Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

About the Eye

  1. May 15, 2008 #1
    From my limited knowledge of the physics of the human Eye.. I got the impression that the
    image enters the brain via optic nerve which I always assumed to be an electrical impulse
    circuit. But if this were indeed the case, vision interpretation would be purely a psych/brain
    function. The question I have is this: Has a human *ever* seen the real world?

    Bizarre question, an electrical impulse from a nerve to the brain is NOT true vision but
    rather something the brain perceives, interprets as sight. I guess the same could be true
    of the other senses as well... hearing, touch, taste, etc are just signals that the brain
    interprets. Im no biology expert, but science teaches me these things that my simple brain
    has a hard time accepting or fully understanding.


  2. jcsd
  3. May 15, 2008 #2


    User Avatar
    Staff Emeritus
    Science Advisor

    What do you define as "seeing the real world"?
  4. May 15, 2008 #3
    I'm wondering what you mean by the "real world," as well.

    I mean it's nothing new that humans perceive the world differently than lets say, a dog, does. We have a limited hearing frequency range, we can only see only so many dimensions, we can only smell things so well, etc., etc.
  5. May 15, 2008 #4
    Well I would define "real world" as the place where we exist/live and breath. Would there be another definition could one infer? My point here is that an electrical impulse to the brain isnt really a definition of seeing or vision. I mean there is just interpretation of light/color/texture, etc and the brain makes the image correct? or is the image made prior to brain? (ie. in the eyeball or nerve) the emphasize should be on what is "seeing or vision" and where does it occur. Thanks for the input if you have any.

  6. May 15, 2008 #5
    BryanP, are you implying there are other dimensions that cannot be seen? That's kind of what I am driving at here. The lack of proof doesn't mean it doesnt not exist, just not measurable according to scientific protocol.
  7. May 15, 2008 #6

    Andy Resnick

    User Avatar
    Science Advisor
    Education Advisor

    It's been a central tenet of western philosophy for centuries that we cannot directly interact with the external objective world. Everything is 'filtered' through our senses.

    This does not mean that we cannot obtain an accurate representation of the external world through scientific study.

    Or are you asking something different?
  8. May 15, 2008 #7
    Well, it seems that "back in the day" scientists (Kant/Tesla in particular) had alot to say about the eye/vision and things such as Empirical reality/Transcendental Ideality, etc and their seems to be a great deal written about the metaphysical by many famous scientist *despite* the factor that their concepts could never be tested by scientific protocol. I can't dismiss alot of bunk that I can't see (magic/ghosts/etc) however I have lately been able to clearly visualize ideas in my mind, some of which are quite detailed and vivid. Im sure that many ppl have this ability but I wonder how/why I can see something that only
    exists in my mind. It is a strange phenomenon for sure.


  9. May 15, 2008 #8


    User Avatar
    Gold Member

    Vision is defined as the ability to interpret information from visible light reaching your eyes. So if we have false vision, what would real vision be?

    Let's just say that the objective nature of something is totally different than what we are ever capable of perceiving. Why would it matter to us?
  10. May 15, 2008 #9
    There is a lot of image processing that occurs in the eye before the signal travels down the optic nerve to the brain. We evolved to perceive edges and motion; much of the processing that extracts these features from our visual field occurs in the retina and the signals that travel to our brain are enriched in edge-and-motion data compared to flat-field data. Is that the "real world"? It is, at least, the part of the real world that helped my ancestors survive through reproduction.

    Note - vision research isn't my field, this is gleaned from reading popularizations.
  11. May 15, 2008 #10
    It seems to be a question of direct realism versus representationalism.
  12. May 15, 2008 #11


    User Avatar

    Staff: Mentor

    Since the brain is an electrochemical device, how else would we "see" besides having the light signals translated into electrochemical signals?
  13. May 16, 2008 #12


    User Avatar
    Science Advisor
    Homework Helper

    Holography comes to mind.
    Not a minimal energy solution though.
    I would be a huge energy drain on a biological system,
  14. May 17, 2008 #13
    Hologrphy is a fascinating technology... Reminds me of magic. Smoke & Mirrors and that sort of thing. but I dont understand how it would be a biological drain. What do you mean by that?


  15. May 17, 2008 #14
    Wow... you got me thinking in whole other direction. There was a good Wiki
    on Holonomic brain theory. I just wish there was more scientific info on this topic.
    Any experts out there??

    again thanks for the thought provoking notion. Its like a whole other world, brighter than

  16. May 17, 2008 #15


    User Avatar

    Staff: Mentor

    I don't know if this explanation is too basic, if it is, I can find something more detailed.

  17. May 17, 2008 #16


    User Avatar
    Science Advisor
    Homework Helper

    The organism would need to emit coherent light or in other words it would have to have a biological laser.
  18. May 17, 2008 #17
    The brain is an amazing device and I also experienced some very bewildering revelations of knowledge about the mind. I would suggest reading an introductory nueroscience book.

