Re: bird vision, I came across this article in the July issue of Scientific American: What Birds See:
For those interested, I’ve put up the full PDF here.
This seems to me more a linguistic issue than a sensory one. Sure, we call them all ‘green’, but I think I could probably at least acknowledge the difference between many shades of it.
Also, your analogy to music does not seem particularly apt. As far as I’m aware, the division of the spectrum of sound frequencies in Western tradition is equally as arbitrary as a given language/culture’s division of the color spectrum. I might be wrong on this one though.
No, it’s not linguistic. We can build color TVs using three phosphors, and can do color printing with three colors because we only have three degrees of freedom in our sense of color. If we had four or more, we’d never be able to get away with that – the colors as we print or broadcast them now would look wrong ion some way.
Also, with sound, I’m not talking about division into particular notes – the modern chromatic scale or the ancient harmonic scales or the Easternm pentatonic scale. I’m saying that we have much better resolution in sounds than in colors (and I never said it was infinite – any physical receiver is going to have some limiting resolution, determined by its construction). we have more degrees of freedom in our sense of sound than in color. Although we can mix different proportions of spectral compositions together to get the same color as far as our eyes can tell, we can’t construct sounds that seem to be the same by playing different chords. And this is as true f you’re a modern American, an ancient Greek, or a Medieval Chinese.
No, it’s not about different colours being called the same name, it’s about the same perceptual colour having different spectrums. For example, imagine you were able to set up a computer monitor to perfectly replicate a scene as in a trasparent laptop screen setup. Pointing a spectrograph at a point on the laptop would yield 3 sharp peaks at red, green and blue and a low level everywhere else due to ambient light. Pointing the spectrograph to the point behind the laptop screen which is the exact same colour and you would get a smooth curve with no peaks. Yet both of these appear the same to the human eye.
Another sense that humans are missing is I guess what would be called “3dness”. We can simulate a crude 3d perception of the word through parralax vision but it’s not true 3d. A true 3d sense would be able to distinguish a hollow sphere from a solid one. However, for such a sense to exist, the sensorary organ would probably have to reside in the 4th dimension which doesn’t seem all that practical or even possible.
As has been already pointed out, the issue is not linguistic. The different “colors” that can be perceived depends on the number and sensitivity of different color receptors an animal has.
To give a simplistic and somewhat artificial example, we perceive the combination blue + yellow as green. A dog, with only two kinds of cone cells, may not be able to distinguish green from other colors that we can tell apart with our three kinds of cone cells. One the other hand, a bird, with four kinds of cone cells, will perceive UV + blue to be a color as distinct from blue as blue and green are to us, and one that we can no more understand than a dog can know what “green” is.
As the Scientific American article linked to above mentions, birds and other animals also have oil droplets in the eye that help to fine-tune the response of each type of cone cell, giving them an even greater ability to distinguish shades of color.
Well, we certainly don’t have smission. 
Extra eyes? I’m guessing animals like spiders have very very good depth perception.
That’s precisely what I was thinking. You could improve the parallax if you had more separations available, or more planes of parallax (we’re restricted to one plane, with two eyes). Like Spiders. Or Dr. Jumba Jookiba:
There’s a lot of work done in spectroscopic imaging instruments, of various designs. It’s easy enough to get one axis of spatial information and one of spectral information, of course. Then, you can use multiple slits, or scan your slit across an image, to get the other dimension. Alternately, you can use a standard imaging system, but with a large number of filters: This would be analogous to increasing the number of types of cones in our eyes. Or you can combine spatial and spectral information in various ways (interestingly, the deconvolution for some of these methods is very similar to the analysis the brain has to do to convert two 2-d images into a single 3-d image). Or you could attempt to construct a detector which inherently measures the spectrum: For instance, you might have a thick receptor, into which different frequencies penetrate different distances, and the 3-d information of where a photon were detected would then give you full spectral imaging.
As for use, it would enable the organism to precisely distinguish between different chemicals by sight, which might be useful for identifying foods with various toxins or essential nutrients.
I remember a science fiction short story I read once about people from another dimension - they were humans, just living in a sort of alternate reality - who had developed all of their geometry based on non-Euclidean concepts. A scientist in this alternate-reality was attempting to time travel, and as a test he sent some of his child’s simple toys in a box into the void. The toys came to our universe, where a boy discovered them and tried to play with them, only to realize that they were totally illogical because his Euclidean-conditioned mind couldn’t figure them out. IIRC, one of the toys was an anatomically correct doll that had all the features of normal humans, plus some sort of “new” system that pervaded throughout the body.
A very very hard to follow summary, but it was called something along the lines of “Mimsy Were the Borogroves” or something.
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But if we can hear their voice and smell their sweat, are they not broadcasting particles? Could it be that fear causes our bodies to emit particles that we have no means to detect?