A new theory proposes the anatomical basis for Subjective Experience. Discover how it works, and why it's less mysterious than it seems.
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Transcript:
If you’ve ever had a psychedelic hallucination, you know that your subjective experience is constructed by your brain.
My own most vivid memory of that was my first time on mushrooms, appropriately, at Burning Man. My friend, who brought the mushrooms, her face appeared to be dotted with extra eyeballs, like twenty of them, all staring and blinking at me.
Obviously, my perception was an error. But the hallucination showed me something very important, not about the drug, but about my experience.
What I learned is that what I see, when I open my eyes, is not the real world. Rather, what is in my perception is actually a construction. A simulation, built by my brain.
Clearly, when my brain added all those extra eyeballs to my friend’s face, it was making some serious mistakes (I mean, of course). My perception of my friend’s face was clearly mis-constructed. But (and this is the part that blew MY mind) that also means that all of normal perception is likewise constructed.
My brain didn’t just build a weird experience for me on psilocybin.
It is always building my perception.
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I should probably quickly make a distinction between the words ‘perception’ and ‘sensation’. ‘Sensation’ is the neural signal. Some remote sensing neuron, whether in the skin or the nose, on the tongue or in the ear canal or wherever, that neuron is activated by some stimulus, and sends its signal to the brain. Sensation.
Once at the brain, that signal is DECODED by the relevant brain part, where its information may feed other brain processes like behavior.
Perception, by contrast, is this simulation I’m talking about, this CONSTRUCT. Perception is clearly informed by sensation, (at least during waking ours...), but as the mushroom trip showed me, the simulation isn’t always faithful in its reproduction.
And not all sensation ends up IN perception. For example: if you’re driving your car while having a conversation with your friend, (as long as the driving is going well), You’re probably experiencing more perception of the conversation than you are of the driving (even though the driving is the more dangerous part!) You’re wrapped up in that conversation, and the driving seems to be almost automatic?
However, your brain is receiving all kinds of sensation about the road. And it is using that sensation to motivate behavior: steering, using the turn signals, braking, etc. But neither the sensation nor the behavior is very well represented within perception. Perception instead includes mostly just the conversation.
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And don’t get me wrong; if the drive suddenly became problematic, then your perception would quickly shift over. You would suddenly become very aware of the road, and the conversation would disappear boop. Your brain tries to represent the most important things that are happening, right now, within subjective experience and it leaves a lot of the lesser information out.
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Your perception even intentionally leaves out the one thing that your eyes (and thus your brain) sees the most. Which is: your nose. Your nose is within your field of visual sensation, all the time. If you look, there it is. You can also see your eyelashes.
And if you wear glasses, you know they dominate your vision. But your experience generator tends to leave all that out. Most of the time, it’s as if your nose (and eyelashes and eyeglasses) aren’t there at all.
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So perception represents not everything that’s going on, but only what’s important to your brain, at any particular moment in time. And it isn’t even necessarily about what’s actually happening in the outside world.
For example, think about your Subjective Experience while you’re reading a fascinating novel.
Yes! You do perceive the words on the page: black letters on white paper, but... That perception tends to be a relatively unimportant part of your experience, just like the driving was. What’s really important about the experience of reading a novel, is what your imagination adds. You feel the character’s emotions, you see what the author describes. You add the qualities of color and texture and even taste and smell and pain to this inner movie you make in your head.
So, if we want to explain Subjective Experience, we also have to explain this inner movie, this mind’s eye. We need to find a mechanism in the brain (that will turn sensations into perceptions), plus, it needs to feature the fruits of our imagination. Not only reading a book, but also: having a daydream. Or solving problems in our heads, like making plans or imagining a conversation with my boss. All of these mental simulations end up as part of the bigger simulation of Experience.
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Also, Memory Recall seems to happen within subjective experience.
You perceive your memories. You can see the old views and you feel the old feels. You can even smell and taste your memories. All of these functions of perception, imagination, and memory are part of my Subjective Experience and have to be explained by the mechanism that creates it.
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And what about ‘Awareness’? Awareness and Subjective Experience seem to be roughly the same things, right? We say that we are ‘aware’ of things, once they have entered our Subjective Experience.
But consider baseball players. In today’s professional baseball, the pitches have gotten so fast that players can no longer rely on perceiving the throw. The batters are swinging, before they perceive the ball coming at them. So, are the players ‘aware’ of the ball, when they’re swinging? If you ask them, they say ‘no’. They haven’t seen it. As far as they’re concerned, they’re using the friggin’ force. They swing when it feels right, and trust that some part of their brain has made the right decision.
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What’s happening? It’s these parallel systems, sensation vs. perception, which work on different time scales. Sensation (whch, again, is the neural signal) can immediately drive behavior, within a couple hundred milliseconds. Including hitting a baseball. Perception, by contrast, is a slower system, which combines all the senses together.
Sensation can cause in the brain a cascade of neural processing. And that cascade of processing can lead quickly to behavior, but only eventually to perception.
And what we call awareness only seems to happen at this late perception stage.
Through careful experiments, scientists have shown that there is a substantial delay in our awareness of stimuli, not only from the outside world, but also, stimuli directly applied to the surface of our brains.
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Like many neurosurgeons, Dr. Benjamin Libet performed operations on wake open-brain patients. Why? because there’s little pain. And because it’s important to get the patient’s feedback, throughout the surgery. You never want to cut too deep. For that reason, Libet was able to perform some very interesting experiments (with consent) upon his patients.
LIbet stimulated part of a subject’s somatosensory cortex, which elicited a phantom perception in one of the subject’s limbs. Through careful timing, Libet found that there was approximately a half second between when he stimulated the brain region, and when the subject became aware of that stimulation. Which seems like a long time, because he was stimulating the actual brain.
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Now, Libet didn’t stop there. His surgical timing experiments led to even more famous timing experiments, that Libet conducted with ordinary subjects. These experiments have been replicated over and over, by scientists all around the world, with the same result which is: our awareness of what’s going on in our own MINDS always comes late.
In the experiment, Libet’s subjects were placed in front of a very precise clock, which could allow them to report (within millisecond accuracy), upon exactly when they made a simple motor decision: move a finger. These subjects also had electroencephalographs, (EEGs) on their scalps, detecting the brain activity associated with motor decisions. So Libet was able to compare the measured brain decision with the reported mind decision. And the mind decision was always late.
The brain makes choices, causing a neural cascade, at the end of which is the perception of mind. This thing which I feel as my ‘will’ (to move my finger), that thing is just a part of the construct of Subjective Experience.
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And think about the other components of what we call ‘mind’. We think in words, we imagine in images, in tastes and smells the kinds of qualities you expect to find in ordinary perception. our imaginations and our thought processes ECHO the way we exist in the physical world.
But that, of course, is NOT how our brains work. our brain regions don’t talk to each other in English, or in any other human language. our brain regions talk to each other (roughly speaking) in spike trains, nested within gamma waves. That’s like super morse code
