Blindsight

[grunion]

Randi's Commentary today, referring to purportedly "blind" people who can distinguish color, reminded me of an item I saw in the paper the other day describing a study by a Rice University scientist who demonstrated that subjects who were temporarily blinded through disruption of their visual cortex were still able to distinguish between red and green dots and determine the correct orientation of a line a statistically significant percentage of the time.

The conclusions that the study (briefly described at http://msnbc.msn.com/id/9879390/) drew, though disputed by many, were that the brain has alternate visual sensory paths than those that are presently understood, a "second pathway for experiencing sight." Some of the subjects were "just guessing" while others "had a feeling" about the object. The researcher, Tony Ro, apparently places a lot of importance in the power of the unconsious mind in perception.

I thought it was interesting, and am glad that it is published in a scientific journal, so peer review and follow-up studies can take place. I am still reserving judgement until the scientific community-at-large weighs in. I also wonder if this sort of perception would qualify as "paranomal" and thus be eligible for the JREF prize.

[drkitten]

I thought it was interesting, and am glad that it is published in a scientific journal, so peer review and follow-up studies can take place. I am still reserving judgement until the scientific community-at-large weighs in. I also wonder if this sort of perception would qualify as "paranomal" and thus be eligible for the JREF prize.

Well, "blindsight" in general is well-established scientifically. I'm not specifically familiar with the new results you cite, but there's a lot of other, related, experiments on perception in people with damaged visual cortexes.

And no, I doubt Randi would consider it paranormal in any way, so it wouldn't qualify for the million.

[Soapy Sam]

No , it's not paranormal, because there is a degree of understanding about how it works. It seems that information can be processed by more than one area of the brain. The output will be qualitatively different.
In simplistic terms, if you wire the output from a video player to (say) a stereo soundsystem, you still get an output. It would be meaningless noise.
But there is every probability the same input signal, processed by the stereo will yield the same meaningless noise each time. After playing a few different video clips, you will learn to identify which clip produces which noise. You can actually "hear them apart". The effect is repeatable.

It appears similar effects occur in the brain, becoming apparent only if one normal sensory channel is blocked.
Synaesthesia is a related phenomenon- signals are processed in the "wrong" parts of the brain, letting people "smell" colours or even see numbers as having innate colours. Wierd, but true.

ETA- I suspect this effect actually happens all the time and is simply ignored by the conscious mind which prefers to work through "normal" channels. At a subconscious level, I think we all hear with our eyes etc all the time. I think it's where a lot of unexplained hunches come from and where many supposedly "symbolic" dream images originate.
I'd stress this is purest supposition on my part.

[grunion]

No , it's not paranormal, because there is a degree of understanding about how it works....
It appears similar effects occur in the brain, becoming apparent only if one normal sensory channel is blocked.
I assume that by "normal sensory channel is blocked" you mean in this case that the eyes are fully functional but the brain receptors are defective in some way. Some one with no eyes (or is actually, effectively blindfolded) would not be able to process visual input through the use of touch or smell, for example, but a blind person (who suffers blindness due to dysfunction of the visual cortex, not by dysfunction of the eyes or optic nerves) could indeed develop and refine this faculty in order to distinguish between colors and shapes? Or does it work both ways, therefore giving credence to some of the outrageous claims we hear about people able to "see" with their fingers (or with their ears, as you posit)?

[Jeff Corey]

Ask Kilik, or Likil or some other palindope.

[Rolfe]

I watched a very detailed TV programme about blindsight last year. If I remember correctly, it describes a more primitive method of visual processing essentially dedicated to the avoidance reflex.

They showed a man with a destroyed visual cortex who could duck when tree branches were across his path, and reliably tell which direction a dot on a computer screen was moving - but he couldn't see anything that was stationary. He functioned quite well, because he was able to make quite good use of the ability as well as using a cane and so on.

Then they showed another man with a perfect visual cortex, but the blindsight part of the brain damaged. He was much less functional because he couldn't tell the significance or the meaning of anything he saw. He was institutionalised.

Interesting stuff.

Rolfe.

[PatKelley]

Saw another report on a fellow who still had marginal better-than-chance expression recognition but was otherwise blind. He could tell if someone in the room was sad, but not if someone was in the room or not. Had to do with the face recognition section of the brain. Look up "face blindness" and see what that delves up. The brain is a complicated wired-up doohickey.

It's not really a separate pathway so much as like a 3-D graphics card for your computer: Handles the complicated stuff that needs doing in a hurry (face recognition) but not much else.