eli5: How do Captcha’s know the correct answer to things and beyond verification what are their purpose?

Question

I have heard that they are used to train AI and self driving cars and what not, but if thats the case how do they know the right answers to things. IF they need to train AI to know what a traffic light is, how do they know im actually selecting traffic lights? and could we just collectively agree to only select the top right square over and over and would their systems eventually start to believe it that this was the right answer? Sorry this is a lot of questions

In: 3352

Answer 1

Top answer is correct, but ommits some critical information. After all, some Captchas ask you to simply check a box. Asking you to identify the correct images is only half the puzzle.

In the background, it also checks HOW you select the pictures. Computers being robotic, and humans being.. well… humans, we both have very different ways of clicking on things.

A very good example is the timing. Computers generally measure time in milliseconds. There are 1000 milliseconds in a second. If I ask you to click on five objects, the amount of milliseconds between each click would vary, greatly. 500…295…106…952…431.. all (mostly) half a second apart.

Computers have very structured processes. They almost always complete the same action in almost the exact same time (specific to the actual computer, how fast it can generally do things, and how much else its trying to do at the same time). If I was to ask a computer to click on five objects, the milliseconds between would look more like 50… 80… 30… 70…100. They still vary.. but nowhere near as much as a human.

Yes, in this case you could tell the computer to wait a random time between each click, but there are many other details about the way they click that outs them as computers.

We don’t know the full scope of this. If we did, it would he that much easier to make a bot that could fool the system, so companies will not tell you the exacts.

TLDR; They look at the finer details of your mouse clicks (how long it takes between each click as a basic detail, for example), and computer vs human input is very, very different. They still check the right pictures, as others have said, but that’s only half of it. We live in a world of machine learning. Computers can tell which pictures have traffic lights in them pretty easily.