Scientists Settle centuries-old debate on perception

http://www.physorg.com/news/2011-04-scientists-centuries-old-debate-perception.html

by dhernandez5622 • 15 years ago

96 12 15 years ago

dhs• 15 years ago

I find this very interesting. If I understand this correctly, the suggestions are: (1) the "slate" is relatively "blank" to start with (abstract objects, for instance, do not "exist", in the sense that they are inheritable); (2) a generic ability to abstract could very well be inheritable; (3) the "slate" remains in a "writeable" state longer than previously expected - the right "nurture" can enable the unfolding of potential abilities even relatively late in life (abstract objects can become "real", even though they don't "exist", in the sense that they can become "meaningful").

strayer• 15 years ago

The physorg article mixes up, at first, the nature/nurture question and the cross-modality of perception question (whether internal representations good for tactile perception are also good for visual perception). Those are very different fundamental questions.

nitrogen2• 15 years ago

It sounds like they didn't actually test Molyneux's question at all, or prove anything about perception. It sounds more like an additional data point to nudge our understanding of the brain toward greater plasticity.

JacobAldridge• 15 years ago

Molyneux's question: Could a man, blind since birth who can tell the difference in shapes only by feel, given suddenly the ability to see be able to distinguish by sight those shapes?

Pawan Sinha's test: They took five people who had been blind since birth, performed the surgery to restore the sight, and performed the test which indicated that they could connect the tactile experience with a visual one no better than chance.

It's a very small sample size, to be sure, but to claim "they didn't actually test Molyneux's question at all"? Not sure which part of the article you missed.

nitrogen2• 15 years ago

The article says the subjects were given similarly-shaped objects, not a sphere and a cube (as noted by comments on the article). This gives the impression that the question whether very rough differences in shape, e.g. sphere vs. cube, can be distinguished immediately after sight is restored is still unanswered.

aycangulez• 15 years ago

These results were expected by neuroscientists. Different senses are encoded differently in the brain. So, the subjects were unable to link them at first. The surprising thing here is the speed the association between tactile and visual encodings happened, and the article makes that clear.

mbateman• 15 years ago

Here's the classic reference to the problem in Locke (which vindicates Locke's speculative answer here):

http://books.google.com/books?id=vjYIAAAAQAAJ&dq=essay%2...

> To which purpose I shall here insert a problem of that very ingenious and studious promoter of real knowledge, the learned and worthy Mr. Molineux, which he was pleased to send me in a letter some months since; and it is this: "Suppose a man born blind, and now adult, and taught by his touch to distinguish between a cube and a sphere of the same metal, and nighly of the same bigness, so as to tell, when he felt one and the other, which is the cube which the sphere. Suppose then the cube and sphere placed on a table, and the blind man made to see; quaere, Whether by his sight, before he touched them, he could now distinguish, and tell, which is the globe, which the cube?" To which the acute and judicious proposer answers: "Not. For though he has obtained the experience of, how a globe, how a cube, affects his touch; yet he has not yet attained the experience, that what affects his touch so or so, must affect his sight so or so; or that a protuberant angle in the cube, that pressed his hand unequally, shall appear to his eye as it does in the cube." I agree with this thinking gentleman, whom I am proud to call my friend, in his answer to this his problem; and am of opinion, that the blind man, at first sight, would not be able, with certainty, to say, which was the globe, which the cube, whilst he only saw them; though he could, unerringly, name them by his touch, and certainly distinguish them by the difference of their figures felt.

perlgeek3• 15 years ago

Did I miss the link to the original puplication, or did they actually fail to include it?

http://www.nature.com/neuro/journal/vaop/ncurrent/full/nn.27...

I find a study with 5 subjects a bit sparse, but I guess they are quite hard to come by...

jerf• 15 years ago

Why would you need more than 5? This isn't a drug trial trying to pick up some subtle difference in results between taking a drug and not taking a drug. Is it really plausible that a theoretical person born blind and sighted later in fact can distinguish between the two but we just happened to get unlucky to find the five dunces in the world who can't?

Based on what we already know about how the brain works (aka "the prior probabilities") the chances of such an outcome are pretty much insignificant, far lower than a naive sample-based argument that ignores what we already know would show.

perlgeek3• 15 years ago

> Why would you need more than 5?

because humans are quite diverse

> Is it really plausible that a theoretical person born blind and sighted later in fact can distinguish between the two but we just happened to get unlucky to find the five dunces in the world who can't?

We don't know which percentage of blind people can distinguish objects by sight once they start to see. We don't know if it's all-or-nothing or not.

If half of blinds can, there's still a 3% chance to get the published results from five subjects. If it's 30%, the chances grow to 17%.

Scientists Settle centuries-old debate on perception

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