“Seeing” with the Ears. Can bats hear in colour? – with Polish translation

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Photons travel fast in straight lines, and can be focused with huge precision. This provides the opportunity to compute highly detailed, accurate information about the world. We are familiar with this, and we take it for granted that our eyes and associated brains enable us to navigate our way around obstacles at high speed, and hit a fast moving target like a tennis ball. We really notice the difference when darkness reduces us to helpless stumbling.


But there is a living to be made during the dark half of the day-night cycle, and it is now well known that bats have evolved the capacity to “see” without light, using their highly tuned ears rather than eyes (indeed the more specialised bats have all but completely lost their eyes). Echoes of high pitched sounds are not quite as good as well focused light but, with suitable processing in the brain, they enable the bat to fly at high speed between stretched wires without getting injured, and to catch insects on the wing, all in total darkness. Toothed whales have evolved the same “echolocation” skill (especially highly developed in river dolphins swimming and hunting in murky water where seeing is almost impossible) and by two separate groups of cave-dwelling birds.

I have long conjectured that the answer to the famous philosophical question, “What is it like to be a bat?” might be “Pretty much the same as to be a fast flying, visually hunting insectivorous bird such as a swallow.” I meant something rather specific by this. When visual animals such as swallows or people look at the world, we construct a simulation model in the brain, which is continuously updated by incoming data from the eyes, and hence bears enough similarity to the real world outside to allow navigation through it and pursuit of moving targets. The remarkable phenomena of visual illusions are best interpreted on the hypothesis that what we “look at” is not the real world itself but our internal model of it.

When the ancestors of bats and dolphins began to use echolocation, probably tens of millions of years ago, their brains already contained sophisticated simulation software, sensitively tailored to perform the mathematical calculations necessary for high speed manoeuvring. Rather than let that originally visual software languish idle, it would have been entirely natural to commandeer it to the service of the new skill, echolocation. All that was needed was a new “driver” module (to pursue the computer metaphor), that allowed echoes to update the simulation rather than retinal images. This is why I conjectured that bats “see” with their ears. The scene, as perceived by an echolocating bat, might look very much like what a swallow sees, because both bat and bird are deploying the same kind of simulation model, to perform the same kind of task.

I even stuck my neck out (for example in Unweaving the Rainbow) and wondered whether bats use colours (I meant the subjective sensations or qualia that we call red, blue, green etc.) as labels for different echoic textures of objects: perhaps “red” for shiny, hard surfaces like locust abdomens, “blue” for soft furry moths. “Red” and “blue”, after all, are only arbitrary labels for light of different wavelengths. There is nothing inherently “red” about 700 nanometres. Given that colour qualia were lying about in the brain and no longer needed as labels for wavelengths of light, why not press them into service again as labels, but labels of something else, namely echoic texture?

I was therefore intrigued to read the inspiring story of Daniel Kish in yesterday’s Guardian. At the age of one, he had both his eyes surgically removed to save him from an aggressive eye cancer. For as long as he can remember, he has been making clicking noises with his tongue, and using them to find his way around. It wasn’t until he was ten that a friend pointed out to him that he was doing what bats do: echolocation:

Every surface has its own acoustic signature – I can recognise a tree, for example, because the trunk produces a different echo from the leaves. The hard wood reflects the sound, whereas the leaves reflect and refract, too, scattering the sound waves. Everything around me becomes identifiable with a click. It provides me with a 3D image in my mind with depth, character and richness; it brings light into darkness. I can often find my way out of an auditorium quicker than a sighted person because I can identify the exit. If I'm in a noisy place such as a concert, I don't feel anxious – I just increase the volume and my click cuts through the noise. I'm very familiar with its sound and don't feel at all self-conscious if other people hear me.

