One suggestion, which is generally considered a bit of a turn off for most people though, I suspect, is to have an addition question, that asks for the sum of two randomly chosen numbers between 0 and 10. This does mean math, though, which as a rule, everyone apparently hates. 😛
I’ve heard there are some bots/whatever out there that actually put real sites in front of users and have them sign up to it, so that in the background it can put its information in but has a real person navigating the parts that are more tricky for bots. I’m not sure how widely used this system is, nor how effective or not it is, but that’s one possibility for what’s happening.
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