    Oh, and not just the section on vision!! :wink:

    The more you know about the world around you (and the one inside you) the more empowered you become!!!
  19. May 26, 2008 #18
    The answer is obviously yes -- but I understand your concern. This was a major strand of Kant's work. In the world there are the "things in themselves", or noumena. But we only ever get access to sense experiences, or phenomena.

    So an interesting question presents itself - how much of the phenomenal world is contributed by the noumena, and how much is contributed by us? Kant thought many features of the phenomenal world, such as colour, causation and categories of things, were contributed by us.
  20. May 27, 2008 #19
    Yeah Holograms to create Hyperspace...

    A actual Holodeck would be ****! The Eye has always fascinated me for a number of reasons. They are windows to the soul according to the Bible, however you can't trust em.
    To get the real pic... you have to use the 3rd Eye...


  21. May 27, 2008 #20


    User Avatar
    Gold Member

    To tell the truth our senses all work together to give us as accurate a description as possible about our environment. The thing is that we have an "internal" environment as well that tends to mess up the signals we're bringing in from the external one.

    For instance, without sight, our hearing is partially impared because the eyes are always helping us determine the direction a sound is coming from.

    When we can touch, sense the pull of gravity, smell the ozone of lightning or smoke of a fire, when we can taste the breeze off of a flowering orchard we see... this begins to give us the "triangulation" we need to determine where we are and what the "real world" is doing... outside of our senses.

    edit: what you may be referring to is the fact that our senses do not go as far as being able to observe molecular structures or atomic levels of our every day environment. In an upcoming thread I'm going to address the fact that, even though we don't see something, we are aware of it, have knowledge of it and are able to incorporate that information into our daily lives.
    Last edited: May 27, 2008
  22. Jun 9, 2008 #21
    That concept of all processes working together to achieve "triangulation" is real insight.
    Humans need biofeedback to become oriented to their environment. I am trying to come
    up to speed on neuroscience, and there seems to be anecdotal evidence that strange things occur between the conscience and unconscience mind. Hallucinations/Vision, etc. Of course there is no real world measurement of what occurs in the psyche except perhaps the output of an EEG machine. The EEG measurements are like really old school analog measurements of brain impulse thru the cranium. In this day and age, you would think we would more sophisticated ways to measure key brain functions.

    In mental institutions there is a mixed bag of conventional medicine, electro convulsive shock therapy (ECT), REM hypnosis (EMDR), meditation, guided imagery, yoga and progressive relaxation taught as either a coping skill or way to recondition/reprogram the brain. There is a real medical science that supports the results achieved thru these techniques, but to my knowledge there is no way to measure the experiences or results.... (besides clinical trial/surveys) We kinda blindly follow that what doctors/therapist do as being in our best interest. We are however, human guinea pigs.

    There was a pretty good (and thought provoking) writing on the eye by Nikola Tesla at



    Last edited: Jun 9, 2008
  23. Jun 9, 2008 #22


    User Avatar
    Gold Member

    You have to survey each patient and try to come to the interview with a standard language for each sensation.

    But, the results of meditation, relaxation can be seen in studies on survival of cancer and show a 20 percent survival increase due to relaxation practices.

    I was involved in a program like this, vicariously, and I can try to dig up the stats if you like.
  24. Jun 9, 2008 #23
    There are many things that we can't see....such as x-rays, gravity fields, magnetic fields (although we can observe some effects of them).

    Also, our brains can be tricked, or our brains can interpret things differently....not just from person to person, but just within our own brain.

    For example...optical illusions...

    Last edited by a moderator: Apr 23, 2017
  25. Jun 9, 2008 #24


    User Avatar
    Gold Member

    Yeah, for sure, and optical illusions present a major puzzle here as well.

    I mean, the Fun House is full of them where you think you're walking into the distance and you whack into a wall.

    Optical illusions can illicit visceral responses such as heaving, falling down, dizziness or a feeling of weightlessness. I mean its fascinating how much vision effects the rest of the body... not that the olfactory or aural senses don't have as much power. Combined, sight, hearing and smell could end up killing you... just by sheer inundation.

    I think someone has linked us to optical illusions here but here's s a great study of some classic optical illusions...


    However, if you really boil down how the eye will trick the body... its usually in defense of life. In other words, the optic centre of the brain seems programed to interpret all visual stimulus as either a threat to survival or as a way to continue to survive.

    So, we often see a strange lump in the forest as a threat... then when we see a lump on a table it looks like food or something that might continue survival. When an optical illusion makes us fall down we are falling to avoid something that's even worse that we have perceived to be taking place because of the illusion. This is protective and defensive behavior stemming from the cerebellum whose function on is to coordinate and regulate muscular activity..... according to all visual, aural, tactile, olfactory etc (sensory)... cues.
    Last edited by a moderator: Apr 23, 2017
  26. Jun 9, 2008 #25
    Yeah, really all higher functions of the brain take a back seat when comes to survival. It takes whole lot of mental abuse or indoctrination to overcome the urge for self-preservation and procreation. I think we forget our humble bacterial beginnings.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook