Re: perl recaptcha?

MJ Ray wrote:
> Jonathan Rochkind <rochkind_at_JHU.EDU> wrote: [...]
>> And then fails. Anyone managed to do this, or have any other advice for 
>> using Recaptcha from perl?
> 
> Please don't use it as a barrier on the only access route to a
> service, else you will be locking out humans with vision or hearing
> problems, or even simply high browser security settings.
> 

Does anyone know anything concrete about "cognitive" captchas?  I've run 
into anecdotal support for things like:

   Enter the word "orange" <input name="foo">

Or:

   Enter the number that answers: How much is two plus
   two? <input name="foo>

Or even:

   Leave this input blank: <input name="email">...


Are these known to work?  Or are they just clever guesses about what 
bots might not be able to figure out?


-- 
Thomas Dowling
tdowling_at_ohiolink.edu