Scientists Settle centuries-old debate on perception(physorg.com)
physorg.com
Scientists Settle centuries-old debate on perception
http://www.physorg.com/news/2011-04-scientists-centuries-old-debate-perception.html
6 comments
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.
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.
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...
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...
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.
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.
> 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%.
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%.
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").
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.
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.
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.
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.
I was going to say the same thing. I'd really like to see what objects exactly they used.
I have a variation on the original question. Suppose someone blind has never touched a cube. However, he knows that a cube is an object with 6 sides of equal dimensions and 8 corners. Then his blindness is suddenly cured. If he sees a cube would he be able to associate it with the description of a cube that's already in his head?
I have a variation on the original question. Suppose someone blind has never touched a cube. However, he knows that a cube is an object with 6 sides of equal dimensions and 8 corners. Then his blindness is suddenly cured. If he sees a cube would he be able to associate it with the description of a cube that's already in his head?
> I was going to say the same thing. I'd really like to see what objects exactly they used.
They used 20 sets of shape pairs, some examples of which can be seen in the original publication:
http://www.nature.com/neuro/journal/vaop/ncurrent/full/nn.27...
They used 20 sets of shape pairs, some examples of which can be seen in the original publication:
http://www.nature.com/neuro/journal/vaop/ncurrent/full/nn.27...
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.