How Slow Are Humans Compared to Computers? Comparing Temporal Resolution

I’ve been hearing people use different analogies to get a sense of how slow humans are from the perspective of a hypothetical silicon-based agentic being.

Here are some popular ones:

• Humans are like plants to an AI
• Humans are like glaciers to an AI
• Humans are like rocks to an AI

Well, plants are a lot faster than rocks. Let’s try and see if we can get a better sense of how fast computers are relative to humans using this type of analogy.

First, physical speed on a large scale (walking, sliding, or eroding perhaps) is intuitively different from computational speed. It’s hard to measure the computational speed of glaciers as they don’t compute anything by the common understanding of the word compute. However, we’re not asking how fast the robot arms move which are controlled by our hypothetic agent. We just want to know how fast it processes information.

How do we measure thinking speed? There is more than one intuitive way to do this. We might try to measure something to do with awareness - temporal resolution of experience. Perhaps we should consider the duration of the shortest perceivable external stimulus.

Alternatively, we could consider physical limitations of neurons. How fast is an individual neuron? That’s going to be an upper bound on speed. The speed at which information can travel through space is less relevant, since some physical systems are smaller than others and therefore do not require the same information transfer speeds to get the same performance.

Here are some numbers I found:

Humans

• Action Potential Timing: Neurons can fire action potentials with millisecond precision. The absolute refractory period (the minimum time between two spikes) is typically 1–2 ms.
• Synaptic Transmission: Slower synapses (e.g., NMDA receptors) take tens to hundreds of milliseconds.
• Auditory gap detection: Neurons in the auditory brainstem can sometimes detect gaps in sound as short as 2.22 ms.
• Visual stimulus detection: We can’t see things which appear for less than 10 ms.

So if we’re being really generous to humans, we could say our highest temporal resolution is about 1 frame per millisecond, and we certainly have a conscious experience much slower than this.

Computers

I think for this thought experiment we want to assume processors don’t get wildly more powerful than they are now. Let’s assume a superintelligence runs on a processor with clock speeds in the range of today’s best chips (~5 GHz). Computers can be faster than humans in other ways - massively parallel computation for example - but let’s stay simple.

$$ 5 \cdot 10^9 \frac{\text{operations}}{\text{second}} \implies 0.2 \frac{\text{ns}}{\text{operation}} \approx 10^{-10} \text{ sec per operation} $$

There are supercomputers that are much faster than this (Aurora) but this is a very reasonable estimate. Note the fastest GPUs are slower than 5 GHz but still faster than 1 GHz.

What about experiential temporal resolution? This is of course hypothetical, but we can imagine sensor speed won’t be a limiting factor for AI, as laser sensors can measure events as short as a few femtoseconds, which is so short you probably didn’t even know it was a thing. So experiential temporal resolution could very easily be in the range of nanoseconds.

Plants

In Mimosa pudica, the touch-me-not, which is one of the fastest plants, a nice high theoretical upper bound for individual cell temporal resolution is 1000 events per second (1 ms per event). The actual reaction time is more like 1 whole second. Calcium oscillations up to 100 Hz in specific plant responses is more realistic than 1000 events per second.

I don’t know that plants have experiential temporal resolution in the way humans do. If they do, it’s probably slower than human experience, proportionally.

So we’re estimating plants are at least 10 times slower than humans.

Glaciers

Glaciers don’t really transmit information internally as far as I know. The analogy which was originally made between humans and glaciers was probably referencing their physical speed.

Really fast glaciers can move about 0.116 millimeters per second. Humans can easily move at 2 meters per second. So the ratio here (which to be clear is about physical movement, not information processing) is 1:17,000.

Rocks

Rocks can actually move really quickly. The fastest rock ever recorded was the Chelyabinsk meteor, which entered Earth’s atmosphere in 2013 at speeds of about 19.8 kilometers per second. I’d say humans are slower than rocks in the limit, in practice. Of course, movement is all relative, anyway.

Rocks cannot compute, but their composite atoms and subatomic particles react to each other pretty quickly. The same goes for plants and humans and computers. I think the analogy here is hard to quantify.

Conclusion

The temporal resolution of computers is approximately $10^6$ times faster than that of humans. Plants are not that slow; maybe ten times slower than humans. Their cognition is limited by factors other than speed. Glaciers and rocks don’t really do computation and therefore it’s hard to talk about temporal resolution from their perspective, but if we compare physical human speed to that of a fast glacier then humans are just $10^4$ times faster than glaciers.

It seems we have a hard time thinking of anything which is slower than humans proportionally to the degree to which computers are faster than us. I’d suggest a slime mold as one possible candidate; a human might solve a problem in a second that a slime mold takes weeks to “compute” through its growth patterns. Two weeks is $10^6$ seconds.

In terms of physical speed, tectonic plates moves at about 5 cm/year, which is $10^9$ times slower than a human. There are certainly some glaciers which move about 60 meters in a year, which is $10^6$ times slower than a human.

So next time you sit waiting while a reasoning LLM ‘thinks’, you should remark at how amazingly slow it is compared to you, relative to temporal resolution.