• Although the human brain is capable of sifting through a billion bits of information per second, scientists recently found that the top speed of human thought only comes in at roughly 10 bits per second.
• To discover this limit, scientists applied techniques found in the field of information theory to a vast array of human behaviors, including reading, writing, and solving a Rubik’s Cube.
• It’s possible that a human’s speed of thought is as slow as it is because the brain evolved to chart a simple path toward food or away from danger, and millions of years later, it’s constantly working to chart paths through seas of abstract thought.

The human brain has many advantages over even the most advanced AI—creative thinking, ethical judgements, and intuition, just to name a few. But when it comes to information processing speed, humans lag considerably behind their new technological competitors.

In a new study published in the journal Neuron, scientists from Caltech detailed how they calculated the speed of human thought. Yep, you read that right (but how fast did you read it?). This isn’t the speed at which synaptic impulses travel from the sensory neurons to the brain (that’s roughly 120 meters per second in case you’re curious). Instead, it’s how many bits of information the brain processes in thoughts per second.

Considering the sophistication of the human brain, that number is surprisingly low: only 10 bits per second. By comparison, a simple Wi-Fi connection can process 50 million bits per second. So, with some 85 billion neurons in the brain capable of gathering data about our environment at a rate of one billion bits per second, why is the speed of thought so comparatively slow?

To arrive at this number, Caltech professor Markus Meister and Caltech Ph.D. student Jieyu Zheng applied concepts found in the field of information theory to a vast array of human behaviors, including reading, writing, playing video games, and even solving a Rubik’s Cube. The end result was a clear 10 bits/s.

“This is an extremely low number,” Meister said in a press statement. “Every moment, we are extracting just 10 bits from the trillion that our senses are taking in and using those 10 to perceive the world around us and make decisions. This raises a paradox: What is the brain doing to filter all of this information?”

Another question that arises when considering this mental speed limit is why the brain chooses to focus on just one thought at a t