I don't have superhuman hearing, even though I'm sometimes called Batman; I have just trained my ears to understand the echoes. Anyone could do it, sighted or blind – it's not rocket science. If you hold up a book in front of you and click, then take it away and click, you can hear a difference, just as you know you're in an empty room because it's echoey. When I was in college I wrote my thesis on echolocation, and during my research I had to consciously deconstruct how I was doing it to understand the process. I know there's a wall in front of me, I'd think, but what's tipping me off? I would set myself tasks and try to get quicker and quicker at navigating obstacle courses.

His ability is so surprising to sighted people that they annoyingly treat him as far more disabled than he is:

. . . although I have travelled around the world successfully, when I'm in an airport I feel that officials yearn to get me in a wheelchair, take away my documents and leave me feeling powerless. One friend wasn't allowed to leave the plane until "assistance" arrived, even though he held the world record for blind cycling; he was too nice to make a fuss but I would have insisted.

I have made it my life's work (http://www.worldaccessfortheblind.org) to teach blind children how to empower themselves using echolocation, which I call flashsonar. As you become more adept, you also click more subtly and naturally, like blinking, so often people around you aren't aware you're doing it and you aren't stigmatised for it.

He even taught himself to ride a bicycle:

Now I can ride along a busy street or go on a trail in the woods. I have never hit a pedestrian – touch wood – because I don't ride on the pavement. Cars are excellent echo targets, so I can easily avoid them. I won't say I've never had an accident, but every activity holds an element of risk.

Negotiating rush hour traffic isn't my dream; I am just glad I can if I want to. It's ironic – I spend all my time encouraging blind people to be active participants in society when, really, I'd love to step out of it. When my work is done, you'll find me in the mountains like an old hermit, with just my clicks for company.

We need not suppose that a person could ever become as good at echolocation as a bat. Bats have had millions of years of evolution to perfect their skills and tune up their brain software. Moreover, the clicks that bats use are ultrasonic – too high for humans to hear – and this greatly improves the accuracy of the echolocation, for reasons that physicists well understand. Engineers can make instruments that beam ultrasonic clicks, and instruments that can transpose ultrasound down to audible frequencies. I have myself donned an experimental headset, designed by L.Kay in New Zealand to be worn by blind people, and after only a few minutes of practice was able to get a rudimentary idea of my surroundings, though blindfolded.

(Referenced in http://etheses.nottingham.ac.uk/1655/1/467746.pdf)

I should love to know whether there is any truth in my conjecture that echoes make it possible to “hear colour”. Does Daniel Kish hear colour? He himself might be unable to answer the question because he lost his sight probably too young to remember what it was like. But he also tells us there are others who have the same skill as him. If any of them lost their sight when old enough to remember it, dare we hope for eye witness (ear-witness?) testimony that “seeing with the ears” really can become – after a lot of practice – the same subjective experience as seeing with the eyes? And do any of them actually “see” in colour? If they do, it seems a safe bet that bats do too. If they don’t (which I must say seems more likely) that doesn’t mean that bats don’t either: remember once again that bats have had millions of years in which to perfect their echolocation system.

Read the story of Daniel Kish here:

http://www.guardian.co.uk/lifeandstyle/2013/jul/13/experience-blindness-echolocation-daniel-kish?INTCMP=SRCH

 

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Czy nietoperze mogą słyszeć w kolorze?

Autor tekstu: Richard Dawkins

Tłumaczenie: Małgorzata Koraszewska
       

Fotony podróżują po liniach prostych i można je skupić z wielką precyzją. Daje to możliwość wykalkulowania bardzo szczegółowej, dokładnej informacji o świecie. Dobrze to znamy i traktujemy jako oczywistość, że oczy i skojarzone z nimi mózgi umożliwiają nam znajdowanie z dużą prędkością drogi wokół przeszkód oraz trafianie w poruszający się cel, taki jak piłka tenisowa. Zauważamy różnicę, kiedy ciemność redukuje nas do bezradnego potykania się. 

Podczas ciemnej połowy cyklu dzień/noc istnieje jednak możliwość zarobienia na życie i dobrze wiemy teraz, że nietoperze wyewoluowały zdolność „widzenia" bez światła, używając swoich wspaniale nastrojonych uszu zamiast oczu (w rzeczywistości bardziej wyspecjalizowane nietoperze niemal całkowicie straciły oczy). Echo dźwięków o wysokiej częstotliwości nie jest tak dobre jak skupione światło, ale z odpowiednim przetwarzaniem w mózgu umożliwia ono nietoperzowi latanie z dużą prędkością między napiętymi drutami bez zranienia się, oraz łapania w locie owadów, a wszystko to w całkowitej ciemności. Walenie zębowce wyewoluowały te samą umiejętność „echolokacji" (szczególnie wysoko rozwinięta u delfinów rzecznych, które pływają i polują w mętnej wodzie, gdzie widzenie jest niemal niemożliwe), jak również zrobiły to dwie różne grupy żyjących w jaskiniach ptaków.

Długo wyobrażałem sobie, że odpowiedzią na słynne pytanie filozoficzne „Jak to jest być nietoperzem?" może być „Całkiem podobnie do bycia szybko latającym, polującym na owady ptakiem, takim jak jaskółka". Rozumiałem przez to coś dość konkretnego. Kiedy widzące zwierzęta, takie jak jaskółki lub ludzie, patrzą na świat, tworzymy w mózgu model symulujący, który nieustannie uaktualniamy danymi, dostarczanymi nam oczy, a więc jest on wystarczająco podobny do rzeczywistego świata, by pozwolić nam na poruszanie się w nim i pogoń za ruchomymi celami. Te zdumiewające zjawiska iluzji wzrokowej najlepiej interpretować na bazie hipotezy, że to, na co „patrzymy", nie jest rzeczywistym światem, ale naszym wewnętrznym modelem świata.

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Written By: Richard Dawkins
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23 COMMENTS

    • Thanks for alerting us to the error, Peter. It’s been corrected now.
      The mods

      In reply to #1 by Peter Clemerson:

      Hello Richard,

      Your wrote
      “This is why I conjectured that bats “see” with their eyes.”

      Did you mean see with their ears?

      Peter Clemerson

  1. Coincidentally, today I was re-reading Chapter 4 of The Blind Watchmaker, where echolocation by various species is discussed at length…. 8-)

    As always, each re-reading of my full set of RD’s books embeds the knowledge more deeply into my comprehension, and my understanding expands. Science is awesome, and so much more satisfying than those mouldy old myth-books full of unsupported and contradictory assertions…. Mac.

  2. I suppose, in the case of blind people, the qualia are lying around waiting to be attached to something. The question is: if sighted people attach these qualia universally, how would the brain reorganise them for different sound textures? If the brain’s software is only capable of attaching ‘red’ to a particular frequency of light, would it be able to reassign it to the sound signature of, say, a smooth surface?

  3. It’s funny how sight is such a dominant sense organ in us that we find it hard to image mental constructs without it.

    I also wonder if Synesthesia (people who see colour when they hear music- I’ve been very sick with flu this week and notcied in my darkened room at night flashes around the corner of my vision with each throb of my headache) is a neurological overhang of this type of thing.

    Perhaps like our subconsious it’s there but overpowered by vision. This may also have some clues as to why schizophrenia sufferers can have hallucinations that can overpower vision? Clearly the brain needs to produce models for us to do something with they couldn’t overlap too much say sound and vision or they could be a distraction but perhaps the dominant sense is the one we ‘see’ do dogs ‘see’ with their noses or is it a ramped up more sensitive sensation like our smell? Dogs can’t just smell louder they probably smell in massive more detail or you’d think they’d find it impossible to sniff bums clearly they’re getting something we’re not from each other bums.

  4. I have heard of instances within Autism where the individual experiences colour distortions associated with the hearing of particular sounds. I think that this could have a degree of merit in terms of the brains ability to rewire and re-associate the qualia. In the case of autism, this is happening alongside sight. It would be interesting if there is any remit in which both sight and sound could have a symbiotic relationship or if that would just always result in confusion and distortion.

  5. The human ear detects limited band widths of sound from the modulated air waves on the tympanic membrane while the retina of the human eye is able to detect light waves in limited frequencies. The question remains, “are bats ears capable of detecting colour qualia from the modulation of air waves or, would there be other factors involved”

  6. Daniel is a brilliant person…amazing ! I wonder if he finds navigation better at night when there’s less background noise ? -
    Birds can see an ultra violet glow coming from very ripe fruit – different kinds of the same colour……But why would an animal even need colour differentiation if it has no vision…unless it had a visual memory of colour….especially if the animal is nocturnal…colour is pointless if you live your life at night !
    Wouldn’t warm/cold surface textures be detectable in monochrome at different heat intensities like a night vision camera ?

  7. Interesting hypothesis but I find it rather unlikely.

    The case of blind echo-locators will not help answer the question, as they could easily make color ‘qualia’ assignments based on memories and high-level association — ex. an object they remember as red has a certain echo, and then they associate the memory of that object with all similar echos and so have rather indirect association between the sound and the color.

    The other problem I see is that we already have ‘qualia’ for sound. Without getting into two much detail, the physical relationship between sounds and the initial sensory response is quite different from the way light triggers retinal cells. Most importantly, each ear gets a single linear wave form (which later gets broken out into many distinct frequencies as the ear does its own sort of fourier wavelet analysis). In the eye, on the other hand, we have just 3 types of color sensing cell (4 if you count the cones) — each detects a wide band of frequencies, and out perception of color depends on the combination of these responses (there is even a quirk such that violet (very high frequency) appears to us quite similar to purple (mix of red(low) and blue(high)). In the retina we have many such color sensor which are distributed spacially, and we use stereoscopic effects to determine depth (primarily). In the ear the frequency detecting fibers provide no spacial information at all, and depth is determined by the delay of the echo.

    Also, the frequencies of sound that bounce off surfaces are related to entirely different properties (hardness and shape mostly) of the surface that for frequencies of light (structure at the molecular/atomic level).

    So while I expect echolocators to construct high level models of their suroundings (surface, objects, etc.), when they model the properties of the surfaces and objects the relationship between the sensory input and the physical properties is just too different, and different properties will be perceived.

    Perhaps if there are functional mechanisms in the brain laying around for labeling colors these would be co-opted to label something else, but I’m unconvinced such structure need to exist for such specialized purpose. I rather suspect that the labels themselves are constructed at a higher level. Pre-linguistically, the association would have been with objects (and orange is an example of the color orange, say), post linguistically our language centers generate the labels due to learning the words. If specific “color label” functions do exist, they could be co-opted to label almost anything, including high-level concepts or categories, with no reason that they would label qualia of sound.

    Another thought: echo-locators still experience the world of non-echo sounds just as before, and as such already have ready-made ‘sound qualia’ to associate with the sounds of echos.

    I would suggest that “what it is like to be a bat” is pretty much exactly like what it would be like to keep your eyes shut and get around using your ears — only with much better hearing and a lifetime of experience interpreting (building model fo the world) based on what you hear.

    Another way of putting it, bats do not ‘see’ with their ears, they hear with their ears just like we do — only much better at it. Same goes for say, dogs, with sense of smell. Dogs do not in ‘see’ with their noses, however much they rely on sense of smell. They smell with their noses, just a lot better than we do, but qualitatively the same thing.

  8. I have often thought that the audio sense in animals including ourselves is very much a “seeing” device.
    I propose that understanding speech may be a visualisation of the patterns that the human throat and tongue make. I could even suggest that music is a high jacking of the human audio visualisation sense; and can therefore be thought of as the mind appreciating patterns visualised in a very analogous way to the enjoyment of seeing a dance .

