Axons & Axioms, Episode 3: Matrix Revolutions

Welcome to the next edition of Axons & Axioms, a podcast on philosophy and cognitive neuroscience by myself and Derek Leben (Assistant Professor in Philosophy at University of Pittsburgh, Johnstown). Today we delve deep into the realm science fiction to ask what “reality” really means. As always, since Derek contributed equally to this post, as well as to the podcast, from here on out I’m going to refer to myself in the third person to indicate the joint contribution

Brain in a vat

In this episode we ask a provocative question: Given what we know about the brain, is it possible that we live in “The Matrix?”

Now for those of you who’ve never seen the science fiction hit “The Matrix” (1999), stop reading right now and go watch it. We’re pretty much going to spoil the first half of the movie for you in the next paragraph.

Okay… seriously… you’ve been warned.

In “The Matrix”, Neo (Keanu Reeves) believes he lives in a city in 1999, he goes out for noodles, he is constantly late for work, and he secretly makes money as a computer hacker. However, he soon discovers that almost everything he believes about this world is false- it’s all a computer simulation in his mind. In reality, he has been floating in a tub his entire life with fake experiences being pumped into his brain.

This movie sparked a lot of interesting questions for audiences. What about our world? How likely is it that we’re in the same situation as Neo?

Descartes' Dilemma

Philosophers have always been concerned about whether our perceptions are getting at the ‘real’ world, but the idea that we might be massively deceived about our most basic beliefs was taken to extremes by the French philosopher Rene Descartes.

Descartes argued that you can’t tell the difference between your experiences right now and fake experiences when you’re dreaming , or even worse, if you are being deceived by an ‘evil demon’ who is keeping you in a very vivid artificial dream. He suggests that if you can’t tell the difference between one and the other, then you don’t really know anything about your reality. Descartes went on to try to show that we can actually discover things about our reality by starting from something that has no alternative explanation (our own thoughts). Hence his eponymous slogan “I think therefore I am.” The only thing I can really be absolutely certain of is that I am a thinking being. Everything else is suspicious.

Our interest is whether this ‘thought experiment’ concocted by Descartes is more than just a conceivable possibility: could we actually simulate an entire false reality for somebody’s brain? If so, then this makes Descartes’ argument even stronger.

Brain in a vat ... in our heads?

This question about the reliability of our perceptions of the world has also interested psychologists since its inception. William James dedicated an entire chapter to “The Perception of Reality” in his Principles of Psychology. It turns out that we are not, in fact, the best judges of the “real” world around us.

Tomes of empirical research in psychology and neuroscience have demonstrated that our “perceived” reality is actually more of a simulation of the world rather than a reconstruction of the world seen through our senses. Take for example, the blind spot. We are all walking around with a pretty big hole in our vision. This comes from the fact that the optic nerve takes up a big chunk of valuable real estate in your retina. You can’t actually “see” any light that gets projected to this part of the retina, which sits pretty much in the center of your field of view.

But unless you do some clever tricks, you never actually really “see”, or to be more accurate you do not “perceive”, this blind spot in our eyes. Why? Because when it’s processing the visual image of the world, your brain fills in that gap based on all the other information it sees.

Now there are tons of examples of this kind of your perception not matching your senses.

• You can’t see color in your peripheral vision.
• You can’t easily tickle yourself.
• You see a moving object where it will be ~200ms in the future.
• You’ll see contours that are not present.

In fact, entire fields of study are dedicated to understanding these strange perceptual illusions. But the one common denominator is that our perceptions of the world are not strict reconstructions of the world as seen from our senses. Instead, it appears that we see the world as we expect to see it and use the sense to either validate this model or update it when it’s incorrect.

This makes sense when you consider how difficult of a problem perception is. Konrad Kording recently pointed out that the human brain processes as many bits of data in 30 seconds as the Hubble Space Telescope has produced in its entire lifetime. Most of this processing involves the senses. So from a computational perspective it’s either deal with processing a massive tsunami of information coming in from the sensory organs all at once or simply occasionally check on the senses to make sure your internal simulation of the world makes sense. Which do you think is easier?

Neuroscience Essential Reads

How the Brain Learns to Perform Quickly Without Overthinking

The Upcoming Solar Eclipse Is a Natural Wonder

Okay, what does this have to do with our original question of reality? Well Tim argues that, if all our brains are doing is using sensory information to validate an internal model of the outside world, then as long as those expectations are being met in the right way, it would be theoretically feasible to simulate them. Our brains are already sitting in a vat of fluids (just in our heads) connected to biological wires that feed sensory information and drive our muscles. Is it really that far fetched that these could be replaced with artificial wires and sensors? In fact, we’re already starting to do that in neuroscience right now.

Are we in a vat already living in a simulated world? We may never really know for sure. But our (possibly-simulated-discussion) goes over this from both the philosophical and cognitive neuroscience perspectives. Check out the full argument on the nature of reality in the podcast titled “Matrix Revolutions.”

* We have decided to stop imbedding the audio in these posts because of the annoying autoplay feature in the media player. Please follow the link to the host site or check us out on iTunes.

** Please note that we have moved hosts for the podcast. All old and new episodes can be found on The Media Page at www.cognitiveaxon.com.

*** Teaser image courtesy of Wikipedia