The Speed of Human Thought: A Slow but Intriguing Mystery
Researchers at the California Institute of Technology have taken on the ambitious challenge of calculating the speed of human thought. Their findings suggest a surprisingly modest figure: about 10 bits of information per second.
To understand this, let’s break it down. Your first thought might be to compare “bits” here to the ones and zeros of computer language. While it’s true that a bit in computing has one of two binary values (0 or 1), the term in this context refers to a unit of information, sometimes called a “shannon.” Named after Claude Shannon, the father of information theory, one shannon represents the smallest unit of information required to resolve uncertainty.
Vincent Gripon, an associate professor at Télécom Bretagne, uses an example to explain the distinction between data and information: “If we ask a friend about the sex of her newborn baby, and there’s an equal chance of it being a boy or a girl, her response would convey 1 shannon of information. However, she might reply with a sentence containing many characters, each represented by multiple bits of data. So, while we receive only 1 shannon of information, we process dozens of bits in the message.”
The human brain handles an immense amount of data, particularly from sensory input. For instance, the visual cortex transmits up to 100 million bits of data per second to deeper parts of the neocortex. However, most of this data is irrelevant, containing very little useful information for our conscious awareness.
Reconciling Sensory Data and Conscious Thought
Scientists have long been fascinated by the disparity between the vast amount of sensory data our brains receive—estimated at a staggering 10⁹ bits per second—and the significantly slower rate at which conscious thought processes information.
In a recent study, researchers sought to quantify how much information human thought processes during specific tasks. One example they examined was manual text typing.
“A skilled typist can type around 120 words per minute,” the team explained. “If we estimate an average word to contain 5 characters, that translates to 10 keystrokes per second. To measure the amount of information this represents, we could count the number of keys on a keyboard and calculate the entropy of each character, but the English language has internal structures that make its characters predictable. The entropy of English is actually only about 1 bit per character.”
Typists use this redundancy to their advantage, enabling faster typing speeds. However, if tasked with typing entirely random sequences of characters, their speed would drop dramatically. Based on this predictability, researchers calculated the speed of thought during typing to be about 10 bits per second. They found similar results across a variety of tasks, from playing Tetris to solving a Rubik’s Cube or listening to spoken English.
“That’s an extremely low number,” said Markus Meister, a co-author of the study. “At any given moment, we extract only 10 bits of information from the trillions of bits our senses receive. We use this tiny amount to perceive the world and make decisions. This raises a paradox: What is the brain doing with all the other information?”
Implications and Paradoxes
While our brains process a deluge of sensory data, our conscious minds operate at a much slower pace. This discrepancy could have significant implications, particularly for the development of brain-computer interfaces. Although such technologies could potentially accelerate human brain activity, they may ultimately be constrained by the inherent limitations of cognitive processing speed.
The researchers also raise broader questions about the human nervous system. How is it that our peripheral nervous system can absorb information at rates of up to gigabits per second, yet our conscious behavior is driven by only 10 bits per second? Why such a massive gap between input and throughput?
One explanation, the team suggests, lies in evolution. “Cognition at such a low rate is sufficient for survival,” they write. “Our ancestors inhabited an ecological niche where the world moved slowly enough for this pace to be adequate. The 10 bits per second are only necessary in high-stakes situations, whereas most of the time, our environment changes much more gradually.”
An Open Door for Future Research
While this study provides an intriguing estimate of the speed of human thought, it raises more questions than it answers. The researchers emphasize that this finding is an invitation for further exploration.
“In particular, our peripheral nervous system can absorb environmental data at much higher rates—on the order of gigabits per second,” they write. “This creates a paradox: the enormous gap between the vast amounts of sensory input and the minuscule amount of information that guides human behavior. This discrepancy—approximately 100 million to one—remains largely unexplained.”
As our understanding of the human brain deepens, studies like this one highlight the mysteries of consciousness and cognition. Ultimately, they remind us of the immense complexity of our minds and
Leave a Reply