On Saturday, January 5, 2013 10:43:32 AM UTC-5, rclough wrote:
>
>
> Subjective states can somehow be extracted from brains via a computer.
>
No, they can't.
>
> The ingenius folks who were miraculously able to extract an image from the
> brain
> that we saw recently
>
>
> http://gizmodo.com/5843117/scientists-reconstruct-video-clips-from-brain-activity
>
>
> somehow did it entirely through computation. How was that possible?
>
By passing off a weak Bayesian regression analysis as a terrific
consciousness breakthrough. Look again at the image comparisons. There is
nothing being reconstructed, there is only the visual noise of many
superimposed shapes which least dis-resembles the test image. It's not even
stage magic, it's just a search engine.
>
> There are at least two imaginable theories, neither of which I can explain
> step by step:
>
What they did was take lots of images and correlate patterns in the V1
region of the brain with those that corresponded V1 patterns in others who
had viewed the known images. It's statistical guesswork and it is complete
crap.
"The computer analyzed 18 million seconds of random YouTube video, building
a database of potential brain activity for each clip. From all these
videos, the software picked the one hundred clips that caused a brain
activity more similar to the ones the subject watched, combining them into
one final movie"
Crick and Koch found in their 1995 study that
"The conscious visual representation is likely to be distributed over more
> than one area of the cerebral cortex and possibly over certain subcortical
> structures as well. We have argued (Crick and Koch, 1995a) that in
> primates, contrary to most received opinion, it is not located in cortical
> area V1 (also called the striate cortex or area 17). Some of the
> experimental evidence in support of this hypothesis is outlined below. This
> is not to say that what goes on in V1 is not important, and indeed may be
> crucial, for most forms of vivid visual awareness. What we suggest is that
> the neural activity there is not directly correlated with what is seen."
>
http://www.klab.caltech.edu/~koch/crick-koch-cc-97.html
What was found in their study, through experiments which isolated the
effects in the brain which are related to looking (i.e. directing your
eyeballs to move around) from those related to seeing (the appearance of
images, colors, etc) is that the activity in the V1 is exactly the same
whether the person sees anything or not.
What the visual reconstruction is based on is the activity in the
occipitotemporal visual cortex. (downstream of V1
http://www.sciencedirect.com/science/article/pii/S0079612305490196)
"Here we present a new motion-energy [10,
> 11] encoding model that largely overcomes this limitation.
> The model describes fast visual information and slow hemodynamics
> by separate components. We recorded BOLD
> signals in occipitotemporal visual cortex of human subjects
> who watched natural movies and fit the model separately
> to individual voxels."
> https://sites.google.com/site/gallantlabucb/publications/nishimoto-et-al-2011
>
So what they did is analogous to tracing the rectangle pattern that your
eyes make when generally tracing the contrast boundary of a door-like image
and then comparing that pattern to patterns made by other people's eyes
tracing the known images of doors. It's really no closer to any direct
access to your interior state than any data-mining advertiser gets by
chasing after your web history to determine that you might buy prostate
vitamins if you are watching a Rolling Stones YouTube.
a) Computers are themselves conscious (which can neither be proven nor
> disproven)
> and are therefore capable of perception.
>
Nothing can be considered conscious unless it has the capacity to act in
its own interest. Computers, by virtue of their perpetual servitude to
human will, are not conscious.
>
> or
>
> 2) The flesh of the brain is simultaneously objective and subjective.
> Thus an ordinary (by which I mean not conscious) computer can work on
> it
> objectively yet produce a subjective image by some manipulation of the
> flesh
> of the brain. One perhaps might call this "milking" of the brain.
>
The flesh of the brain is indeed simultaneously objective and subjective
(as are all living cells and perhaps all molecules and atoms), but the
noise comparisons being done in this experiment aren't milking anything but
the hype machine of pop-sci neuro-fluff. It is cool that they are able to
refine the matching of patterns in the brain to patterns which can be
identify computationally, but without the expectation of a visual image
corresponding to these patterns in the first place, it is meaningless as
far as understanding consciousness. What it does do though is provide a new
hunger for invasive neurological technologies to analyze the behavior of
your brain a
