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Why did evolution create conscious states of mind?

When we open our eyes in the morning, we take for granted that we will consciously see the world in all of its dazzling variety. Likewise, when we consciously hear conversations with family and friends, consciously have feelings about them, and consciously know who they are.

The immediacy of our conscious experiences does not, however, explain how we consciously see, hear, feel, and know; where in our brains this happens; or, perhaps more importantly, why evolution was driven to invent conscious states of mind. I will summarize some of the reasons here, starting with why we consciously see. My answer will propose, in brief, that we consciously see in order to be able to reach. 

Being able to make an arm movement that reaches a nearby object cannot be taken for granted, if only because of the way our eyes process light from the world. Seeing begins when light passes into our eyes through a lens and hits our photosensitive retinas, much as occurs in a camera. However, our retinas are not manmade. They are made from living cells that need to be nourished at a very fast rate. In addition, the light-sensitive photoreceptors that comprise a retina send their signals to a brain using an optic nerve. These two factors force our retinas to pick up visual signals from the world in a very noisy and incomplete way, as the first two images illustrate.

Figure one (top); figure two (bottom)

Figure one shows a cross-section through the eye, showing the lens on the left and the retina on the right. The photodetectors send their light-activated signals down pathways, called axons. All the axons are collected together to form the optic nerve, which sends all the signals to the brain.

Figure two shows that the part of the retina behind which the optic nerve forms is called the blind spot because there are no photodetectors there. Note that the blind spot is about as large as the fovea. The fovea is where the retina can form images with high acuity. Our eyes move incessantly through the day to point our foveas to look directly at objects that interest us.

In addition, retinal veins that nourish retinal cells lie between the lens and the retina, and thereby prevent light from reaching retinal positions behind them.

We can now begin to understand what it means to claim that conscious seeing is for reaching. This is true because, as illustrated in figure three, visual images are occluded by the blind spot and retinal veins. Even a simple blue line that is registered on the retina is sufficient to illustrate why this is a problem. Suppose that, as in the figure, the blue line passes through positions of the blind spot. Because the blue line is not registered at those positions, without further processing we could not reach for the blue line at any of these positions. The brain reconstructs the missing segments of the blue line at higher processing stages so that we can, in fact, reach all positions along the line. The same problem occurs no matter what object is occluded by the blind spot or the retinal veins.

Figure three

This is not a minor problem because, as I already noted, the blind spot is as big as the fovea.

But what does this have to do with consciousness?!

As I will indicate below, it takes multiple processing stages for our brains to complete representations of images that are occluded by the blind spot and retinal veins. But then how do our brains know which of these processing stages generates a complete enough representation with which to control reliable reaches? Choosing an incomplete representation with which to control actions could have disastrous consequences.

The answer lies in the claim that “all conscious states are resonant states.” I will explain what a resonance is in a moment. For now, the main point is that, a resonance between a complete surface representation of an object and the next processing stage renders that surface representation conscious. Once such a complete surface representation is highlighted by consciousness, it can control actions. And because it is complete, this representation can successfully control accurate reaches to any position on an attended object that is sufficiently near.

Figure four

The selection of complete surface representations occurs in prestriate visual cortical area V4, which resonates with the posterior parietal cortex, or PPC, to generate a surface-shroud resonance. As illustrated in figure four, spatial attention from the PPC can highlight particular positions of the V4 surface representation via a top-down interaction, at the same time that spatial intention can activate movement commands upstream to look at and reach for a desired goal object.

A resonance is a dynamical state during which neuronal firings across a brain network are amplified and synchronized when they interact via reciprocal excitatory feedback signals during a matching process that occurs between bottom-up and top-down pathways, like the pathways between V4 and PPC. Resonant states focus attention on patterns of critical features that control predictive success, while suppressing irrelevant features. They also trigger learning of critical features—hence the name adaptive resonance—and buffer learned memories against catastrophic (sudden and unpredictable) forgetting.

The conscious states that adaptive resonances support are part of larger adaptive behavioral capabilities that help us to adapt to a changing world. Accordingly, resonances for conscious seeing help to ensure effective looking and reaching; for conscious hearing help to ensure effective auditory communication, including speaking; and for conscious feeling help to ensure effective goal-oriented action.

Figure five summarizes six types of resonances and the functions that they carry out in different brain regions.

Figure five

Surface-shroud resonances derive their name from the fact that surface representations resonate with spatial attention that covers the shape of the attended object, a so-called attentional shroud. Surface-shroud resonances support conscious seeing of the object, whereas feature-category resonances support conscious recognition of them. When both kinds of resonances synchronize, we can consciously see and know about familiar objects.

