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The original reCAPTCHA served the dual purpose of fighting spam and training optical character recognition algorithms. It displayed a pair of words, one of whic
by MontyCarloHall 4y ago
The original reCAPTCHA served the dual purpose of fighting spam and training optical character recognition algorithms. It displayed a pair of words, one of which was unambiguously resolved by an OCR and the other of which OCRs couldn’t easily read. The first word was used to disambiguate humans from bots, and the second word was used to train the OCR.
Today, CAPTCHAs serve a similar purpose, except they’re used to train self-driving cars’ image recognition AIs. I always try to be a little subversive and correctly identify the images that are clearly unambiguously classified by the AI, and then purposefully screw up identifying the image that the AI struggles with. It lets me through the majority of the time, which indicates that my bad input made it into their training data.
Unlike the CAPTCHAs of yore, when machine vision simply was not advanced enough to solve them, anyone has access to pre-trained vision models easily capable of identifying the unambiguously resolved buses or crosswalks in the CAPTCHA image. The deterrent to spammers is no longer that actual humans need to solve the CAPTCHA, but rather that it’s too computationally expensive to solve them at scale. Today’s CAPTCHAs are basically Hashcash proof-of-work [0], but with the added benefit to Google et al. (and annoyance to users) that they help train computer vision models.
[0] https://en.m.wikipedia.org/wiki/Hashcash https://en.m.wikipedia.org/wiki/Hashcash
- greesil 4y agoVery insightful. You forgot to mention "and is solvable by a human". Otherwise the captcha would be just be proof of work of some kind.
- MontyCarloHall 4y agoProof-of-work is exactly what Cloudflare’s Turnstyle CAPTCHA alternative is: https://blog.cloudflare.com/turnstile-private-captcha-alternative/ https://blog.cloudflare.com/turnstile-private-captcha-altern... The only reason we still solve those stupid image recognition puzzles is because Google/Waymo and other self-driving car companies have managed to trick us into helping them do their training work for them.
- toastal 4y agoI'm waiting for the check to arrive after all of these years of training—especially after moving to the East from the West and now I have 5× as many prompts.
- rkagerer 4y agoIs there a link beyond that blog post explaining how it's a proof-of-work and how you keep people with thick wallets willing to pay for compute from exploiting?
- porphyra 4y agoWhy do you want to screw up the training data though? You have nothing to gain while making life a little harder for everyone.
- MontyCarloHall 4y agoThe cynic in me says because I resent being forced to help multi-billion dollar companies crowdsource their AI training. The techno-optimist in me says because I want to force them to improve their underlying models. When their engineers notice that their model struggles with weird edge cases that I purposefully mislabel (e.g. when prompted to select images containing motorcycles, I also pick a mountain bike with fat, motorcycle-sized tires), perhaps they will contemplate how to rigorously encode the concepts of “motorcycle” and “mountain bike” into their model, rather than simply pushing an abundance of training data through a black box classifier and hoping that by adding more crowdsourced data, it will eventually arrive at the right answer.
- jrm4 4y agoNot if you believe that the people working on this are going too fast and/or have a misguided goal. I think it's reasonable to believe that real self-driving cars are not inevitable, or even if they are, deliberate disruption of this process is healthy; e.g. it shouldn't rely on something this dumb.
- RockRobotRock 4y agoDo you really think reCaptcha data only benefits Waymo? What about Google Maps detecting stop lights? Or wheelchair ramps?
- ddtaylor 4y agoIf that is something important that we should rely on any company involved in that should be spending the readily available resources to do it correctly, not hoping that random people trying to log in to their email pick the correctly labeled data.
- 4y ago
- Closi 4y ago> It lets me through the majority of the time, which indicates that my bad input made it into their training data. I’ve always assumed each new input is tested multiple times on different humans for validation, but this might be incorrect.
- simmo9000 4y agoBut I do this too...
- Closi 4y agoThat's ok, the chances of several intentional saboteurs on a single image sample are presumably pretty low. i.e. even if the saboteur rate was as high as 10%, and I only showed images three times, only 10% * 10% * 10% = 0.1% of data would have three people intentionally picking the wrong answer. I suspect the rate is much lower, and 99%+ people just want to pick the right answer to get the captcha program to go away as quickly as possible. Images with less than 3/3 matching results in this example would presumably be retested until you got the desired confidence level. Then assuming your ML model isn't overfit/overtrained, you could even then assess your original input data to detect/flag anomalies for manual review.
- teddyuk 4y agoI figured this out a while ago and I do it as a challenge - how can I incorrectly pass the test - probably there are more of us doing this than you estimate? We could be in the majority (unlikely I know)
- bogomipz 4y agoHow about the text ones that Google uses that are text that are alternately compressed and stretched in the same word to the degree that many of them are completely illegible to human eyes? Some of them appear like text wrapped around an invisible sphere almost like a mercator projection. What meaningful work domain is those captchas targeting?
- SrithranHi 4y ago> a pair of words, one of which was unambiguously resolved by an OCR and the other of which OCRs couldn’t easily read 4chan had a lot of fun with this when it was first implemented. Perhaps unsurprisingly, there very quickly developed a campaign to have everyone insert "n**r" in place of the unknown word. Many threads were dedicated to education, onboarding, and, of course, sharing 'trophies' when such a replacement was found to have taken effect in one of Google's products (Books, iirc?).
- omoikane 4y ago> It lets me through the majority of the time Maybe the system has determined that you are human and you are intentionally attempting to mess with them. Since the primary goal of CAPTCHA (confirm that you are human) has been fulfilled and you appear to not be a good source for the secondary goal (crowdsource training data), the system decided to not waste any more time with you.
- gambiting 4y ago>> It displayed a pair of words, one of which was unambiguously resolved by an OCR and the other of which OCRs couldn’t easily read. The first word was used to disambiguate humans from bots, and the second word was used to train the OCR. Was I the only person who has always inserted some nonsense word as my answer for the clearly scanned word? It was very obvious which word was generated and would be checked, and which one was scanned and which wouldn't be checked just accepted as-is. I always just typed in something else other than the word - I think it was just being contrarian against being used by a corporation to do their word recognition for them for free.
- rollcat 4y ago4chan famously promoted the usage of the n-word for that purpose. You're going to get enough wrong answers even with compliant users - I'm 100% positive any dev with at least two brain cells and a passing grade in statistics would be able to filter all of these out of the dataset. But yeah, I also cross the street on the red light.
- huggingmouth 4y agoI do the same with the self-driving training images. Want reliable input? Pay me.
- rkagerer 4y agoCrazy, I always assumed they sent the same prompts to multiple users and cross-checked.
- gambiting 4y agoI mean, they probably do - so if 9/10 people said the word is "apple" and I said it's "banana" then it will accept apple. But at the same time I can't imagine I was the only one doing this.
- rkagerer 4y agoSure, but unless you're coordinating with other adversaries it shouldn't be hard for them to filter out the deviant responses.