Ten bits a second

There is a number at the bottom of every interface you have ever used. Zheng and Meister, at Caltech, published it in Neuron: the human sensory system takes in on the order of a billion bits per second, while human behavior puts back out about ten. Ten bits, against a billion. Everything you have ever said, written, typed, or clicked rode through that pinhole.

The ratio is not an accident of engineering. Perception is massively parallel: a hundred million photoreceptors fire at once, and the cortex happily processes the whole scene. Action is serial. You can articulate one word at a time, and the motor system enforces the queue. Somewhere between the rich world going in and the thin stream coming out, the bandwidth collapses by eight orders of magnitude. The brain thinks in a flood and speaks in a drip.

The brain thinks in a flood and speaks in a drip.

What the number rules out

Every conventional interface inherits the limit. A keyboard at forty words a minute, a microphone at a hundred and fifty, a touchscreen tapped by two thumbs: all of them sit downstream of the same serial channel. Making the computer faster has never helped; the bottleneck is on the human side of the cable. If you want more throughput, you have to move the tap upstream of the motor system, closer to where the intention forms.

Moving the tap upstream

Invasive work proved it can be done. Electrode arrays reading the speech cortex have produced full sentences in patients who could not speak, and ECoG work has decoded words with useful accuracy. Surgery, though, will never scale to the people who merely want a faster interface, let alone to everyone. The non-invasive route is fainter per reading and makes up the difference with scale: many brains, many sessions, many devices, one model, until whose head the signal came from stops mattering.

That is the whole arithmetic behind this company. The input side of computing has been parked at ten bits a second for the entire history of the industry. The sensory side runs a billion. We are building toward the day the second number is the one your software sees.