 I get nervous when I have a doctor who spits out a diagnosis without a second thought. I appreciate the confidence, but I prefer my healthcare provider to have some patients. One of my favorite feel-good TV shows is a Japanese series called Old Enough, where very young and very cute children execute fairly involved errands for their parents, shadowed by a camera crew wearing disguises that would only fool a five-year-old. It's clear that kids aren't chosen to appear on the show at random, but it's still astonishing watching any two-year-old walk a couple kilometers to the supermarket, buy groceries, and carry them back to his powder mother. I'm always struck by how persistent, resourceful, and clever these youngsters can be, a four-year-old patiently figuring out how to swivel a cabbage as big as she is out of the ground over the course of an hour, a little boy whose arms get tired carrying firewood until he realizes he can pull it in its bag like a sled. Usually, whenever we see kids trying to puzzle their way through challenges that are trivial for adults, it's common practice to step in and demonstrate the solution, or to simply do it for them. But the show's framing, however contrived, supplies an environment with two resources children don't usually get to practice their problem-solving skills, autonomy and time. It feels weirdly dissonant to watch a young child developing a very simple solution over the course of hours, and to still find myself impressed at how clearly brilliant they are. A lot of importance is assigned to speed when it comes to mental phenomena, readily apparent from the impressive number of metaphors for mental acuity, like quick-witted, a fast learner, up-to-speed, nimble, whiz, or just plain slow. Many of the criteria we use to evaluate someone's intellectual or cognitive virtues explicitly measure how fast they can figure things out. Psychology and neuroscience are chock-full of psychometric measures that take the form of either time attacks, like solve as many of these problems as you can in 10 minutes, or time trials, where you have a limited window to get the highest possible score on a set of questions. It's easy to guess why mental speed might have become the go-to yardstick for intelligence. Ranking people by who can achieve a particular goal first is super easy to measure and unambiguous, a continuous variable that will probably have a normal distribution, which sidesteps the sticky problem of defining what it is exactly that we're trying to measure. Thus, if the dualist point of view is right, that is, if only those beings whose behavior implies the actions of an irreducible autonomous, i.e., self-regulatory soul, can be called intelligent, can't we just read some numbers off a stopwatch or something? Some theorists actually assert that mental speed is the basic process underlying individual differences in intelligence, that, barring serious deficits, any advantage or disadvantage in someone's capacity for reasoning can be chalked up to how fast they can think. According to these models, there may be some other stuff going on around their periphery, but when you come right down to it, some people's mental CPUs are just doing more operations per second, and those people are generally going to perform better in cognitive tasks. Of course, brains aren't CPUs, and thinking is a little more nuanced than operations per second. As you can tell from the title of this paper from Lazar Stankov and Richard Roberts, some psychologists find that whole idea misguided. In fact, as they walk through all the problems with a reductive equation of intelligence with mental speed, they end up blowing a substantial hole in the idea that speed is a good yardstick for almost any cognitive phenomena we might care about. First, there's the problem of treating mental speed as a single meaningful thing. There are several mental processes that sit between the appearance of a problem and someone slamming their pencil down after having solved it. Attention, perception, analysis, decision, execution. Any of these steps may be performed fast or slow. You might be a speedy reader, or a quicket deciding on an answer once you understand the question, or prone to being distracted by other things you find more interesting or important. Any of these tendencies would have a pronounced effect on the time it took you to solve a problem once presented, and it's not clear that they have much to do with intelligence per se. There's very little correlation between different factors of mental speed. People who have quick physical reflexes don't tend to be any faster at parsing or analyzing questions than anyone else. Also, as anyone who's tried to read a dense email before their morning coffee can tell you, there's a fair amount of speed variation within individuals. All this makes it hard to say that the group of phenomena we label as mental speed is a meaningful category. It's kind of like saying there's 15.4 gallons of liquid in this car if you add up the gas tank, the water fluid, the oil, and the drink and the cup holder. Even if we were to just mush everything together and hope that individual variations and different kinds of mental speed would get smoothed out by sheer numbers, when we compare time trials to other untimed measures, speed only seems to be responsible for, at most, around 25% of the variance in test results. That's not nothing, but it's not a lot for a property that's supposed to be driving those differences. There's also evidence that general intelligence is taxed more by challenges that aren't about speed, a fact that should be evident to anyone who's experienced testing anxiety. If you want to see how well someone can perform fairly simple cognitive tasks under pressure, a speeded test would be a useful tool. But if you want to gauge their full capacity for insight, careful reasoning, and creative problem solving in complex scenarios, you'll probably get a better idea of that potential if they have as much time as they need to reflect and formulate the best possible answer. Like, consider, add as many of these two-digit numbers as you can in five minutes, versus build me the strongest bridge you can out of spaghetti and marshmallows. Which do you think will give a better indication of the full extent of someone's mental strengths? So, mental speed probably isn't a basic process underlying individual differences in intelligence. There's a number of good reasons to question its privileged status in our conception of intelligence in the first place. If you pull in a thread a bit, a number of otherwise normal practices start to look a little strange. Which kids get kudos and attention in the classroom, the ones who reliably figure out an answer, eventually, or the ones who have their hands up first? Do schools reward students who carefully pick apart assumptions, investigate contacts, explore alternatives, and take their time thinking through implications, or those who can blast through 50 multiple-choice questions without blinking? Is it more important to academic success to absorb information quickly and retain it for decades? What do conditions like dyslexia and dyspraxia do to wildly intelligent people who need a little extra time to read or to write down an answer? Who tends to get noticed and promoted, someone who takes a week to mow a problem over, or someone who can immediately spout off a reasonable sounding sketch of an answer that may or may not work? These cultural norms may sound inconsequential in the grand scheme of things. After all, mental speed does matter when we're trying to make time-sensitive decisions, but elevating the importance of speed so it's central to our notion of what intelligence is, reducing the wildly multifaceted nature of genius to being a fast learner or quick to find answers, it seems that's really missing something critical. Little Hanako may not be the speediest cabbage picker around, and if I were watching her struggle, I might step in to help. But it turns out if you give kids a little time to work the problem, they can astound you with their brilliance. Maybe there's a lesson in that. I'm still trying to figure it out. Can you think of a way that mental speed is privileged over other essential qualities of intelligence, things like insight or perceptiveness? Are you going to make the fry face the next time you have to take a timed test? Please leave a comment below and let me know what you think. Thank you very much for watching. Don't forget to subscribe, blog, share, and don't stop dunking.