Kevin Warwick had a sonar sense implanted and could sense whether an object was close or far. Evidence is accumulating that our brains can make sense of "foreign" information like sonar (consider the vOICe).

It can be assumed/hoped that artificial eyes will feed the human brain information more than the currently available spectrum (into the visual sense, not through the sense of warmth).

Infrared via carotine diet

There possibly were army experiments to extend the human spectrum into the realm of infrared by maintaining a special carotine diet, but they were abandoned) when technological advances made seeing infrared easier.

Ultraviolet in aphakic patients - edited in

Some people with cataracts have their lense removed (resulting in aphakia), reportedly leading to UV vision.

The eye represents a compromise between clear focus and breadth of spectrum. What does ultraviolet look like? Prof Stark possesses UV vision because he is aphakic in one eye and, with Professor Karel Tan, has published research on the nearest visible equivalent. His conclusion is that it looks whitish blue or, for some wavelengths, a whitish violet.

Thought experiment

A thought experiment with an extended visible spectrum seems interesting to me. It touches both on the qualia debate and cognitive science. I still hope you won't vote this off-topic, because I don't think cognitive science has the answer concerning the subjective experience of the stretched spectrum.

I can think of two main possibilities.

for reference the current (most common) human visible spectrum with wavelengths as objective baseline (from Wikimedia)

human visible spectrum

1. Our current repertoire of colors is stretched.

enter image description here

2. We see new colors.

enter image description here

Has this been debated in the literature? What is being proposed? Are (1) and (2) actually the same (more acuity = more colors)?

I think there is no expectation implicit in language (infrared and ultraviolet), but still when people want to demonstrate heat vision they often use red color and, um, well I don't know any movies about superheros with bee vision.

  • 1
    @Joe I changed the wording, so that it's clear that I don't want a speculative answer, but arguments on a thought experiment. If you're actually opposed to allowing Mary's room and other thought experiments into p.se, I think you ought to reconsider and I hope others won't support you. We didn't even agree on the FAQ and you're citing the generic stackexchange FAQ.
    – Ruben
    Commented Jun 11, 2011 at 19:35
  • 1
    thank you for reformulating. I'm definitely not opposed to philosophical thought experiments, I'm just a little hesitant about open-ended "what if...?" question patterns even here. I think the new question sentence is much stronger (and a fairer representation of your interesting question.)
    – Joseph Weissman
    Commented Jun 11, 2011 at 19:43
  • 1
    @Joe I would ask about specific views on this question, but I suspect this is a newer thought experiment and I'm not versed well enough in academic philosophy to know who might have argued for either option.
    – Ruben
    Commented Jun 11, 2011 at 19:52
  • 2
    have added the 'metaphysics' and 'philosophy-of-technology' tags.
    – Joseph Weissman
    Commented Jun 11, 2011 at 23:11

3 Answers 3


If we put the thought-experiment in the context of evolution, both cases are possible. Different species of animals have different perceptual color spaces, some more than three dimensions. One can imagine the human eye evolving new photoreceptors sensitive to infrared and ultraviolet (and it is possible that something similar to this has already happened) giving case 2. One can also imagine the peak sensitivity of the red and blue cones evolving outward to the edge of the spectrum continuously, giving case 1. Case 2 can also be imagined to be happening continuously with an increase in the quantity of the new photoreceptors over many generations.

It may be worth indicating that purple is an extra-spectral color. Grapheme-color syntesthesia can also be seen as an instance of enhanced color vision. To answer the question about the mapping, the CIE L*a*b* color space is perceptually-uniform, which means that indistinguishable colors are separated by the same Euclidean distance: this isn't exactly true for all persons but experiments demonstrate that it works on average.

Another thought-experiment: what color is Betelgeuse? We see it as redder than our own sun. If there are people living around Betelgeuse, what color will they see it as? Should we translate the alien word as "white", because it means "all colors which can be seen by the light of the sun"?

  • So, just to clarify, for the mapping function, you imply that there is basically a possible array of subjective states (colors) far larger and far finer than the one most of us experience. Were we to become able see other wavelengths or finer differences between them, we would simply gain corresponding access to the subjective states? But language apparently affects which parts of the spectrum we call a basic color. Also, coming from an evolutionary perspective: We wanted to find fruits etc. What use have we for infrared? Maybe it won't make sense at all.
    – Ruben
    Commented Jun 13, 2011 at 11:43
  • 1
    I think that is a fair summary. I would add that color perception is determined by both internal and external factors and for that reason the variety is limited only by what you can imagine. Commented Jun 13, 2011 at 22:18
  • But I can't imagine new colors :-) And if you can, I'm jealous ;-)
    – Ruben
    Commented Jun 13, 2011 at 22:25
  • 1
    You can try the staring experiment at en.wikipedia.org/wiki/Impossible_color. Unfortunately it doesn't work for me. Commented Jun 16, 2011 at 6:24
  • For me neither, but maybe I can find some stereoscopes in the university basement […and you never heard from me again ;-)].
    – Ruben
    Commented Jun 16, 2011 at 9:33

I'm not sure about literature around the specific thought experiment, however Representative Realism and Idealism might be something of interest.

John Locke (not the one from Lost) is one of the most famous authors around the topic, who believed all perception is an inner representation, and objects have primary and secondary qualities; primary being the shape and colour and the secondary being touch, smell. So how you perceive something is not based on the external stimulus, but how you've formed the object in your mind previously.

In the case of colours, our brain has evolved to map our mental images based on the colour range we can see. If we could see ultra-violet like bees then would we form a different mental model of the world?

Wikipedia has a more elegant explanation here.


You overlook that human color experience is an overlay of the input of three color receptors. To answer the question about seeing new colors, it would be useful to state the way the new colors are perceived.

We do not see pure spectral colors in everyday life but mixtures. Since we only have three receptors, many mixtures are regarded as the same color, but "same" is slightly different for everyone.

Birds and some humans have four color receptors (by a doubled gene coding for color receptors), they can differentiate colors that seem the "same" for humans.

So, I can say with confidence that the spectrum will be neither stretched nor linearly added to, as in your pictures.

See http://en.wikipedia.org/wiki/Tetrachromacy

  • 1
    I didn't know about tetrachromatic humans, thank you. I deliberately overlooked the technicalities of our vision system (there are many more worth mentioning in a cognitive science Q&A), because I wonder about how the brain subjectively "makes sense" of it and as I pointed out with the link to Warwick, this may be quite independent of how the information is channelled to the brain.
    – Ruben
    Commented Jun 12, 2011 at 13:36
  • Also, I don't know how you can be confident in dismissing (1) and (2) when your source says "A variety of final image processing takes place in the brain. It is not known how the various areas of the brain would respond if presented with a new color channel. [...] a true human tetrachromat would have another type of cone, and its 100 shades theoretically would allow them to see 100 million different colors." I think the information in the article (more ability to discriminate) is in line with the (1) stretched option, the second part sounds like (2) extension to me (I never said linearly?)
    – Ruben
    Commented Jun 12, 2011 at 13:39
  • @Ruben with "linearly" I refer to the color line of your spectrum that is stretched, not to properties of the stretching function. This is already not in line with three color receptors.
    – Phira
    Commented Jun 12, 2011 at 19:36
  • Okay, my 1-minute-mock-up definitely does not do trichromatic vision justice. It also ignores the opponent-process ganglion cells, our love of contrast, etc. This is deliberate.
    – Ruben
    Commented Jun 13, 2011 at 12:10

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .