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Sophie Rand

Student Engineering, The Cooper Union For The Advancement of Science and Art


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Can we ever know how another person "senses" the world?

In my Bioelectricity class this week, we learned about the cells
in our body that help us sense our environment: chemosensors in our
tongue that help us sense taste, for example, the photoreceptors in
our eye that sense light, and the hair cells in our ears that sense
the mechanical vibrations of sound, to name a few.

As a result, I recently revisited my answer to the age-old question of
“how do I know that the blue I see is the same blue you see?” that was
so startling and exciting to most 3rd graders playing baby Kierkegaard
a little bit differently. An answer could be that we just have to
trust that perception is guided by biology and that humans are
biologically identical to within 80% of our biological systems.

This answer, of course, raises new questions: even if you and I may
perceive the same blue, is that blue "real?" Where does sensation
leave off and perception begin, and how may we trust ourselves as we
try to compare them? Can we ever know how another person "senses" the
world? Would love to hear your thoughts!


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  • Feb 19 2012: From skimming this page I see that most people took the stance that we can never know how another person senses the world. However, I don't see how we can be so sure that this is impossible: We can never actually know the extent of our knowledge. For example, in the middle ages, who would have thought that we could actually travel to the moon or sequence our own DNA? My assumption is very few, if any. Expansion of knowledge is hypothetically limitless.
    We sense things only because a certain number of parameters exist in our bodies - our nervous system, more precisely - and the cells in this system react in generally the same way from human to human. Let's not forget that the DNA across humans is actually very similar. Furthermore it is actually very similar to the DNA of other organisms.
    I would say that we do have the ability to perceive the world as another person does; for example, what if some day we could take a machine like an EEG and connect it between two people, causing the electrical impulses to travel between the two people. I am positive that this achievement would be extremely difficult, but I am not at all convinced that it is impossible.
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      Feb 20 2012: Hey Eric,

      I agree, I believe that in the future, it may totally be possible to know exactly how another person senses the world. You already listed a couple examples disproving the limits of knowledge, and here is yet another one: http://www.ted.com/talks/sheila_nirenberg_a_prosthetic_eye_to_treat_blindness.html

      In this video, Sheila talks about the signals produced by the retina, and how new technology has been developed that actually mimics these signals and transmits them to the brain, so that people with deteriorating retinas can effectively see.

      For the question at hand, this is very encouraging. While complex at its own level, the solution seems simple -- we just need to determine where in the brain our senses are and where our perceptions are formed, and how we can interact with these parts.

      The dangers of this, as Timothy James has pointed out, however, are numerous. With the the power to change how someone perceives something comes a bunch of ethical responsibilities. Suppose someone didn't like eating their vegetables - all we would have to do is implement our findings and change their perception: vegetables taste good, not bad. Alright so maybe that wasn't so bad. But imagine the exploitation of such power in the military, that's where things can get scary.

      In my opinion, I don't think this is a road we should travel. To be able to alter someone's perception like that seems inhumane. By doing so, we remove identity. People would not be themselves, but who we want them to be. While I believe it can be possible to see how another senses the world, I don't think we should go about finding out how because the results could be more harmful than beneficial.
      • Feb 20 2012: I agree with you that this technology could be incredibly dangerous. In a recent practice debate at school we discussed whether the technology used in Inception would be moral or not. The ultimate conclusion was that the human mind is above all else because it is the only thing that we can keep entirely to ourselves. Of course, Maslow's Hierarchy of Needs places physiological needs first but that is beside the point that the privacy of the mind should not be violated.
        If used for the purposes of gaining information, then yes, I certainly agree that this technology is a bad idea. However, if used to achieve a greater sense of understanding between humans… well, that could be a very good thing. We have to consider which of the options outweighs the others, taking particular notice to whether the dangers justify the possible good.
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        Feb 21 2012: Andrew,
        i definitely agree with you that the knowledge to understand human perception is within our grasp given enough time. Sheila Nirenberg's talk about prosthetic eyes to repair retinas was mind blowing. It's incredible to imagine having the ability to recreate the complexity of visual perception.
        While, yes, such science could lead to dangers, can't all realms of science? We can't hinder scientific progress and discovery because we're scared of how people might abuse it. There will always be those who try to exploit technology for their own personal gain, and it is up to us as a society to protect the purity of science and use it only for good.
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        Feb 21 2012: Although much more understanding about how another person visualizes and senses the world will become available to us in the future, I think that we have a huge overlap even now. As the video linked above shows in talking about the prosthetic eye, if we understand the code or the language of the brain from one person, things suddenly become possible that weren’t possible before (making the blind see). We already know that in the “normal” or average range of emotion, certain events will elicit the same response, meaning that we sense (whether it is seeing or hearing or smelling, etc) the same things to a close degree. We shouldn’t discount that our being social creatures mean that we have this amazing capacity to relate and understand one another. You could sum it up in the word empathy, which is a product of the senses and allows another person to feel what others are feeling and express it back to them. As people have said, this understanding will undoubtedly increase in the future, but we already have a base from which we do start.
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          Feb 21 2012: I agree with the general sentiment that for the most part we as human beings do sense the world in the same way. If we didn't, projects such as the prosthetic eye would not work as they would have to be tuned to each individual user. I believe that this similarity is due to the fact that one can think of each cell as an individual sensor which either fires and is thereby encoded and later interpreted in the brain or not. The similarity in this process between individuals is understandable (due to the overlap in genetic code) which would lead to the conclusion that people sense the word in the same way. However, the question I have always had and I think is implied here is about the perception of the world, the way in which the combined signal in its entirety is created, interpreted and perceived. This I believe must be different from person to person because otherwise we would all be great at sports with terrific hand eye coordination, or artists with a sense for color and lighting in a painting or wine connoisseurs with the ability to sense hints of different ingredients. Since this is not the case to me it must be that while individual cells may very well "sense" using the same mechanisms the collection of these senses is different from person to person making up a varied view of the world. Color blindness I feel is just an obvious example of how people do indeed perceive the world in different ways suggesting to me that likely the sky is slightly different shades of blue to different people.

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