Somebody has probably told you which half of your brain you use.
It is one of the most repeated ideas about how people think: logical, orderly, word-loving people run on the left side, and creative, intuitive, picture-loving people run on the right. Schools sort children by it. Job ads use it. There are quizzes.
The strange part is that this idea has a real ancestor, and the ancestor won a Nobel Prize. In 1981, Roger Sperry was honored for work on people whose brains had been surgically cut in half — the thick bundle joining the two sides was severed, as a last resort, to stop epileptic seizures nothing else could stop. With the connection gone, Sperry could give one half of a brain a task and the other half would not know about it.
So the finding was true, and it was about a very small number of people whose brains had been divided by a surgeon. What happened next was that it escaped the operating theater and became a personality test.
What the scanner found
In 2013 a team at the University of Utah went looking for the two types directly. They analyzed resting brain scans from 1,011 people between the ages of 7 and 29, and measured, for every pair of thousands of little regions, whether a person’s activity leaned to one side.
Lopsidedness itself is real. Language does lean left in most people. Attention to space leans right. That part has never been in doubt.
What they did not find was people. Nobody’s brain was globally tilted to the left, and nobody’s was globally tilted to the right. The lopsidedness is by job, not by person, and everybody has the whole set.
There is a good physical reason for that, and you can put a number on it.
Do that arithmetic yourself, because it is the whole argument in one line. Two hundred million seconds is about 3.3 million minutes, which is about 55,000 hours, which is about 2,300 days — a little over six years of counting without sleeping. That is the cable between the two halves you were told to pick between.
A brain is not two specialists sharing an office. It is one thing with an enormous amount of traffic in the middle.
So why does drawing help?
Here is where the myth has been doing real damage, because it gives the wrong reason for something that genuinely works.
If you believe in right-brained people, art in a science class is a treat for one kind of learner. If you look at what actually happens when a person draws something, it is not a treat and it is not for one kind of person. It is a different way of putting information in.
In 2016, three researchers at the University of Waterloo ran seven experiments on this. The setup is simple enough to picture. Participants got a list of ordinary words — apple, balloon, kite — and for each word they either wrote it out or made a quick drawing of it. Later they were asked to recall as many as they could.
People remembered more than twice as many of the words they had drawn.
Two details make this more useful than it first sounds.
The first is that skill was irrelevant. The researchers looked at whether better drawings were remembered better, and they were not. You are not being asked to make art here; you are being asked to make a mark that means something.
The second is speed. The main experiments gave people 40 seconds per word. Then the researchers cut it to four seconds — barely enough for a circle and a stem — and the advantage was still there.
They tested the obvious explanations and knocked them down one by one. It is not simply that drawing makes you think harder about the word. It is not simply that you pictured it in your head. It is not simply that pictures beat words. Their proposal is that drawing is the only one of these that pulls all three together at once: what the thing means, what it looks like, and what your hand did. One memory, filed in three places, and any of the three can fetch it back.
What a drawing makes you decide
There is a second thing going on, and it is the one we care about most in a lesson.
Writing a sentence lets you stay vague. Drawing a picture does not.
Write the Moon has phases and you are finished, and you can write it perfectly while understanding nothing. Now draw one. Immediately you have to answer a question the sentence never asked you: which side is lit? And you cannot answer that without deciding where the Sun is standing. The moment your pencil picks a side, you have committed to a claim about a thing that is not even in the picture.
This is why the drawing turns up in the middle of the science in our lessons rather than at the end as a reward. In Borrowed Light, the bright edge you pick is an argument about where the Sun is. In Feathers & Scales, drawing a feather beside a fish scale forces you to say what is genuinely alike about them and what only looks alike — which is the entire difficulty of that piece of biology. In Story Poles, you cannot design one without deciding what balance means, in a body and in a story, and those two answers have to be the same answer.
It works the same way outside the hard sciences. A timeline you draw has to have distances on it. A map of who traded with whom has to have arrows that point somewhere. Vagueness survives in a paragraph and dies on a page you have to draw.
Where the evidence runs out
Now the honest part, because this is the point where writing about learning usually starts overselling.
Everything measured above was measured on word lists in a laboratory, remembered minutes later. That is a real, repeated, carefully controlled result, and it is a much smaller result than “art makes you understand complicated systems and remember them for years.”
That larger claim is the one we believe, and it is the one we have the least proof of. Nobody has run a seven-experiment study on whether painting an aurora makes a person understand the magnetosphere in March. The bridge from drawing a picture of an apple helps you recall the word apple to drawing a system helps you understand the system is a bridge built out of reasoning, classroom experience and a lot of hope. It is worth saying that plainly rather than dressing the word-list study up as more than it is.
The other soft spot is smaller and more fun. That cable in the middle is quoted at 200 million fibers, and also at 300 million. Both numbers are in print. Nobody has counted them, because counting them is the six-year job above, and the honest form of the fact is a range.
Try it, in four seconds
You need paper and something to write with, and less time than it took to read this paragraph.
Take anything you are currently trying to remember — a word in another language, the parts of a cell, the order of something, a name. Do not write it down. Draw it in four seconds. Then close the notebook.
Some rules that are really permissions:
- It is allowed to be terrible. That was measured, and terrible works.
- It is not allowed to be a shape with no meaning. A box with the word inside it is writing wearing a hat.
- If the thing is invisible — a force, a decade, a reason — draw the effect of it instead. That is the hard, useful version.
Come back tomorrow and try to list what you drew, then the same number of things you only read. The gap between those two lists is the whole of this article, and you can measure it on yourself in a day.
Where this comes from
- An Evaluation of the Left-Brain vs. Right-Brain Hypothesis with Resting State Functional Connectivity MRI — Nielsen et al., PLOS ONE, 2013. The 1,011 brains.
- Researchers debunk myth of “right-brain” and “left-brain” personality traits — University of Utah Health, the same study in plain language
- The Nobel Prize in Physiology or Medicine 1981 — Roger Sperry, and what the split-brain work actually showed
- The drawing effect: evidence for reliable and robust memory benefits in free recall — Wammes, Meade & Fernandes, Quarterly Journal of Experimental Psychology, 2016
- Need to remember something? Better draw it — the Waterloo summary, including the four-second version and the finding that drawing quality did not matter
- Neuroanatomy, Corpus Callosum — StatPearls, for the fiber counts and the range they sit in
The diagrams above are original drawings made for this post, not reproductions from any of these sources.