Researchers at the California Institute of Technology say that the speed of human thought reaches just 10 bits per second — and that’s incredibly slow. Meanwhile, the sensory systems of the human body perform significantly better, collecting data about our environment at a rate of a billion bits per second.
A bit is the basic unit of information in computing (for instance, a typical Wi-Fi connection can handle 50 million bits per second). The study, published December 17 in the journal Neuron, used a similar calculation method to determine how fast the brain works while a person reads, writes, plays video games, and so on.
“That’s an incredibly low number,” says one of the study’s authors, Markus Meister. “Every moment, we extract just 10 bits from the trillion that our senses perceive, and use them to feel the surrounding world and make decisions. This raises a paradox: what does the brain do to filter all this information?”
There are over 85 billion neurons in the human brain, a third of which are designated for high-level thinking and located in the cortex. Individual neurons are powerful information processors and can easily transmit more than 10 bits of information per second. But why don’t they do it? And why do we need so many if we think so slowly? Meister suggests these paradoxes will be addressed in future studies.
Another mystery raised by the new study: why does the brain process one thought at a time, instead of many in parallel, like our sensory systems do? For example, a chess player who anticipates a set of future moves can only explore one possible sequence at a time, not several simultaneously. The study suggests that this may be related to the way our brain evolved.
Previous analyses showed that the earliest creatures with nervous systems used their brains primarily for navigation, to move towards food and hide from predators. We still use this navigation today, but for different tasks.
“Human thinking can be seen as a form of navigating through a space of abstract concepts,” write the scientists. “Our ancestors chose an ecological niche where the world is slow enough to make survival possible. Indeed, 10 bits per second are only needed in the worst situations, and most of the time our environment changes much more slowly.”
The new quantitative assessment of the speed of human thinking might cancel out some sci-fi futuristic scenarios — such as in brain-computer interfaces being developed by companies like Elon Musk’s Neuralink, which suggest that people could communicate faster than in normal conversations. The new study suggests that our brains will communicate through neural interfaces at the same speed — 10 bits per second.