Yesterday, image CAPTCHAs were enabled for all anonymous edits on all Wikimedia Foundation wikis (including the popular encyclopedia Wikipedia). I noticed this by chance because I’m in a computer lab right now and found some vandalism on an article linked from the main page, but didn’t want to take the time to log in first. However, by the time I finished typing in the CAPTCHA, an admin had already reverted the vandalism. Drat.
The reason for the CAPTCHA is that we’ve been having some spam problems on-wiki recently, with spammers using automated bots to add links to dozens of pages before they end up being blocked. We have a global spam blacklist that does a good job of stopping spammers dead, but all of their edits still have to be manually reverted, which is a pain. Hopefully this new change will alleviate some of that. This change will basically stop all anonymous bot edits (including legitimate bots that get logged out by accident). It will also stop vandalism bots that are running anonymously, which we’ve seen a few of.
Unfortunately, this change still doesn’t do anything against spamming/vandalism being done using registered user accounts. Yes, you do have to pass an image CAPTCHA to register an account too, but that’s only once per account rather than on every edit, so people could conceivably manually register a bunch of accounts and then hand the account details off to their bots.
What I’d like to see is CAPTCHAs on the first twenty edits of each new user (in addition to each anonymous edit). This would make automated spam/vandalism impossible.
One thing I’m worried about though — are we making the barriers to edit too high? Anonymous edits do contribute significantly towards writing the encyclopedia. There’s a trade-off between making it hard for automated ne’er-do-wells and putting a burden on legitimate editors who just can’t be bothered to login or register an account. I hope we haven’t gone too far in one direction.
Update: It looks like CAPTCHAs have been disabled; read the comments for more information.