<p>On a computer, we measure colour numerically, as three values, say red, green, blue. While our eyes include detectors for red, green and blue (although these aren't exactly the same as the light emitted by a computer), it is by no means obvious that we see numerical information. All I can report myself seeing is things that are more red than other things. This about order: whether something has more or less of some property. Numbers store more information than just order. One way to establish that human vision is more numerical in nature is to see if sensible things that can be defined using numbers can be detected using eyes. For example, a rate of change. To say something is getting more or less red is purely about order. But to say something is getting more red at a certain <em>rate</em>, is substantially more. Suppose we had a gradient from RGB (0,0,0) to RGB (255,0,0), that changed colour at a linear rate, but somewhere that rate changed. For example, the red value increased by 1 every pixel, then slowed to increasing by 1 every two pixels, all of a sudden. Would humans be able to reliably detect where the change <em>in the</em> rate of change occurred, just by visual inspection?</p>
<p>(Technical notes: maybe we don't have reason to suppose that the human brain uses the same number to represent the amount of red light as a computer. But, if the human brain uses a differentiable transformation of this (which is reasonable, monotonic transformations are differentiable almost everywhere), then a sudden change in rate should still be detectable. And humans see more than just order: if I see red next to black, I know there's a sudden change. So there's a notion of continuity in what I see. That's still not as much information as is stored in numbers.)</p>

CC BY-SA 4.0
2023-05-23T06:24:13.827Z
If your Q is 'Would humans be able to reliably detect where the change in the rate of change occurred, just by visual inspection?' the answer is yes of course, because we can see color changes (think glass or metal heating up in a flame); the bigger question is in what window those changes are visible, i.e., how fast is too fast and how slow is too slow for us to perceive those changes, so there's likely a sweet spot/window. Then, even more important, is what the JND is, ands my guess is that too would have an upper an lower limit. But those are guesses. So what exactly is your question?
AliceD
CC BY-SA 4.0
2023-05-23T06:26:32.123Z
Add a bit of your own research efforts so far can help you a long way to focus and clarify your question. I think it's a valid question, but exactly what are you looking for?
AliceD
CC BY-SA 4.0
2023-05-23T07:24:07.927Z
@AliceD I'm not sure what you're saying but seeing colour changes isn't the same as seeing a change in the rate of change.
Thomas Anton
CC BY-SA 4.0
2023-05-23T08:24:33.393Z
If you argue you are able to see color changes, then you can see a changes in rate, because when it first changes unnoticeably slow, and you switch it to a noticeable rate, then you are able to see a change in rate, right? At the upper limit of things, when the change approaches the flicker fusion rate, weird things may happen.
AliceD
CC BY-SA 4.0
2023-05-24T02:14:35.387Z
Hmm, I see. Thank you for your clarification. This is only one special case of what I was asking. Where the rate goes from near zero to significantly above. It would be interesting to know if people could detect changes in rate from other baseline levels.
Thomas Anton
<perception><vision><sensation><color>
Do humans see rates of change of colour
Thomas Anton
# Do humans see rates of change of colour

(Asked by: username_0 on 2023-05-20)

On a computer, we measure colour numerically, as three values, say red, green, blue. While our eyes include detectors for red, green and blue (although these aren't exactly the same as the light emitted by a computer), it is by no means obvious that we see numerical information. All I can report myself seeing is things that are more red than other things. This about order: whether something has more or less of some property. Numbers store more information than just order. One way to establish that human vision is more numerical in nature is to see if sensible things that can be defined using numbers can be detected using eyes. For example, a rate of change. To say something is getting more or less red is purely about order. But to say something is getting more red at a certain *rate*, is substantially more. Suppose we had a gradient from RGB (0,0,0) to RGB (255,0,0), that changed colour at a linear rate, but somewhere that rate changed. For example, the red value increased by 1 every pixel, then slowed to increasing by 1 every two pixels, all of a sudden. Would humans be able to reliably detect where the change *in the* rate of change occurred, just by visual inspection?

(Technical notes: maybe we don't have reason to suppose that the human brain uses the same number to represent the amount of red light as a computer. But, if the human brain uses a differentiable transformation of this (which is reasonable, monotonic transformations are differentiable almost everywhere), then a sudden change in rate should still be detectable. And humans see more than just order: if I see red next to black, I know there's a sudden change. So there's a notion of continuity in what I see. That's still not as much information as is stored in numbers.)

**Tags:** perception, vision, sensation, color

> **Comments:**
> **username_1**: If your Q is 'Would humans be able to reliably detect where the change in the rate of change occurred, just by visual inspection?' the answer is yes of course, because we can see color changes (think glass or metal heating up in a flame); the bigger question is in what window those changes are visible, i.e., how fast is too fast and how slow is too slow for us to perceive those changes, so there's likely a sweet spot/window. Then, even more important, is what the JND is, ands my guess is that too would have an upper an lower limit. But those are guesses. So what exactly is your question?  
> **username_1**: Add a bit of your own research efforts so far can help you a long way to focus and clarify your question. I think it's a valid question, but exactly what are you looking for?  
> **username_0**: @username_1 I'm not sure what you're saying but seeing colour changes isn't the same as seeing a change in the rate of change.  
> **username_1**: If you argue you are able to see color changes, then you can see a changes in rate, because when it first changes unnoticeably slow, and you switch it to a noticeable rate, then you are able to see a change in rate, right? At the upper limit of things, when the change approaches the flicker fusion rate, weird things may happen.  
> **username_0**: Hmm, I see. Thank you for your clarification. This is only one special case of what I was asking. Where the rate goes from near zero to significantly above. It would be interesting to know if people could detect changes in rate from other baseline levels.  

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