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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 15 2012: Pratyeka,

      You say, 'it is irrelevant as far as communication goes.'

      Perhaps, but keep in mind -

      "How charming it is that we have words and tones; are not words and tones rainbows and illusory bridges between things eternally separate?
      To each souls belongs another world: to each soul every other soul is a back-world.
      Among things most alike, the resemblance decieves us most delightfully, for the smallest gap is the most difficult to bridge.
      For me -- how could there be an outside of me? There is no outside! But we forget upon hearing tones. How delightful it is that we forget!...
      It is a beautiful folly, speaking: with it, man dances over everything."

      -Nietzsche, Thus Spoke Zarathustra

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          Feb 16 2012: Hi Pratyeka,

          You're pointing out an interesting characteristic of language, which is that it is a contract-- that is, we all agree on the meaning of a word. The reason the question of 'are you saying the same blue as i am' is interesting is because of the solipsism of perception and even the solipsism of language-- that no one can know what an individual perceives or believes to be true. That's true even if there is something blue and two people both agree that it is blue, the language is lose in the sense that the language does not really prove that we mean the same thing by blue
        • Feb 16 2012: No, Pratyeka, it is you that misunderstood.

          I agree that in terms of the conversational dynamic, subconscious mental activity is irrelevant.

          I was just pointing out (and letting Nietzsche speak for me) that in terms of subconscious mental activity, language is irrelevant, as it is a veil that cloaks true understanding as well as misunderstanding.

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      Feb 15 2012: "The blue is independant of our perception of it."

      I don't think that's really true. The spectral characteristics of light reflecting off an object are independent of our perception, but how that spectral distribution of light gets turned into a color is 100% perception. Maybe a better way to ask Sophie's question would be: what does color look like to tetrachromat (eyes with four types of cones)? Can we ever communicate this or understand what the world looks like through senses that are different from our own?
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          Feb 16 2012: "The source of the "blue" is independent of our perception of it because if I'm not present, the source of the blue is still there, independent from my existence."

          The source of color may be there, but there is no color without the perceiver. Color happens inside the head. Without our perception, the only thing you can measure is the wavelength and power of the light. That is NOT color—it is watts and nanometers. Color doesn't happen until it is perceived. This is why if you want to transform measurements taken from a spectrophotometer (i.e. watts and nanometers) into a color specification you need subjective data taken from actual observers. (For most color science this is in the form of the CIE standard observer data).
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      Feb 17 2012: Just putting this out there for what it's worth since this thread's talking about color perception. "Color Perception Is Not In The Eye Of The Beholder: It's In The Brain" http://www.sciencedaily.com/releases/2005/10/051026082313.htm

      Basically, everyone has different densities of photoreceptors in the retina yet we all perceive color the same way (read their paper to see how they confirm this). In the experiment, the subjects' color perception was also shifted by wearing tinted lenses and in time they would feel as if wearing the tinted lenses was normal and without them the colors seemed off. This suggested to the researchers that we have some sort of built-in auto calibration for color in our brains.

      As for whether we perceive color the same way among different people in terms of culture (the way we describe it, the way we associate it with other things) I would have to say yes. Although it's harder to show a complex relation between stimuli and what we consider as "sentient" thoughts, keep in mind, we do not perceive colors as stimulus in discrete color channels, in fact we can't experience colors individually. We experience colors in pair, and our brain relies on the lack of color simuli to perceive color. This system in itself is complex, yet we happen to evolve in a way where we can say for certain, blue is blue; and if you believe the paper mentioned above, the ability to agree on the color blue is calibrated, meaning, we all go through similar calibration and synchronization processes in order to be in agreement. If that is the case, then can we not extend this belief and say that in order for language to have evolved, we needed to have some built in way of synchronizing all of our perception in order to be able to communicate?
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        Feb 17 2012: Colour perception varies with culture and the environment. In Amazonia people perceives different kinds of green, because there's green all around. In Antarctica, they perceive a lot of white tones because, once again, they are surrounded by that colour. And they have the words to name them.

        Not everyone can distinguish between orange and red, for example. The perception of colour has many variants: culture, environment, our eyes and brain, light conditions, etc
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          Feb 17 2012: I think at the root, the question is whether a person's perception is exactly the same if he/she has experienced the same exact stimuli (so if they were brought up in the same culture, in the same environment, etc).

          As the paper I've referenced has shown, people are capable of calibrating their internal references to colors. We cannot know for sure whether people not from Antarctica can perceive a lot of white tones if they were transplanted in Antarctica and given time to adjust. We need to test this out through experimentation before we can make conclusions. I believe they will auto-calibrate their color scale in order to perceive those slight variations in tones. If that's the case, then can we not make the conclusion that if people were placed in the same situations, they should be able to calibrate their perception such that it's the same as each other?

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