What processes are needed to form a complete surface representation from the noisy retinal images that are occluded by the blind spot and retinal veins? First, the blind spot and retinal veins themselves are removed from this representation. This happens because they are attached to the retina, which continually jiggles in its orbit, thereby creating persistent transient signals on the photoreceptors from objects in the world. Retinally stabilized images like the blind spot and retinal veins fade because they do not cause such transients. Next, our brains compensate for changes in illumination that occur through the day and that could undermine the processing of object shapes. Finally, our brains need even more stages to complete the boundaries and fill-in the surface brightnesses and colors that are occluded by the blind spot and retinal veins, as illustrated by figure six. Conscious states enable our brains to select the complete boundaries and surfaces that result from all of these processes.

Figure six

Feature image: S Migaj via Pexels

Recent Comments

  1. Ahmes

    Great to tackle this mysterious concept of «  Consiousness ».

  2. David Glidden

    Very informative! But as a philosopher, the case for conscious seeing seems to imply that conscious seeing is to be found in other species, besides humans. How far down the phyla does this extend? Dogs, yes. Owls? Bees?

  3. Amande

    I’m not sure about what conscious is this article. Human conscious is far different from the animal one which are supposed not to have one. So I am not convinced by this text.

  4. Jaedon

    Does this answer the questions to life? Yeah you can look at consciousness scientifically of course, with anything really. But does studying consciousness in any shape or form useful in the web of science?

  5. Michael Felock

    The eye
    Brain
    Movement of an appendage
    Shroud
    Thank You!

  6. Frederick B Parkhurst

    Consciousness arizes out of reality not the other way around,

  7. Nathan Raboin

    This is a very interesting read. I think a lot about consciousness, and I think it’s very important to nail down a definition going into the future with our advancements in machine intelligence.

    I’m curious about the implications of this for future artificial intelligence. You say (very simplified, apologies if I misrepresent), that in our case, our consciousness evolved in order to enable our looking and reaching to overcome a blind spot in our retinas. If true, what does that say about any theoretical future advanced general machine intelligence?

    Would it not be able to gain consciousness in the same way as us, since it presumably wouldn’t have the same limitations? Or would it be able to gain consciousness by a different means that ended up being functionally similar?

    This is a very interesting idea and I’m very intrigued by the possible implications.

  8. Tim

    Why did evolution create? Evolution “create”?! What a load of presuppositions and question begging. Consciousness was created by God (through evolution) so we could enjoy God. Poor friend, You don’t realize what your flat little outlook keeps from you. Open up.

  9. Paul Sawayer

    Fascinating explaination that may provide an indirect model of consiousness but still does not provide a satisfactory answer for the evolution and existence of the experience we call consciousness. The research “reaches” for the answer to the old queries of “what comes first the chicken or the egg” or “a tree falling in the forest” which remain.

  10. Frank Spence

    By definition, in material systems the mechanisms that lead from visual input to any output must be explainable in physical terms. There must be a complete physical explanation. Physical explanations involves structure and function. Physical explanations have neither the need nor an explanation for subjective experience except as a metaphor for the actual physical processes involved. And since subjective experience is the only indubitable phenomenon, all else being logical constructions based on experience, there is a fundamental flaw in the theory of materialism.

  11. dildrum

    Because survival requires situational awareness and once consciousness arose it began diverging into competitors in a technological neural race. Self awareness is just a special case of situational awareness.

  12. Glynn Evans

    Very nice article. Might I suggest some expansion: we consciously see so that we may move throughout a world that is represented on our brains in a data efficient (compressed, “lossey” ) manner. The representation is a construct which relies on post data collection processing and attention-guided refraction (via a variable focal length lens).
    Merely collecting photons does not provide something consciously navigable without extravagant processing power. A lens plus filing in gaps through higher level processing is more efficient than striving to capture sufficient data to produce a hi fi image. Thus, missing a few steps in between, the usefulness of directed movement inevitably (?) leads to the evolution of consciousness in a power-constrained brain. This overlaps somewhat positively with attention schema theories.

  13. K. Srinivasan

    I think consciousness is not part of the human biology.. It is sn intelligent force beyond the human system which gives life to the system ,uses the senses and thec brain to experience the world. When it leaves a person he is supposed to be dead. This borders on metaphysics.

  14. luis padron

    As far as I can see consciousness isn’t necessary for any of it.

