The Real Science (Not Armchair Science) Of Consciousness

Among brain researchers there’s a truism that says the reason people underestimate how much unconscious processing goes on in your brain is because you’re not conscious of it. And while there is a lot of unconscious processing, the truism also points out a duality: your brain does both processing that leads to consciousness and processing that does not. As you’ll see below, this duality has opened up a scientific approach to studying consciousness.

Are Subjective Results Scientific?

Researcher checking fMRI images.
Checking fMRI images.

In science we’re used to empirical test results, measurements made in a way that are verifiable, a reading from a calibrated meter where that reading can be made again and again by different people. But what if all you have to go on is what a person says they are experiencing, a subjective observation? That doesn’t sound very scientific.

That lack of non-subjective evidence is a big part of what stalled scientific research into consciousness for many years. But consciousness is unique. While we have measuring tools for observing brain activity, how do you know whether that activity is contributing to a conscious experience or is unconscious? The only way is to ask the person whose brain you’re measuring. Are they conscious of an image being presented to them? If not, then it’s being processed unconsciously. You have to ask them, and their response is, naturally, subjective.

Skepticism about subjective results along with a lack of tools, held back scientific research into consciousness for many years. It was taboo to even use the C-word until the 1980s when researchers decided that subjective results were okay. Since then, here’s been a great deal of scientific research into consciousness and this then is a sampling of that research. And as you’ll see, it’s even saved a life or two.

Measuring Tools

The number of methods and tools for examining the human brain has grown over the years. The first was to learn from neuropsychology patients who suffered brain damage, correlating which areas were physically damaged with the resulting effects. Then there are the type of experiments often associated with psychologists where subjects perform tasks and their behavior is monitored to test some hypothesis.

Another early method was the insertion of electrodes into the brain, usually while patients are undergoing surgery. The advantage of electrodes is they can be used to both monitor neuronal activity and to stimulate it.

EEG example.
EEG example. Credit: Der Lange CC BY-SA 2.0

Electroencephalography (EEG) involves the placement of electrodes on the scalp to measure voltage fluctuations resulting from ionic current in the brain’s neurons. It’s an old method that has advanced greatly, sometimes with the placement of as many as 256 electrodes. Magnetoencephalography (MEG) is similar to EEG except that it measures magnetic fields using squibs placed on the scalp. EEG and MEG are both particularly useful for following the timing of events since they measure neuronal activity as it’s happening. You’ve probably heard of EEG in the context of observing brain waves.

Positron Emission Tomography (PET) and Magnetic Resonance Imaging (MRI) have also been widely used for a while. Functional MRI (fMRI), invented in 1990, gives a 3D image of brain activity by detecting small changes in the blood flow that follow the onset of that brain activity. But while fMRI gives a good full brain view of where activity happened it lags neural activity by around 1 or 2 seconds and so it doesn’t offer the precise timing you get with EEG or MEG.

Along with electrodes in the area of brain stimulation are Transcranial Magnetic Stimulation (TMS) and optogenetics. TMS uses electromagnetic induction to cause a current across neuron cell membranes which can cause them to fire. Optogenetics causes neurons to fire by stimulating them with light, usually from a laser.

Masking and Subliminal Priming

Back to consciousness. Imagine being able design an experiment where you can control what’s processed unconsciously and what’s processed consciously so that you can then use instruments to determine which neural pathways are used in the two cases. Masking is a tool that allows that level of control. An example of masking is to show an image for 33 milliseconds, but before and after showing it, show another image called a mask. You’ll be conscious of the mask image but not the middle one that was shown for only 33 milliseconds. That length of time is ideal, and the longer it is shown for, the greater the likelihood you’ll be conscious of it.

Masking and priming experiment.
Masking and priming experiment.

One example of such an experiment shows a 71 ms mask, then a numerical digit or the word for a number for 43 ms, then another 71 ms mask and then a second digit, this time for 200 ms. You won’t have processed the first number consciously but you’ll be asked to indicate if the second digit was less than or greater than 5 by raising either your left or right hand respectively. If the value of the first digit was close to the value of the second digit then you’ll be able to move your hand sooner.

Why? Because even though you weren’t conscious of the first digit, unconscious pathways in your brain involving the motor cortex will have been activated due to the the first digit. And even though you don’t know it, the processing going on has been observed using EEG and fMRI. This experiment is also called priming or subliminal priming, where the first digit primes the activity for the second one.

