The human brain‘s ability to think and make decisions is surprisingly slow, even though its senses take in enormous amounts of information every second. Scientists have found that sensory systems process around one billion bits of data per second. But cognitive thinking, decision-making, and behavior only average about 10 bits per second. That’s a gap of 100 million times between what the brain sees and what it can actually process.
Researchers describe the brain as working in two modes. The outer brain handles fast sensory processing. The inner brain handles slower decision-making. The inner brain filters incoming data, throws out what it doesn’t need, and focuses on one action at a time. Scientists call this process “sifting.” It narrows a massive stream of sensory information down to a tiny flow that controls behavior.
Brain scans using fMRI technology have helped identify where this slowdown happens. A network including the inferior frontal junction, superior medial frontal cortex, and bilateral insula appears to act as a unified bottleneck. These regions activate during both response selection and perceptual tasks.
When people try to do two things at once, these areas show delays that match real-world slowdowns in behavior. Studies on dual-task performance back this up. When two tasks happen within 200 to 500 milliseconds of each other, people experience what scientists call the attentional blink. Reaction times slow down noticeably. The brain simply can’t run multiple task sets at the same time.
Even impressive skills show this limit. Speedcubers who solve Rubik’s Cubes while blindfolded process information at under 12 bits per second. Reading, problem-solving, and other complex tasks all hover near 10 bits per second. Guinness World Records and cross-disciplinary research confirm this uniform low throughput across many different human behaviors.
Individual neurons can actually transmit at 10 bits per second or faster. Yet overall behavior stays slow. One-third of the brain’s 85 billion neurons are dedicated to high-level thinking. Selective attention identifies relevant information while filtering out distractions, helping the brain manage its limited cognitive throughput more efficiently. Scientists still don’t fully understand what drives these inner brain limitations, leaving a major gap in knowledge about how the brain works.
Working memory serves as the brain’s essential space for conscious, active thought, temporarily holding and manipulating information needed for tasks like problem-solving and decision-making, yet it operates under its own severe capacity and duration restrictions that compound the bottleneck effect.
References
- https://pmc.ncbi.nlm.nih.gov/articles/PMC3158154/
- https://nesslabs.com/cognitive-bottlenecks
- https://globalpost.com/stories/human-brain-data-processing-far-slower-than-thought/
- https://www.mindspadenver.com/blogs/the-slowness-of-human-behavior-unlocking-the-brains-speed-limits
- https://magazine.caltech.edu/post/speed-of-thought-meister-zheng
- https://arxiv.org/html/2408.10234v2
- https://www.youtube.com/watch?v=EnltgiUR3eo
- https://www.smithsonianmag.com/smart-news/the-speed-of-human-thought-is-far-slower-than-the-average-wi-fi-study-suggests-180985752/
