In a previous post, I gave a case for practicing improvisation slowly, in a very particular way.

Here’s a different way of understanding the need for slow practicing which I’ve seen play out unmistakably in my own practice and in my work with students. To make it clear, let’s first take an aside into the world of… video game design.

Video Games

In the early days of video games, each game was made for a specific computer. Whether a personal computer like the Apple IIe, a video game platform like the Atari 2600, or a dedicated arcade game like Lunar Lander, the designer knew exactly the hardware that the code would be running on. So the trick was to make sure that at each tick of the computer’s clock the imaginary world of the video game advanced just enough to make the game proceed at just the right speed.

This caused problems when a video game was written for a computer and then a faster version of the computer was released. The video game still worked fine, but the faster speed of the computer meant that everything in the world of the video game moved faster too. (That’s why some old computers had a TURBO button. It allowed the computer to run faster in general, but for video games and other programs where a fixed speed was important, you could turn off the computer’s turbo feature and it would run slower, at the speed originally intended by the game’s coder.)

Modern video games work differently. As a game is running, each time it gets around to advancing the imaginary world inside the game, it checks the clock of the computer it’s running on… and advances the game world just enough to keep up with how much the real world clock has advanced. So a fast computer will update its game world more often that a slow computer, and by littler amounts, in accordance with the smaller amount of time the player has been waiting since the last refresh. And so the game world will run at the right speed regardless of the speed of the computer.

Now back to music…

Think of your body, for a moment, as a computer. When you use your body to play a musical passage on an instrument, you coordinate the speed of your actions with your internal sense of time that serves as your metronome. If you were to simply play the notes as fast as you can, you’d be just like a video game running in turbo mode, with time dictated by the speed of your “hardware” rather than the piece of music.

Problem is, sometimes a passage comes along where you can barely play it up to speed. If you’re not careful, you can learn to play a section not by consciously keeping in sync with the piece’s tempo but rather by practicing until your ability is just advanced enough to match the tempo. At which point you stop practicing and rely on your fastest speed to perform the passage, since it is right at the desired tempo.

That’s bad.

It’s bad because you won’t be able to play it at a different tempo. You may perform the rest of the piece correctly, but you’ll rush through the section you’ve learned at “max speed.” Or you’ll drag there if the new tempo is faster than you practiced it.

It’s also bad because you’ll drag if you’re tired and sluggish one day, or if it’s cold and your hands are moving slowly… and you’ll rush if your ability increases, or you’re having a particularly energetic day.

This is a mistake that’s more common among beginning and intermediate students. Experienced players may know intuitively when they’re calibrating to their physical limitations rather than the tempo itself, because it feels out of control when they play. Others will not notice the difference.

One way for anyone to know for sure whether this is going on is to purposely slow down the tempo. At a slower speed, passages you have learned based on your sense of time will sound fine. But passages you have accidentally tethered to your physical ability will come out rushed. Or worse: you may be completely flummoxed trying to play them, and find that you no longer even know how they’re supposed to go! That’s an indication that you never really knew how they were supposed to go… or that your execution was so divorced from any idea you had of how it was supposed to go that, when you don’t have your muscular limitations to set the tempo, you’re completely lost.

When you practice slow, you can be sure that you’re not basing your execution on muscular constraints. As a result, your playing will be more precise and more adaptive to changing circumstances.

More about slow practice

A final word: there are still other compelling cases to be made for practicing slowly. One is the 1978 research result of Kerr & Booth, which indicates that for the most robust learning to occur we should practice both slower and faster than our target tempo. I won’t go into that here, but if you want a good summary of it, check out Chapter 8 of the excellent book Make It Stick: The Science of Successful Learning by Brown, Roedinger and McDaniel.