Attentional Blink

Another technique for creating conscious and unconscious processing in an experiment is to take advantage of the fact that there’s a limit on the number of things that can be attended to at the same time, you saturate consciousness. One way to demonstrate this is to show a sequence of numbers and in the middle, show two letters. You are told to watch for the letters. The first letter is easily remembered. However, if the second letter comes too soon after the first then you will not be aware of it at all. This is called attentional blink. Along with some tweaking, it allows you to study what happens in the brain when the letter is consciously perceived versus when it’s not.

These priming, masking, and attentional blink techniques have been so finely tuned that all sorts of experiments can be planned ahead of time where researchers can produce unconscious and conscious activity at will and then observe the resulting brain activity.

Observing Conscious Activity

EEG of conscious and unconscious brain activity.
EEG of conscious and unconscious brain activity.

An experiment that involved observing conscious activity  involving attentional blinkand eventually contributed to the ability to detect consciousness in coma patients. The experiment used EEG so that events could be observed as they were happening. A sequence of images of letters and words were shown to the subjects. They were asked to detect words in the sequence but were also shown images that had letters which they were to report on. The letters acted as a distraction, making them miss the word. This was the attentional blink. The experimenters tuned the parameters so that they could control when the subjects would consciously see the word and when they would be unconscious of it, it would be unseen.

The diagram shows the EEG results comparing brain activity when the word was seen versus when it was unseen. The activity at around 96 ms and 180 ms was pretty much the same for both. This is unconscious activity where early processing of the images was going on. But then around 276 ms, there began a big difference in activity between when the word was seen versus when the word was unseen. This continued right up to around 576 ms. This difference is the conscious processing.

This timing and activity is found to be common for conscious activity involving vision. Practically identical processing happens for around the first 300 ms in experiments where subjects report being unconscious or conscious of what’s being tested. However, for the experiments where subjects report being conscious of what’s being tested, starting around 300 ms there’s an avalanche of activity.

In Stanislas Dehaene’s book, Consciousness and the Brain: Deciphering how the brain codes our thoughts, he describes four signatures of conscious thought, i.e., the activity that is observed during this avalanche:

  1. a sudden ignition of activity in the upper back area of the brain where sensory processing happens (the parietal region) and the front part of the brain’s frontal lobe (the prefrontal cortex) which is implicated in decision making, short-term memory, planning and other high level activity,
  2. a P3 wave observed using EEG that sweeps over the parietal region and the prefrontal cortex,
  3. a late and sudden burst of high-frequency oscillations, and
  4. a massive synchronization of electromagnetic signals across the entire cortex — the wrinkled outer layer of the brain.

These then are signatures of consciousness and examining what’s going on in the brain during this time may someday lead to understanding exactly how consciousness works. In the meantime, this research has lead to a consciousness detector.

Detecting Consciousness In Coma Patients

In his book, Dahaene describes how he and his colleagues made use of this research to detect consciousness or the lack thereof in coma patients. To make it cheap, they used EEG, available to many intensive care units. They tested for the P3 wave, the 2nd signature of consciousness.

They play four identical sounds followed by a fifth deviant one: beep, beep, beep, beep, boop. The deviant one triggers a P3 wave. Unfortunately the auditory cortex also produces an unconscious mismatch response, called MMN, which also results in a P3 wave. To make up for this, they play the repeating four beeps and the deviant boop for a while and then suddenly play five beeps without the deviant. Without the deviant, the unconscious mismatch response doesn’t activate but conscious processing notices that there was no deviant and the P3 wave still occurs. A patient who wasn’t conscious would not produce the P3 wave.

Their test identified different patients as unconscious or conscious and the ones that showed consciousness regained partial or full consciousness within days. Subsequent use of the test even saved a life. Doctors had a patient whom they were ready to give up on when this detection technique convinced them to wait a while longer. They did so and the patient eventually recovered fully.

So the next time someone tells you that we don’t know what consciousness is and that it’s some mystical, unknowable thing, tell them that there is actual scientific research into consciousness that has already produced beneficial results, even if the field is still in its infancy.

43 thoughts on “The Real Science (Not Armchair Science) Of Consciousness

      1. Penrose’s version has seen zero evidence, and his pop science book “The Emperor’s New Mind: Concerning Computers, Minds, and The Laws of Physics” (1989) hasn’t held up very well over time. Certainly it’s fascinating, and I admire Penrose’s putting his reputation on the line back then, but I’d very much suggest looking at newer research. There just, afaik, hasn’t been any supporting evidence forthcoming, which one would expect after 30 years since it hit popular media.

        1. Newer research supports the idea somewhat. When analyzing the problem of choice, there is a difference between classical probability and quantum probability distribution in e.g. choosing whether you’d like to have vanilla or chocolate ice cream. The data supports the idea that the choice is not made according to classical priming, but it’s made up on the spot like in quantum mechanics.

