I’ve found that the cognitive reflection test is a very nearly 100% effective “captcha” for wikis and forums. None of the image-based captchas I’ve used have been anywhere near as effective. Apparently a lot of spam posting is done using humans, but they aren’t smart enough to pass the CRT. (Obviously, this will stop working if enough sites start using it and the answers become well known.)
Any “captcha” you code yourself—even one as simple as “uncheck this to post”—will be far more effective than one built in to your wiki software, because spammers won’t bother to add code to their system just for your site.
I’ve found that the cognitive reflection test is a very nearly 100% effective “captcha” for wikis and forums. None of the image-based captchas I’ve used have been anywhere near as effective. Apparently a lot of spam posting is done using humans, but they aren’t smart enough to pass the CRT. (Obviously, this will stop working if enough sites start using it and the answers become well known.)
Any “captcha” you code yourself—even one as simple as “uncheck this to post”—will be far more effective than one built in to your wiki software, because spammers won’t bother to add code to their system just for your site.
That’s not quite true anymore. Most spam does come from software spambots, but some “spambots” are actually people.