By Tanya Lewis via LiveScience
SAN DIEGO — The human mind effortlessly constructs the feeling of inhabiting a body, and now scientists are figuring out how the brain produces that experience.
Recent studies have shown that the brain incorporates information from multiple senses and the first-person visual perspective to create a sense of body ownership. But it’s still unclear how the brain perceives the body’s location in space.
In the study, which has not yet been published in a scientific journal, participants lay inside an MRI scanner while wearing a head-mounted display that showed a first-person camera view of another person’s body lying in a corner of the scanner room, with their head either parallel to a wall or perpendicular to it. Researchers from the Karolinska Institutet in Sweden repeatedly touched each participant with an object while simultaneously touching the body shown in the camera view. This gave participants the illusion that the body in the camera view belonged to them.
To heighten the illusion, the researchers used . . .
Whenever the discussion of a dualist vs materialist model of the mind comes up, one common point made to support the dualist position (that the mind is something other than or more than just the functioning of the brain) is that the brain may not be the origin of the mind, but rather is just the receiver. Often an explicit comparison is made to radios or televisions.
The brain as receiver hypothesis, however, is wholly inadequate to explain the relationship between the brain and the mind, as I will explain below.
As an example of the brain-receiver argument, David Eagleman writes in his book Incognito:
As an example, I’ll mention what I’ll call the “radio theory” of brains. Imagine that you are a Kalahari Bushman and that you stumble upon a transistor radio in the sand. You might pick it up, twiddle the knobs, and suddenly, to your surprise, hear voices streaming out of this strange little box. If you’re curious and scientifically minded, you might try to understand what is going on. You might pry off the back cover to discover a little nest of wires. Now let’s say you begin a careful, scientific study of what causes the voices. You notice that each time you pull out the green wire, the voices stop. When you put the wire back on its contact, the voices begin again. The same goes for the red wire. Yanking out the black wire causes the voices to get garbled, and removing the yellow wire reduces the volume to a whisper. You step carefully through all the combinations, and you come to a clear conclusion: the voices depend entirely on the integrity of the circuitry. Change the circuitry and you damage the voices.
He argues that the Bushman might falsely conclude that the wires in the radio produce the voices by some unknown mechanism, because he has no knowledge of electromagnetic radiation and radio technology.
This point also came up several times in the 600+ comments following my post on the Afterlife Debate. Commenter Luoge, for example, wrote:
“But the brain-as-mediator model has bot yet been ruled out. We can tamper with a TV set and modify its behaviour just as a neurosurgeon can do with a brain. We can shut down some, or all, of its functioning, and we can stimulate to show specific responses. And yet no neurologist is known to have thought that the TV studio was inside the TV set.”
There are two reasons to reject the brain-as-mediator model – it does not explain the intimate relationship between brain and mind, and (even if it could) it is entirely unnecessary.
To deal with the latter point first, I have used the example of the light-fairy. When I flip the light switch on my wall, the materialist model holds that I am closing a circuit, allowing electricity to flow through the wires in my wall to a specific appliance (such as a light fixture). That light fixture contains a light bulb which adds resistance to the circuit and uses the electrical energy to heat an element in order to produce light and heat.
One might hypothesize, however, that an invisible light fairy lives in my wall. When I flip the switch the fairy flies to the fixture where it draws energy from the electrical wires, and then creates light and heat that it causes to radiate from the bulb. The light bulb is not producing the light and heat, it is just a conduit for the light fairy’s light and heat.
There is no way you can prove that my light fairy does not exist. It is simply entirely unnecessary, and adds nothing to our understanding of reality. The physics of electrical circuits do a fine job of accounting for the behavior of the light switch and the light. There is no need to invoke light bulb dualism.
The same is true of the brain and the mind, the only difference being that both are a lot more complex.
More importantly, however, we have enough information to rule out the brain-as-receiver model unequivocally.
The examples often given of the radio or TV analogy are very telling. They refer to altering the quality of the reception, the volume, even changing the channel. But those are only the crudest analogies to the relationship between brain and mind.
A more accurate analogy would be this – can you alter the wiring of a TV in order to change the plot of a TV program? Can you change a sitcom into a drama? Can you change the dialogue of the characters? Can you stimulate one of the wires in the TV in order to make one of the on-screen characters twitch?
Well, that is what would be necessary in order for the analogy to hold.