Researchers Measure the Speed of Human Thought in Bits

A study by the California Institute of Technology reveals that the human brain processes information at a remarkably slow rate—around 10 bits per second.

This is staggeringly slower than the data collected by our sensory systems, which process information 100 million times faster, according to New Atlas.

While often hailed as the most powerful “computer,” the brain’s computational speed is modest when compared to machines. Researchers sought to quantify the speed of human thought in bits—a standard unit for measuring data.

Defining a “Bit” of Thought

The study began by identifying what constitutes one bit of information in human terms. For example:

When writing, one bit equals one character of text. A professional typist, typing 120 words per minute (around five characters per word), processes about 10 bits per second.

For speech, the recommended speed for comprehension is 160 words per minute, equating to approximately 13 bits per second.

The researchers extended this analysis to extreme examples of human information processing:

Speed cubing: Solving a Rubik’s cube at 11.8 bits per second.
Digit memorization: Recalling numbers at 4.9 bits per second.
Professional Tetris: Executing moves at 7 bits per second.
Speed card memorization: Scanning and recalling a shuffled deck at 17.7 bits per second.

From these examples, the researchers averaged human cognitive processing speed at 10 bits per second.

The Brain vs. Sensory Systems

The study also highlighted a stark contrast between the brain’s processing speed and the capacity of our sensory systems. A single photoreceptor in the human eye transmits around 270 bits per second, scaling to 1.6 billion bits per second per eye.

This information is compressed by the optic nerve to 100 million bits per second—still far beyond the brain’s processing capacity.

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Despite this disparity, the brain filters these immense data streams to extract just 10 bits per second, which are used to perceive the world and make decisions.

Why is human thought so slow? The researchers suggest this limitation may be rooted in evolution. Early humans prioritized survival tasks like finding food or evading predators, which required only a single “train of thought” at a time. In such an environment, processing 10 bits per second was sufficient.

“Our ancestors lived in a world slow enough to make survival possible. Most of the time, even 10 bits per second exceeded the demands of their environment,” the researchers explain.

But these figures are somewhat alarming in light of future technologies. Computers, robots and artificial intelligence can process information much faster than us and will only accelerate.