Why would the brain flip the images perceived by your eyes?

  • The following is a common scientific statement, which you don't have to google long for to find:

    The eye views images upside-down in the manner of a camera lens, but our brains reinterpret this input to allow us to see things the correct way up.

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    My first question is quite straightforward: Is this statement valid?

    I don't understand why you should come to the conclusion that your brain should 'flip' the image. Wouldn't your brain be able to cope just fine without flipping it? If anything I would suspect the brain to not flip the image, if there is no reason to do so.

    In order for this statement to be valid, I would expect a scientific theory/experiment from which can be concluded that the brain does process the vision in such a way that, after it being processed all subsequent processing occurs on the 'inverted' image. That seems to me to be the most logical interpretation of 'to flip'.

    I wanted to keep the question short and concise, but as a sidenote, I do know about the experiment where a person wears glasses which inverts their vision after which their vision adapts to it. But this only proves your vision is _able_ to adapt to what you are used to. It doesn't prove that your brain inverts the image initially.

    how would you ever hope to tell apart if the brain flips the image or works with it upside down? It is obvious that the projection on your retina is upside down... but there is functionally no difference between 'right'-side up and 'upside'-down in processing... except for your subjective experience.

    I think it is NOT a valid statement, precisely because it is a meaningless question. If I ask you to tell me whether 1 / 0 = 'something', you can without a doubt say no it doesn't equal 'something', because 1 / 0 doesn't equal anything.

    What it means by "flipping it" is just that it interprets the image received correctly, by understanding that it is presented upside down. The final image that your brain processes matches with your tactile input which interprets everything as right way up.

    @SchroedingersCat: But it's exactly this reasoning I address. From the paper referenced in Artem's answer: _"Spatial relations are not originally perceived by the eye, but are the result of the association of visual sensations with previous muscular and tactual experiences."_ As far as I understand it doesn't make any sense to state "flipping", or "receiving correctly", or that your tactile input does interpret it the right way up. You only know about "the correct way up" by associationg vision with tactile input.

    The point I was trying to make is that it is upside down wrt your tactile input. There is a need to align the two, so that your tactile associations can be related to your visual ones. It is just about relating the various stimuli appropriately.

    I have often thought about this, and surely the most obvious answer should be that the brain doesn't flip the image at all, but that the whole world is in fact in 'reality' 'upside down' (that is what we consider to be upside down). What we 'see' is the upside down image of an 'upside down' world.

    @Tomp24 Welcome to Stack exchange and thank you for sharing your thoughts! However, 'upside down' is a subjective percept; it is constructed by and with respect to the viewer. The world cannot be upside down 'in reality'. The world is. And we perceive it.

    there is also an experiment in which you may use a spoon in order to test this theory.

    Who can prove that world is in a mirror? Left brain control right body and opposite. Does it be possible that real world is swipped by brain. Reality is relative.

    What does it mean to flip? We know that a pair of lens can flip the image. And might not, depends on focal distance. It's said that if our eyes were lens then they would flip the image. But I thought this makes no sense: with only lens instead of eyes I would be blind. It is brain who decides where is top and where is bottom.

    As I stated in the question, @rus9384, my interpretation of 'to flip' would be that _"the brain does process the vision in such a way that, after it being processed all subsequent processing occurs on the 'inverted' image"_. But, as pointed out by the answers, it is not meaningful thinking about 'brain processing' like that.

  • It is not meaningful to talk about your brain processing something as 'right-side up"' or 'upside-down'. The 'images' in your brain are just collections of neural activations, and not actual pictures. Thus they cannot have an orientation. The only meaningful way to test your question is to try flipping the input the brain receives and seeing if it can cope.

    Fortunately, the brain is capable of flipping your visual field if required as measured through perceptual adaptation experiments using inversion glasses. This has been demonstrated very drastically in studies, by for instance requiring a participant to wear inversion glasses for a long time. At first they are confused, and unable to orient themselves and do basic tasks, however after enough time the brain can adopt enough to even do activities like riding a bike. This suggests that from the only way you can measure things (i.e. behaviorally) the brain is capable of adapting to an upside down world (some participants even reported that after extended use the world even seemed "right side up"). This is functionally equivalent to the brain being able to process your visual information in either orientation. If it is capable of processing in either orientation, the question of "does my brain flip the image" becomes a pseudo-question and unanswerable.


    • Taylor, J. G. (1962). The behavioral basis of perception. New Haven: Yale University Pres

    • Harris, C.S. (1965) "Perceptual adaptation to inverted, reversed, and displaced vision." Psychological Review 72(6): 419-444. [pdf]]

    • Di Paolo, E.A. (2003) "Organismically-inspired robotics: homeostatic adaptation and teleology beyond the closed sensorimotor loop", {Dynamical systems approach to embodiment and sociality: 19-42 [pdf

    As in my comment, I know about this study. In informal discussions it is most often used as a proof your brain 'does' flip images. As you state, I never understood the reasoning behind this, and your answer confirms my suspicion it is just an urban myth.

    Thanks for the paper! _"Spatial relations are not originally perceived by the eye, but are the result of the association of visual sensations with previous muscular and tactual experiences."_ _"This belief in the primacy of touch **is so ingrained** that experimental results are sometimes flagrantly misinterpreted in order to support it."_ .... _Finally_ I have a conversation stopper! Such a fun feeling when your intuition turns out to be right. :)

    Nice answer.I'm not an expert but i'd like to share a personal experience attached to this, I'm myopic with cylindrical power,when I started wearing specs, in those days, I felt as if my height had increased and it was very difficult for me to make the adjustments, my steps used to falter, later on, I believe my eye-brain co-ordination have made reasonable progress, I don't have that issue anymore. http://physics.stackexchange.com/q/228077. Why can't we say that the new born baby see the world very differently, `Babies learn to see over a period of time, much like they learn to walk and talk.`

    Reminds me of a lyric in "Clint Eastwood" by Gorillaz - "Y'all can see me now 'cause you don't see with your eye. You perceive with your mind".

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Content dated before 7/24/2021 11:53 AM