This question is something we've also been asking
ourselves on the E3
team,
as part of our work on account creation. I think we
all agree that
CAPTCHAs
are at best a necessary evil. They are a compromise we
make in our user
experience, in order to combat automated attacks.
That's kind of missing the point of the original poster. The point being
that they are an *un*nessary evil and do not prevent automated attacks
whatsoever.
[Snip]
To get more numbers on how much taking away the
CAPTCHA might gain us in
terms of human registrations, we have considered a two hour test (to start
with) of removing the CAPTCHA from the registration page:
https://meta.wikimedia.org/wiki/Research:Account_creation_UX/CAPTCHA That
kind of test would probably not be an accurate measurement of what kind of
spam would be unleashed if we permanently removed it, but the hourly
volume
of registrations on enwiki is enough to tell us the
human impact.
That would be interesting. Remember that captchas arent just on the user
reg page though.
-bawolff