  9. The idea that reflected sound waves could be affected by the color (note: color, not texture) of the reflector is extraordinary. Therefore I expected a more extraordinary article.

    Conclusion: the original question was wisely avoided. Just as well, as the answer (“No.”) was exceedingly unextraordinary!

    • The idea that reflected sound waves could be affected by the color

      Margana, Richard (nor anyone else as far as I can tell) was not suggesting the color of an object affects its sound, nor that one might detect the actual colors of objects by means of sound. That is simply absurd.

      The question is whether, in the absence of vision, the internal subjective experience of color might start to be associated with the experience of sounds. As a simplistic example, perhaps one might hear hard smooth surfaces as ‘blue’ while softer rough surfaces might be heard as ‘green’ and so forth. Note that is could just as easily be the opposite, or with Red and purple instead of blue an green. Also, any two people learning echolocation might make entirely different color-sound associations.

      I still think the answer is ‘no’ or at least ‘highly unlikely’ for reasons explained in my first comment.

  10. I’m a little surprised that many seem to have missed what I thought was quite a straightforward point. What we call colours (red, green, yellow) are the results of different stimulations of sensors, which in turn cause the brain to construct a model of what is happening. Colour is not actually a property of the electro-magnetic spectrum, rather than a property of our brains, which use ‘colours’ to model the effects of light. What Richard Dawkins is saying is that, given a different set of stimuli (sonar) and an absence of light, might the brain model sonar in similar ways to the modelling of electromagnetism? It’s an idea he expressed in the Royal Society Children’s Lectures back in 1991 (was it?) as well as in at least one of his books.

    To me it still seems a good point. The difficulty, though, is that none of us can know exactly what another is “seeing”. Maybe one day well have the technology.

    • Ok, but isn’t the same true for sound already : what we hear ( a high pitch , a voice ) is in reality just ripples of air bashing at a certain frequency against our ears.
      We can also ‘hear’ where a particular sound is coming from, we don’t get a visual cue from that. Just something in our brain which says ‘it was that way’ .

      The same can be said for our sense of smell : we suddenly go ‘french fries’ , ‘fish’ , etc… but we don’t get a visual cue.
      It might have something to do with those senses being very limited though.
      I’m certain it will ‘update the model’ , I’m not so sure it’s going to be through color though.

      In reply to #15 by Pabmusic:

      I’m a little surprised that many seem to have missed what I thought was quite a straightforward point. What we call colours (red, green, yellow) are the results of different stimulations of sensors, which in turn cause the brain to construct a model of what is happening. Colour is not actually a p…

  11. Richard

    I recently read a short essay by Evelyn Glennie (I am sure you know who she is!) about how she ‘hears’.

    I think it relevant to the issues you raise and think you (and others on this thread) might enjoy it.

    See here

  12. Some bats do see in color and others do not.New world bats which tend to be nocturnal and insectiverous, do not see in color
    Old world bats which are frugiverous do see in color (how else do you tell if fruit is ripe when flying up high).
    As for those bats that do not see color, you should study a little bit more about the differences between rod and cone pigment receptors. For instance, rods tend to work wonderfully well in low light situations which cones are physically unable to do.__________________
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  13. Stevie Wonder has a form of synesthesia where he perceives sounds as colours. According to his wiki page he has been blind since shortly after birth so it seems to be possible for a blind person with synesthesia to perceive sounds as colours.

  14. “Bats have had millions of years of evolution to perfect their skills and tune up their brain software.”

    This fraze deduces that the bats did it intentionally, and will
    available a long time.
    If evolution is blind and aimless as alleged, then she has powers that no man has.

    • Evolution is a woman? Is this where the name Evelyn comes from perhaps? I jest. I am afraid your frazes make no sense.

      In reply to #22 by A.Porto:

      “Bats have had millions of years of evolution to perfect their skills and tune up their brain software.”

      This fraze deduces that the bats did it intentionally, and will
      available a long time.
      If evolution is blind and aimless as alleged, then she has powers that no man has.

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