The speed of human thought lags far behind your internet connection: Study

In our digital age, few things are more irritating than a slow internet connection. Your web browser starts to lag. On video calls, the faces of your friends turn to frozen masks. When the flow of information dries up, it can feel as if we are cut off from the world.

Engineers measure this flow in bits per second. Streaming a high-definition video takes about 5 million bps. The download rate in a typical American home is about 262 million bps.

Now researchers have estimated the speed of information flow in the human brain: just 10 bps. They titled their study, published this month in the journal Neuron, The unbearable slowness of being.

“It’s a bit of a counterweight to the endless hyperbole about how incredibly complex and powerful the human brain is,” said Markus Meister, a neuroscientist at the California Institute of Technology and an author of the study. “If you actually try to put numbers to it, we are incredibly slow.”

Meister got the idea for the study while teaching an introductory neuroscience class. He wanted to give his students some basic numbers about the brain. But no one had pinned down the rate at which information flows through the nervous system.

Meister realized that he could estimate that flow by looking at how quickly people carry out certain tasks. To type, for example, we look at a word, recognize each letter and then sort out the sequence of keys to press. As we type, information flows into our eyes, through our brains and into the muscles of our fingers. The higher the flow rate, the faster we can type.

In 2018, a team of researchers in Finland analyzed 136 million keystrokes made by 168,000 volunteers. They found that, on average, people typed 51 words a minute. A small fraction typed 120 words a minute or more. Meister and his graduate student, Jieyu Zheng, used a branch of mathematics known as information theory to estimate the flow of information required to type. At 120 words a minute, the flow is only 10 bits a second.

“I was thinking, of course there must be faster behaviors,” Zheng recalled. She suspected that championship video game players might have a higher information flow when they are competing. “You can look at them on YouTube, and their fingers are so fast that they’re just blurred on the videos.”

Though gamers move their fingers quickly, they have fewer keys to choose from than a typist does. And so, when Zheng took a close look at the performance of gamers, she ended up with the same estimate for their rate of information: 10 bits per second.

Perhaps, the researchers thought, our bodies’ physical limitations create an information bottleneck. To test that possibility, they analyzed mental feats that don’t depend on fast muscles.

One of these feats is known as blind speedcubing, in which a player looks at a Rubik’s cube, puts on a blindfold and solves it. At a 2023 competition, American speedcuber Tommy Cherry needed just 5.5 seconds to inspect his cube, which he then solved in 7.5 seconds. Zheng and Meister calculated Cherry’s information rate during his inspection: just 11.8 bps.

Even people with extraordinary visual recall have a relatively low information flow. In a memory sport called the 5 Minute Binary, players try to memorize a long string of 1s and 0s. They get five minutes to look over pages with thousands of numbers and then, after a 15-minute break, try to recall as much of the sequence as they can.

The world record for this game was set in 2019 by Mongolian memory champion Munkhshur Narmandakh, who recited 1,467 numbers. Meister and Zheng estimated that she did this with an information flow of just 4.9 bps.

The speed of human thought is dwarfed by the flood of information that assaults our senses. Meister and Zheng estimated that the millions of photoreceptor cells in a single eye can transmit 1.6 billion bps. In other words, we sift about one bit out of every 100 million we receive.

“Psychological science has not acknowledged this big conflict,” Meister said. More researchers should ask why we toss out so much information and get by on so little, he said.

Britton Sauerbrei, a neuroscientist at Case Western Reserve University who was not involved in the new study, questioned whether Meister and Zheng had fully captured the flow of information in our nervous system. They left out the unconscious signals that our bodies use to stand, walk or recover from a trip. If those were included, “you’re going to end up with a vastly higher bit rate,” he said.

But when it comes to conscious tasks and memories, Sauerbrei said, he was convinced that very little information flows through the brain. “I think their argument is pretty airtight,” he said.

Martin Wiener, a neuroscientist at George Mason University, said that the new study should prompt researchers to compare our information flow with that of other animals.

“A lot of people haven’t paid attention to other species,” Wiener said. It’s possible that some animals will get by on even slower rates of information. Or perhaps flying insects that make split-second changes to their flight patterns enjoy torrents of information flowing through their brains that we mere humans can only imagine.