You Are a Dial-Up-Mode Computer: Why Do We Live at 10 bits/s?
Paper: *The Unbearable Slowness of Being: Why do we live at 10 bits/s?* Authors: Jieyu Zheng, Markus Meister (Caltech) Journal: Neuron, 2025 DOI: 10.1016/j.neuron.2024.11.008 arXiv: 2408.10234
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Key Points
1. The Setup: Twenty Questions
The "twenty questions" game conveys ~20 bits in a few seconds, yielding ~10 bits/s of thought. That number is the seed of the entire paper.2. The Sifting Number (10⁸)
- Sensory input: ~10⁹ bits/s (eyes, ears, skin).
- Behavioral output: ~10 bits/s (typing, speaking, thinking).
- The gap is roughly 100,000,000x, a ratio the authors call the *Sifting Number* and possibly "the largest unexplained number in neuroscience."
- Professional typists (≈ 10 bits/s).
- Blindfolded speed-cubers: 65 bits memorized in 5.5 s ≈ 12 bits/s.
- Memory-sports champions: 4.9–17.7 bits/s.
- English listening ≈ 13 bits/s, reading 28–45 bits/s.
- StarCraft pros ≈ 10 bits/s, Tetris S-rank ≈ 7 bits/s.
- Choice reaction tasks ≈ 5 bits/s.
- A single cone cell: ~270 bits/s.
- A cortical neuron at a few Hz: ~10 bits/s, equal to all of human cognition.
- Optic nerve: ~100 Mbit/s (already compressed ~10x from the photoreceptors).
- The puzzle is not "slow neurons" but what 86 billion fast processors are coordinating.
- Photographic memory: World memory champions also top out near 10 bits/s; the famous 1970 Stromeyer result was never replicated.
- Rich peripheral vision: Subjective inflation; outside the fovea, only 2–3 letters are legible. Half of observers miss a person in a gorilla suit during inattentional blindness.
- Massive unconscious processing: Striped-rearing kittens need only ~2 bits of cortical reorganization, and natural-image statistics are translation-invariant, so a CNN-like scheme needs few templates, not a global processor.
- Inefficient neurons: Rejected; single-neuron precision is excellent (1 ms timing; single cortical neurons match whole-animal discrimination).
- Redundant design: Rejected; primate retina has ~1 neuron per cell-type per visual field location, with little overlap.
- Serial attention bottleneck: Partly correct, but uninformative; it does not specify the mechanism, and even chess masters evaluate moves one at a time.
- Complexity bottleneck: Pure labels ("single channel," "limited resources") are not explanations. A 2,000-neuron decision circuit or a 650,000-neuron AlexNet-like module easily fits inside 1 mm² of cortex, so the constraint cannot be raw compute.
- How does the slow inner brain drink from the sensory Hoover Dam?
- How can V1 and PFC, with similar cell counts and architecture, run such different algorithms? Perhaps PFC, like V1, contains thousands of small specialized modules rather than 2–3 latent variables.
- *"Is 10 bits/s a measurement artifact?"* Unlikely; a century of independent methods converge.
- *"Then why not parallel?"* The paper honestly admits this is the central unanswered question.
- *"Is 10 bits/s enough?"* Yes, for ancestral niches; no, for highways of machine cognition, which is why humans should vacate those niches when machines arrive.
- Zheng, J., & Meister, M. (2024). The unbearable slowness of being: Why do we live at 10 bits/s? *Neuron*, 113(2), 192–204. https://doi.org/10.1016/j.neuron.2024.11.008
- arXiv preprint: 2408.10234 [q-bio.NC]
3. Is 10 bits/s Real?
The figure converges across:4. The Hardware Is Not the Limit
5. Three Illusions Debunked
6. Five Striking Implications
1. A lifetime of learning fits on a thumb drive (<5 GB), versus ~50 TB of synaptic capacity, four orders of magnitude of redundancy. 2. Adolescents are not wrong that "reality is broken"; ancestral niches were slow, so everyday tasks feel unbearably slow. 3. Flies show the same paradox: a tethered fly controls flight at 0.62 bits/s while its H1 neuron runs ~100x faster. 4. Elon Musk's Neuralink claim of a "bandwidth problem" may be a Musk Illusion: BCI throughput will also converge near 10 bits/s, the same as a telephone. 5. Retinal prostheses that try to inject Gbit/s streams into the optic nerve have failed; the correct path is real-time scene-to-speech translation, already practical since 2018.7. Four Candidate Explanations, None Complete
8. Outer Brain vs. Inner Brain
| | Outer Brain | Inner Brain | |---|---|---| | Connectivity | Sensory + motor | Behavior control | | Dimensions | Millions of receptors/effectors | A few bits | | Rate | Gbit/s | 10 bits/s | | Parallelism | Massive parallel | Serial | | Example | Retina, V1 | Prefrontal cortex |The unsolved problems:
9. Feynman's Likely Objections
10. One-Sentence Summary
The sensory apparatus handles ~10⁹ bits/s, but a lifetime of thought, speech, and action outputs at ~10 bits/s; 86 billion neurons and 10¹⁴ synapses, the most complex known object in the universe, produce the throughput of a 1980s modem, and we do not know why.---