. Just like physical exercise, it takes willpower to exercise your brain. Willpower is like a muscle, too. If you use up a lot of willpower by resisting the temptation to, say, smoke a cigarette, you’ll have less willpower left to do the heavy lifting of thinking. Your IQ sinks.
Your heuristics trip you up – we all use shortcuts, called heuristics, to get through the day. Think of them as habits of the mind. Mental habits save me time and energy. And, most often, they work. But they’re prone to certain biases – like confirmation bias, availability bias, stereotyping, and satisficing. If I’m not aware of my biases and don’t correct for them, my IQ drops significantly.
You’re seduced by timeworn stories – I counsel my clients to tell stories to explain complex phenomena. But the economist, Tyler Cowen, points out that the stories we tell vastly oversimplify a complex and messy world. Even so, we love our stories; they’re very comforting. The good-versus-evil story is especially hard to resist. We love its ability to explain the world around us. But is it true? Probably not. Cowen claims that our IQ drops by ten points when we’re seduced by an overly simple good-versus-evil story.
I could go on. Your mental performance drops when you’re angry. Or dehydrated. Some people think cholesterol-reducing drugs – statins — can lower your brainpower. Your brain, after all, is made up mainly of cholesterol. But the science isn’t settled. Here’s an article that says you’re dumber on statins. Here’s an article that says the opposite.
So what to do? Eat right, get plenty of sleep, identify your biases, and work on your willpower. Be suspicious of stories that oversimplify the world, especially if they’re seductive. If that doesn’t work for you, try taking my class on critical thinking.
How To Lower Your IQ in 15 Minutes