Researchers at the California Institute of Technology have determined the speed of human thought: 10 bits per second. However, our body’s sensory systems collect data about the environment at a billion bits per second, which is 100 million times faster than our thought processes.
The new research opens up a wealth of new avenues for neuroscientists to study, including: Why can we only think about one thing at a time, while our sensory systems process thousands of bits of input simultaneously?
The research was conducted in the lab of Markus Meister, the Anna P. and Benjamin F. Biagini Professor of Biological Sciences, and under the supervision of graduate student Jieyu Zheng.
A bit is the basic unit of information in computing. For example, a typical Wi-Fi connection can process 50 million bits per second. In the new study, Zheng applied methods from the field of information theory to a vast body of scientific literature on human behavior such as reading and writing, video games, and solving Rubik’s cubes, and calculated that humans think at 10 bits per second.
“This is an extremely low number,” says Meister. “Every moment, we extract just 10 bits out of the trillion bits our senses perceive, and we use those 10 bits to perceive the world around us and make decisions. The paradoxical question is: What does the brain do to filter all that information?”
The brain has more than 85 billion neurons, a third of which are dedicated to high-level thinking and are located in the cerebral cortex. Individual neurons are powerful information processors and can easily transmit more than 10 bits of information per second. But why don’t they? And why do we have so many of them if we think so slowly? Given the discovery of this “speed limit” in the brain, Meister believes that neuroscience should take these paradoxes into account in future research.
Another mystery raised by the new study: why does the brain process one thought at a time, rather than many in parallel, as our sensory systems do? For example, a chess player imagining a set of future moves can only explore one possible sequence at a time, rather than several at once. The authors of the study suggest that this may be due to the way our brains evolved.
Research shows that the earliest creatures with nervous systems used their brains primarily for navigation, to navigate toward food and avoid predators. If our brains evolved from these simple systems to follow paths, it makes sense that we can only follow one “path” of thought at a time. “Human thought can be viewed as a form of navigation through abstract concept space,” Zheng and Meister write. The team highlights the need for future research into how this limitation — one path of thought at a time — is encoded in the brain’s architecture.