          That still leaves the question whether the brain is operating on QM or just implements a similar collapse of a wave function mechanism that produces probabilities that look very much like QM.

  1. This article would benefit from a rigorous definition of consciousness. The subjective test that’s described doesn’t test for consciousness, but rather the recollection of consciousness.
    For example, I do not recall what I had for lunch yesterday. If a researcher used this test to study my lunch experience, they’d conclude that the lunch experience was unconscious. But by most understandings of the word, that would be clearly incorrect. Whether I chose a restaurant, made a sandwich, or opted for brunch instead, there was definitely conscious thought involved.

    1. >doesn’t test for consciousness, but rather the recollection of consciousness.

      Same thing. You’re not conscious of thoughts that happened ten seconds ago because they’re not retained in memory. Your consciousness only spans that amount which is presently remembered, which is saying, consciousness is the recollection of thought. Things that simply pass through the mind without memory being involved cannot be consciously perceived because you forget them instantly.

      1. True, but let’s return to my lunch example. If the researcher had asked me about my lunch shortly after I ate it, I’d be able to tell them all about it – what I had, why I chose it, how it tasted. They would then conclude that the lunch was a conscious experience. It seems odd that a single event can be categorized as both conscious and unconscious based solely on when you sample the memory of it.

        Let’s stretch the concept further: I have no memory at all of Saturday, October 23, 2021. Was I unconscious that whole day?

        Or consider people with a short-term memory impairment. Are they never conscious?

        (I recognize that we’ve left the point of this article behind, but consciousness is very fun to think about.)

          1. That’s not exactly what the data shows, because the studies you’re thinking about didn’t distinguish between priming for a decision and the decision itself. In other words, it’s like observing a hand that is preparing to flip a coin.

        1. >Let’s stretch the concept further: I have no memory at all of Saturday, October 23, 2021. Was I unconscious that whole day?

          You are unconscious of that day right now, because you have no memory of it. Whether you were conscious then is a different question entirely that cannot be answered in your present state.

          In other words, you may forget that you were conscious, but that does not mean you were not conscious – just that you forgot about it.

        2. there’s various types of memory, which has neurological science as well as questionnaires behind it. Short-term and long-term memories are quite distinct, as there are differences between ordinary vs traumatic memories, etc. You criticize the lack of definition for consciousness by using examples that neglect to define what you mean by “memories”. Actually, I might have accepted your original criticism, but then you had to make up these ridiculous examples to prove the error, and I think that was quite a mis-step. Stop doing that!!!

    2. all of this field has huge definition problems. you can produce an experiment like one described in this article…try different mechanisms to prime the subject, and then measure their performance on a recognition task. and it might generate nice, clear, unambiguous data, separating the participants into two groups based on how they were primed. it’s quantitatively a success, but then, what do you call the two processes that you’ve revealed through this data? is one conscious, one unconscious? we can speculate a great deal, and with MRI or so on we may even be able to ground that speculation. but at the end of the day we still have to name the phenomenon and that name can’t hope to capture the complexity of the human participants.

      and we’re left with that struggle even after we’ve had the successful experiment!

    3. defining consciousness is utterly difficult. Where does it start ?

      Is a plant conscious ? most would say no. An ant ? same. A swarm of ants ?
      Plants, for example, have elaborate ways of communication:
      – From plant to insects (like some flowers modulating the electric fields around them to warn bees that the nectar is available or already gone)
      – Plant to plant: trees communicating through their roots in a complex way, and even exchanging nutrients to feed the other plants they are in contact with.
      – Plants to symbiotic organisms.

      And what about bacteria ? like when tightly woven together with extracellular matrix, they can exchange chemical signalling. Or even *directly* send to each other genetic material (!!!) through a tubules networks, even interspecies !
      Like a gene that codes for resistance to an antibiotic that spreads over a colony of several species of bacteria.

      Sooo. where does it start ? the most basic apparent level of consciousness is to avoid conditions that are not good (for the organisms who can move) or threats.
      And what about a robot whose *behaviour* imitating life to a level that one cannot tell if it´s a robot or a genuine biological organism ? is it conscious ? No, it´s programmed to act and answer to stimuli. What if it´s driven by A.I. ?

      Check the works of Daniel Dennett on this subject, it´s damn interesting.

