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I have no expertise in this area, but how about patterns? Since we're already parsing so much text, why not take strings of legible text (with a minor visual di

I have no expertise in this area, but how about patterns? Since we're already parsing so much text, why not take strings of legible text (with a minor visual distortion), and strip a connecting word such as a preposition? The user is then prompted to enter the connecting word. Synonyms could be matched. For example: "I can't stand all ____ your lies" (of) or: "This is all too ____ for me to handle!" (much) Sure, some strings would be hard to solve, but I feel like I'd be improved over time. Plus, captchas already take a few tries to solve anyway. I suppose it may impose on foreigners though.

wvs 14y ago
Finding dropped words in coherent sentences is trivially easy given a large enough corpus of the language. Just looking at the occurrence probabilities of the surrounding words would be enough for most cases.
pjscott 14y ago
What stops captchabots from just brute-forcing it with common words? Or, if they wanted to get fancy, something like a Markov model of English text could really help narrow down the likely missing words.
monsterix 14y ago
Tweaking that a bit, I think Captchas really need to change. But not with cut-off of grammar, which can be probabilistically (brute-force) broken. One can instead start asking simple questions presented over an image. For example, "how many blue dots on this pattern?" or "what animal is this?"(with a photo of camel or something). That's certainly going to be more manageable for humans and prevent us from behaving more like bots, and them like us. Of course, until the bots evolve a little more to circumvent this. It is so true that one often meets destiny on the path taken to avoid it. TLDR; Use image based 'A for Apple, B for Boy' aka the 'Kindergarten training' to filter out bots from humans. Ask questions that are human, to figure out humans in other words.
IvoDankolov 14y ago
Well, surprisingly, that would only be as strong as doing OCR to get the words. Why is that? Well, if you deliberately remove words that are easy to put back into the sentence, it's an easy task not because we humans are incredible at "out of the box" thinking, but because one or two word choices are orders of magnitude more likely than all the rest. And when it comes to statistical guessing, computers are very good at that. Get a large enough corpus of the English language, and I can assure you that the probability distribution of the missing word, given that it's preceded by "I can't stand all" and followed by "your lies" is overwhelmingly in favor of "of". Calculating these conditional probabilities is not a very hard task to program at all, though it does require quite some computational power and memory for longer chains.
unreal37 14y ago
My Android already does this, guessing the next logical word as I'm typing. This solution to Captcha has already been broken by AI.
muyuu 14y ago
This is remarkably easy to crack. Much easier than captchas.
michaelt 14y ago
https://www.google.co.uk/search?q=%22I+cant+stand+all%22+%22your+lies%22 https://www.google.co.uk/search?q=%22I+cant+stand+all%22+%22... https://www.google.co.uk/search?q=%22This+is+all+too%22+%22for+me+to+handle%22 https://www.google.co.uk/search?q=%22This+is+all+too%22+%22f... Then pick the first search result where there is a single word between the segments.
- drinkzima 14y ago
  Wildcard operator pretty much solves this: https://www.google.co.uk/search?q=I+cant+stand+all+*+your+lies https://www.google.co.uk/search?q=I+cant+stand+all+*+your+li... https://www.google.com/search?sugexp=chrome,mod=11&sourceid=chrome&ie=UTF-8&q=%22This+is+all+too+*+for+me+to+handle%22 https://www.google.com/search?sugexp=chrome,mod=11&sourc...
dalke 14y ago
This is all too complex for me to handle! (And "strange", and "weird", and "crazy" and ...)

wvs 14y ago

Finding dropped words in coherent sentences is trivially easy given a large enough corpus of the language. Just looking at the occurrence probabilities of the surrounding words would be enough for most cases.

pjscott 14y ago

What stops captchabots from just brute-forcing it with common words? Or, if they wanted to get fancy, something like a Markov model of English text could really help narrow down the likely missing words.

monsterix 14y ago

Tweaking that a bit, I think Captchas really need to change. But not with cut-off of grammar, which can be probabilistically (brute-force) broken. One can instead start asking simple questions presented over an image. For example, "how many blue dots on this pattern?" or "what animal is this?"(with a photo of camel or something). That's certainly going to be more manageable for humans and prevent us from behaving more like bots, and them like us. Of course, until the bots evolve a little more to circumvent this. It is so true that one often meets destiny on the path taken to avoid it. TLDR; Use image based 'A for Apple, B for Boy' aka the 'Kindergarten training' to filter out bots from humans. Ask questions that are human, to figure out humans in other words.

IvoDankolov 14y ago

Well, surprisingly, that would only be as strong as doing OCR to get the words. Why is that? Well, if you deliberately remove words that are easy to put back into the sentence, it's an easy task not because we humans are incredible at "out of the box" thinking, but because one or two word choices are orders of magnitude more likely than all the rest. And when it comes to statistical guessing, computers are very good at that. Get a large enough corpus of the English language, and I can assure you that the probability distribution of the missing word, given that it's preceded by "I can't stand all" and followed by "your lies" is overwhelmingly in favor of "of". Calculating these conditional probabilities is not a very hard task to program at all, though it does require quite some computational power and memory for longer chains.

unreal37 14y ago

My Android already does this, guessing the next logical word as I'm typing. This solution to Captcha has already been broken by AI.

muyuu 14y ago

This is remarkably easy to crack. Much easier than captchas.

michaelt 14y ago

https://www.google.co.uk/search?q=%22I+cant+stand+all%22+%22your+lies%22 https://www.google.co.uk/search?q=%22I+cant+stand+all%22+%22... https://www.google.co.uk/search?q=%22This+is+all+too%22+%22for+me+to+handle%22 https://www.google.co.uk/search?q=%22This+is+all+too%22+%22f... Then pick the first search result where there is a single word between the segments.

drinkzima 14y ago
Wildcard operator pretty much solves this: https://www.google.co.uk/search?q=I+cant+stand+all+*+your+lies https://www.google.co.uk/search?q=I+cant+stand+all+*+your+li... https://www.google.com/search?sugexp=chrome,mod=11&sourceid=chrome&ie=UTF-8&q=%22This+is+all+too+*+for+me+to+handle%22 https://www.google.com/search?sugexp=chrome,mod=11&sourc...

dalke 14y ago

This is all too complex for me to handle! (And "strange", and "weird", and "crazy" and ...)