TELEPATHY 83
they could also get pictures instantaneously (whereas MRI machines
can take up to twenty minutes to produce each picture).
Eventually, they theorize, taking an MRI photo could be as easy as
taking a picture with a digital camera. (There are stumbling blocks,
however. One problem is that the subject and the machine have to be
shielded from stray magnetic fields from the outside.)
If handheld MRI machines become a reality, they might be coupled to a tiny computer, which in turn could be loaded with the software capable of decoding certain key phrases, words, or sentences.
Such a device would never be as sophisticated as the telepathic devices
found in science fiction, but it could come close.
THE BRAIN AS A NEURAL
NETWORK
But will some futuristic MRI machine one day be able to read precise
thoughts, word for word, image for image, as a true telepath could?
This is not so clear. Some have argued that MRI machines will be able
to decipher only vague outlines of our thoughts, because the brain is
not really a computer at all. In a digital computer, computation is localized and obeys a very rigid set of rules. A digital computer obeys the
laws of a "Turing machine," a machine that contains a central processing unit (CPU), inputs, and outputs. A central processor (e.g., the Pentium chip) performs a definite set of manipulations of the input and
produces an output, and "thinking" is therefore localized in the CPU.
Our brain, however, is not a digital computer. Our brain has no
Pentium chip, no CPU, no Windows operating system, and no subroutines. If you remove a single transistor in the CPU of a computer, you
are likely to cripple it. But there are recorded cases in which half the
human brain can be missing, yet the remaining half of the brain takes
over.
The human brain is actually more like a learning machine, a "neural network," that constantly rewires itself after learning a new task.
MRI studies have confirmed that thoughts in the brain are not local-
they could also get pictures instantaneously (whereas MRI machines
can take up to twenty minutes to produce each picture).
Eventually, they theorize, taking an MRI photo could be as easy as
taking a picture with a digital camera. (There are stumbling blocks,
however. One problem is that the subject and the machine have to be
shielded from stray magnetic fields from the outside.)
If handheld MRI machines become a reality, they might be coupled to a tiny computer, which in turn could be loaded with the software capable of decoding certain key phrases, words, or sentences.
Such a device would never be as sophisticated as the telepathic devices
found in science fiction, but it could come close.
THE BRAIN AS A NEURAL
NETWORK
But will some futuristic MRI machine one day be able to read precise
thoughts, word for word, image for image, as a true telepath could?
This is not so clear. Some have argued that MRI machines will be able
to decipher only vague outlines of our thoughts, because the brain is
not really a computer at all. In a digital computer, computation is localized and obeys a very rigid set of rules. A digital computer obeys the
laws of a "Turing machine," a machine that contains a central processing unit (CPU), inputs, and outputs. A central processor (e.g., the Pentium chip) performs a definite set of manipulations of the input and
produces an output, and "thinking" is therefore localized in the CPU.
Our brain, however, is not a digital computer. Our brain has no
Pentium chip, no CPU, no Windows operating system, and no subroutines. If you remove a single transistor in the CPU of a computer, you
are likely to cripple it. But there are recorded cases in which half the
human brain can be missing, yet the remaining half of the brain takes
over.
The human brain is actually more like a learning machine, a "neural network," that constantly rewires itself after learning a new task.
MRI studies have confirmed that thoughts in the brain are not local-