What Makes Light and Color Unique in Our Perception?

[Furyan5]

Very true, but if a searchlight beam travels through dust, the beam will stand out. A small fraction of the beam is scattered, so indirectly, you know that light is passing you by.

It's not the beam of light you see, it's the dust in the path of the beam that becomes brighter. The beam itself is undetectable unless it strikes your retina. Then it becomes detectable, not visible.

 

[Furyan5]

It is the definition of "red". Go to a home-improvement store, look at the paint department, and see how many different "reds" there are.

I am a bit surprised that there aren't more quantitative aspect of this discussion. I know that the topic is centered on "seeing" light, as in visible light, using our human eyes. But why hasn't there been any attempted to actually define this through specific wavelength or frequency of that light? After all, this is one surest way of distinguishing EM radiation. You may call one color red, while another person may call it "pinkish red" or "wine red", but no one will argue if we categorize them instead by their wavelengths. It is the least ambiguous way to define any EM radiation.

Or is it because our eyes can't actually spit out these values that we are not going to consider such quantitative description? But what's wrong with using an instrument to detect such values?

Zz.

That's because color is not a direct interpretation of wavelength/frequency and amplitude. There are other physiological factors involved as well. Google the strawberry illusion. The strawberries look red but there is no "red" light. A "red" balloon looks "black" under "blue" light. There are many such examples. Colour isn't fixed by a lights particular wavelength/frequency or amplitude.

 

[David Lewis]

The beam itself is undetectable unless it strikes your retina. Then it becomes detectable, not visible.

Good point. Visibility refers to raw sensory input. Detection involves reasoning.

 

[Furyan5]

Good point. Visibility refers to raw sensory input. Detection involves reasoning.

Correct. Without the brain to interpret the data from the eyes, nothing is perceived.

 

[ZapperZ]

That's because color is not a direct interpretation of wavelength/frequency and amplitude. There are other physiological factors involved as well. Google the strawberry illusion. The strawberries look red but there is no "red" light. A "red" balloon looks "black" under "blue" light. There are many such examples. Colour isn't fixed by a lights particular wavelength/frequency or amplitude.

"Color" is a handwaving human characterization of EM radiation that human can see. "Wavelength" is a more definitive characterization of EM radiation that isn't affected by "physiological", social, cultural etc. factors. So why not deal with that?

Zz.

 

[Furyan5]

"Color" is a handwaving human characterization of EM radiation that human can see. "Wavelength" is a more definitive characterization of EM radiation that isn't affected by "physiological", social, cultural etc. factors. So why not deal with that?

Zz.

What exactly do you mean by "deal with that"? You're welcome to start a thread concerning wavelengths and what concerns you about them. In regards to this thread, they play no relevance.

 

[ZapperZ]

What exactly do you mean by "deal with that"? You're welcome to start a thread concerning wavelengths and what concerns you about them. In regards to this thread, they play no relevance.

Read the rest of Post #50 on why I find this thread puzzling and why the quantitative aspect of it has been ignored.

Zz.

 

[Furyan5]

To be honest, I don't understand that post. Unless you believe light itself has color.

 

[ZapperZ]

To be honest, I don't understand that post. Unless you believe light itself has color.

OK, one more time:

1. "Color" is a human invention. It is a sloppy and ambiguous way of characterizing EM radiation.

2. "Wavelength" and "frequency" of EM radiation are more direct, clear, and definitely less ambiguous. So why aren't you including the discussion of different types of EM radiation using such characterizations rather than just using "colors"? It is why I asked if you are only restricting yourself to using the human eye as the sole light detector.

Is this clearer now?

Zz.

 

[russ_watters]

Well, no, I mean "touch" in the sense that Furyan5 seems to be using it. We call the act of making a physical contact between an object and our fingers (for example) "touch" but at some level it is a physical interaction between the receptors in our body and the physical environment. Whether we are reacting to photons, or vibrations, or pressure, or molecules locking into receptors, at the most basic level all senses are our receptors reacting to a physical interaction with our environment. So all sensing, in that sense, is "touching" our environment, and causing some internal model or representation of the thing we touched. No representation is the thing itself, it is only an inner response to the exact same set of signals from our receptors which depend upon the touch of the external environment to enable this.

I'm sorry, but this just doesn't seem very meaningful to me. In order for things to interact (except perhaps in QM), they have to be co-located. So what? Or is that the whole point?

 

[russ_watters]

We don't actually see light, we see because of light. Our brain doesn't create a visual representation of light itself, for us to perceive. The brain interprets light into sensations such as colors and brightness. It's this we perceive. It's through colors and brightness that we perceive objects. The contrast from its surrounding colors and brightness.

Well, we "see light" in the sense that photons themselves hit photosensors and trigger a response.

 

[sophiecentaur]

Are you talking about emotional responses to colors? Or understanding what colors are and how we see them?

Everything in our minds is 'emotional' to some extent. Everything we experience is subjective. We invented Mathematics as a way of communicating in a very formal way and we have agreed on the syntax and 'meanings' it carries. But when we try to communicate any of our sensations to another individual, we are limited to our language or to real life examples (eg red is like strawberries and coke bottles - no use for someone who has seen neither).
We 'understand' (a dodgy word in most contexts and even more so in psychology) that colours can be mimicked and measured up to a point so we can sort of reverse engineer human colour vision. whether or not that involves understanding of the process is questionable. Colour is only really in our heads. Outside of our heads, we can only use a model that can predict reasonably well what colour a human will assign to a given spectral mix on a screen.

 

[Furyan5]

OK, one more time:

1. "Color" is a human invention. It is a sloppy and ambiguous way of characterizing EM radiation.

2. "Wavelength" and "frequency" of EM radiation are more direct, clear, and definitely less ambiguous. So why aren't you including the discussion of different types of EM radiation using such characterizations rather than just using "colors"? It is why I asked if you are only restricting yourself to using the human eye as the sole light detector.

Is this clearer now?

Zz.

The thread is not about whether we detect light or not. Everyone agrees that we detect certain wavelengths. The thread is about whether we perceive light or not. Is the detection of light by the eye called seeing when all other visual perception occurs in the visual cortex. Is detecting light, seeing or only a part of the process which results in seeing. Opinions seem to differ, so I'm seeking clarity, with an explanation, why people believe one or the other.

 

[sophiecentaur]

The human eye is not a spectrometer and our appreciation of the spectrum of the light we see is only based on a very crude analysis. Only three basic broadband analysis filters have been identified but our vision system makes good use of that data and context to come up with a highly data reduced measure. It's good enough for us to have survived ok and that's all that evolution needs to provide us with.
There is a lot of very sloppy terminology around - even on PF - which refers to the 'wavelength of colours'. I am always surprised that the basics of tristimulus colour vision seem to be too much for many otherwise bright people to take on board.

 

[Furyan5]

I'm sorry, but this just doesn't seem very meaningful to me. In order for things to interact (except perhaps in QM), they have to be co-located. So what? Or is that the whole point?

Answered in #64

 

[ZapperZ]

The thread is not about whether we detect light or not. Everyone agrees that we detect certain wavelengths. The thread is about whether we perceive light or not. Is the detection of light by the eye called seeing when all other visual perception occurs in the visual cortex. Is detecting light, seeing or only a part of the process which results in seeing. Opinions seem to differ, so I'm seeking clarity, with an explanation, why people believe one or the other.

This does not sound like a physics question. It is more physiological, biological.

Zz.

 

[jim mcnamara]

Thanks to everyone for participating. This thread is slowly going off-topic, so it is closed.