IN connection with Reversible Computation and Experience, Hal
Finney mentions a post of his from Sept. 1997
in which he examines the issue of memory retention versus
experience. Actually, that's how *I* would summarize it.
Here is what he really said:
"You could envision a neural simulation on a Time Warp machine. It
assume some default pattern of incoming impulses into the part of
brain being simulated by some processor. Then, if the actual data
arrived was different from what had been assumed, it would roll back
state and handle the data as needed. If it turned out that the
model for incoming data was reasonable accurate much of the time,
could be a very efficient way to simulate the brain on a network.
"The interesting question this raises is whether there would be
conscious perception by the simulated brain of the "paths not
Frequently, part of the brain moves forward in time assuming
pattern of outside impulses, only to find out that the actual
was different from what was assumed, so that it resets its state to
it was in the past and proceeds forward to process the actual data.
there are transient brain states being computed which do not
to the actual brain states which the simulation eventually
"We assume that the (simulated) neural activity is what gives rise
consciousness. Therefore it might be that the simulated "wrong"
activity could give rise to a consciousness which does not match
"true" consciousness being determined by the simulation. This
consciousness would have no way of interacting with the outside
of revealing its existence through any overt behavior. The person
simulated would steadfastly deny that he had any unusual
or sensations due to the time warp simulation (because all the
ones would get rolled back and erased). Yet we have reason to
that he is wrong, by the principle which identifies mental states
(simulated) brain states.
"This could be thought of as a case where behavior cannot reveal
I think that's exactly correct. To me it's also an illustration
of the difference between memory acquisition and experience. One
can today have the latter without the former: sleeping pills
containing midazolam prevent short-term memory from becoming
permanent). In Hal's case, the duration of each piece of
experience is so brief that the experiencer cannot even begin
to articulate his or her experience.
I stress the primacy of experience, and not the memories of it that
I carry into the indefinite future. Though obviously important,
memories might be artificial, whereas experience, by definition,
is always genuine.
But Hal's post has a disturbing implication. His description of
a time-warp brain isn't so different from what we now know about
real brains! Certain experiments indicate that your brain does
take several paths at once, and you only remember the "winner".
I recall an experiment in which they somehow got the subject to
to reliably specify the point at which a certain image or idea
occurred to him. The trouble was, that by this time the
information that the subject had received was still ambiguous.
(For example, the subject might have heard either "bear" or "bare"
and couldn't yet have formed the proper image.) Evidently, memories
of the "other paths" were discarded by the brain.
So if I stick to my guns here, the implication is that I may be
conscious (in the long run) of only a small part of my experience.
Very confusing conclusion!
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