  15. Johann Popper

    Certainly this is the case, but one must start the argument by defining ‘why’ and ‘how’ and ‘explains’. That area is the sole locus of confusion. Everything else downstream is just pure, indisputable empirical data about the function of biological systems, as you’ve illustrated. Controversy about this issue is simply due to undereducated (in philosophy) people who have not yet categorized their concepts coherently, or who are neurologically unable to do so. To demonstrate, grammatically, the question of ‘consciousness’ is no different as a noun than a discussion about the ‘laws of nature’, whereby we imagine powers underlying the obervable motion of things. The internet has made everyone tjink they are experts, even in fields of which they have no education (such as grammar, or logical categorization) or even awareness, and it’s really an intolerable chaos injected into the academies, and should not be perpetuated by over-specialized PhDs of the university subfields.

  16. Christopher Scott Campbell

    It’s almost as if the author has no idea what the mind/body problem is.

  17. Mike McClelland

    I don’t see any mention of us having two eyes, and the brain using info from both to create the final image. Gaps in visual info caused by veins in one eye will be filled in with visual information from the other eye

  18. Ken

    So smart, yet so ignorant. Evolution did not create consciousness, consciousness created evolution and everything else in our universe. We choose to forget this to incarnate here, but consciousness animates our body. When it leaves at death, we understand.

  19. Marius Malan

    Evolution didn’t. Creation did

  20. Daniel Fausto

    Evolutionism!

  21. Marius Malan

    Conscious state of mind can not in any way, shape or form evolve. It has to be created. To speculate about the evolution of consciousness is the height of foolishness

  22. Inventzilla

    There’s a lot more to it than reaching things like monkeys swinging in the trees. Are raccoons conscious like people? They have oposable thumbs.

  23. Andy Smith

    Evolution didn’t,God did!!

  24. Barney Mezey

    Interesting but how come blindness is not even thought of in this article? So blind people don’t count? Of course there are different types, the ones that cannot see since birth and the ones who had lost their eyesight due to some other causes. But the former would experience the world around them completely differently.

  25. Marius Brez

    The title question is invalid. Evolution is not an entity, commits no action and cannot create. The question “why” also presupposes such an entity, and its intentions. On all metaphysical questions, the question can only be how. On the chance that this was not the author’s fault… I will review more thoroughly when timely.

  26. Joshua Sweatman

    Not all conscious life uses photoreceptors.infact in a lot of animals its not even their primary sense.

  27. Jack Vintage

    Evolution created conscious states so as to process data. We survive so successfully as a species because of our ability to transfer data so efficiently. We transfer so much data that it takes generations (and lots of us) to sort out and discard irrelevant data. Combined with the fact that our environment is always shifting decade to decade this has become increasingly more complex. When nature is our only concern the information is pretty straightforward. However as humans we have constantly been shifting and altering our environment that it has all become quite a complex situation. As a species we have become our own greatest threat and that has overloaded the system. Our data sorting is responding to a psychological and mental overdrive more than anything else. We have completely overloaded the system. We are adapting but it has taken a good few generations to work out what we need to do. I wrote a much more detailed comment but it didn’t get posted for some reason. It’s all about perspective. But the simple thing is data. We need it to survive. Consciousness is how we process it. We do it as individual nodes on a complex human network. We only need to actually look at the world we created and the language we use. It’s a reflection of the inside. God creates in the image of himself.

  28. Steven Prentice

    What a load of rubbish. How do you explain a soul, your thoughts, feelings and emotions. God created everything in existence, not a bang from nowhere. You have to be completely stupid, which the holy bible does say, people are stupid, Proverbs 12. However the truth is, people create a lie like evolution to hide the fact that judgement will happen Roman’s 1. The whole of creation proves God exists in Jesus.

  29. Alex S

    This is so funny to read. Plus all the comments of people who think they figured it out. Some of you are convinced your theory is true. We are still a planet of idiots with no clue about how and why we became “this”. All of the ideeas are pure imagination. My dumb theory is that we are, what ever we want to be. We’re a continous create and perceive force, like a paradox, just like the universe, no start no end, just infinite. We create ourselves as a conciousness, we manifest into reality and then we experience ourselves. Infinite, paradox, these are the keys.

  30. Charles Urban

    Consciousness is over-rated. It’s not the big of deal. Yes, Descartes discovered self-consciousness. Great. May we move to other philosophical topics now?

  31. John

    There is a brilliant description of how the location of current Experience is most likely to be non-cortical in this short book: http://thereandwhere.com/antsand.html

    Well worth looking at.
    (link also on “website” attached to this userid).

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