    4. Now if we approach the experiment from the other side: lets train a simple neural network with some sounds (series of character would be easier and equally valid). We train it with a large set of examples to predict what the next thing will be that happens by optimizing the distance between input and output. Then you give it a pattern that it has never heard before. If the output now shows large difference for a certain more unusual pattern as compared to a more common pattern we have detected conciousness in the neural network. Indeed the NN has an active model predicting what will happen based on what already happened and can observe when its predictions are off.
      Jef Hawkins “on intelligence” gives a very nice example explaining that you would be quite surprised if while you were away somebody would have changed the weight of your front door considerably. When you open the door unconsiously you notice that it didnt react the way you anticipated and you get into a high alert state noting that something is weird.

      I always thought that conciousness was a special model of ourselves amongst the many models we hold in our mind describing other things and thought that you needed at least a certain level of complexity in a NN before it could occur. But with the above definition even a very simple NN would be concious.

      So far for my armchair thoughts

    1. What about the stuff that you forgot about, that comes back to mind when prodded? You’ve “forgotten” all kinds of stuff about your childhood that could all come rushing back to you when you see an old picture or smell a familiar smell. Where is this stuff stored so that it is so utterly forgotten and yet so easily recalled?

      1. What about it? Consciousness is about what memory you’re processing right now, and whether that is a self-referential memory or just some once-through reaction that vanishes as soon as it’s done leaving no echoes of itself in the mind.

      1. I don’t think a passive record qualifies as “remembering” in the same sense of activity as a mind does. Furthermore, a program can’t exactly constitute a mind (see: chinese room problem).

    1. Thanks! I don’t get as much to write as I used to but every now and then I have an idea that I just have to write about. It’s good to see you’re still here and going strong!

  2. > It was taboo to even use the C-word until the 1980s when researchers decided that subjective results were okay.

    I’m sure that subjective results were perfectly fine for most research around the globe for the last few thousands of years. Perhaps you are thinking about a very specific group of researchers, for example middle-aged white men wearing pants and speaking English?

    1. The vast majority of global scientific research is in English, even when researchers aren’t fluent speakers or speakers at all. English has come to be the international standard for science, just as in earlier times Latin was for Law and medicine. The fact you don’t seem to realize this shows you don’t know what you’re talking about. (Plus you seem to have missed the joke about “using the C-word”) Please, just don’t comment like this. I believe strongly in raising the numbers of females and those of non-binary sexual identification in science, but just throwing around terms like “white men wearing pants” doesn’t help. It just doesn’t.

  3. > An experiment that involved observing conscious activity involving attentional blinkand eventually contributed
    An experiment that involved observing conscious activity involving attentional blink eventually contributed
    (I think and note ” ” -> ” “)

    Interesting topic but I ‘fear’ the time when new findings in this field get abused by ads… :-/

  4. I think the word “unconscious” the absolute wrong word. If a group of people each have a specialty that the others are not aware of it does not mean that the expertise of others is unconscious. The word “subconscious” should be used instead because your brain has more than one consciousness but not all of them are in communication with one another however that does not mean they are not conscious which pure assumption is a huge over step.

    1. That’s even worse. “Subconscious” is extremely ambiguous and invokes a load of Freudian nonsense.

      You’re either conscious of something or you’re not. So brain processes are either conscious or nonconscious. That’s all we need.

  5. I remember reading about a technique they nicknamed “Zap-Zip” in Scientific American. It was based on EEG entropy, which is already measured in commercial EEG machines for evaluating deepness of anaesthesia. It also produced useful predictions in comatose patients.

  6. Just one niggle with the article: The device used in magnetoencephalography is actually a SQUID (Superconducting Quantum Interference Detector), not a squib (a small explosive device unsuitable for precision neurological examinations.)

    1. Good catch! I’m familiar with both of them but I swear I read squib in whatever article I read about using MEGs in brain research. In either case, the brain fart is ultimately mine.

  7. But what if all you have to go on is what a person says they are experiencing, a subjective observation? That doesn’t sound very scientific.

    And yet, psychologists and especially sociologists, still pretend.

  8. What about people who had been in a coma for years and came out of it and claimed to have experienced everything around them while unable to do anything.

    I wonder what that detection method of consiousness would show.
    just curious

    what if someone is in a coma for years and they try this detection method and find that it is still there what do they do??
    what can they do?? keep caring for the person of course but why is it stuck in there and why can’t it get out.

    i find all this so fascinating :)

    1. For the purposes of this article (and the experiments) consciousness is defined as what the person reports that they’re aware of. The hope is that by observing the brain’s activity following that awareness, after first subtracting the activity that’s present both in tests when they’re aware and unaware, that theories of consciousness can be better made from knowing that brain activity. It’s a scientific approach to consciousness, one based on observation and experimentation.

  9. Technically science has been studying subjective questions via self-report for a long time. For instance, “how much does this hurt?”, and “count back from 100 while you breath this”.

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