[pmwiki-users] Turing Test for pmwiki

Marcus prima at wordit.com
Sun Jul 13 15:26:58 CDT 2008

Hi All,

I've devised a more advanced Turing Test because I was very unhappy
with the current graphical captcha solution in pmwiki. The biggest
problem is accessibility. The current solution blocks out people with
impaired sight, usually elderly people which is a large number, and
the blind altogether.

One workaround is to provide speech delivery of the captcha code, but
I thought why not change the test and use a little more AI smarts. For
those unfamiliar with it, the Turing Test is a challenge to determine
whether the responder is human or a machine.

Instead of an obfuscated number to fool OCR systems, let's use plain
text questions which cannot be answered without real-world knowledge.
This would cause a spam robot to fail the Turing test, and no amount
of OCR advancement will change it.

Some applications like forum boards are using arithmetic, e.g.:

"What is 2 + 2?"

Or using words:

"How much is five minus two?"

That's not bad, but arithmetic does not require real-world knowledge.
Arithmetic can be programmed easily. So I thought a bit farther. The
questions are quite tricky to devise because any human should be able
to answer them. I think the best general solution are the kinds of
questions you could ask a child at kindergarten age.


Which day follows Monday?
How many months are there in a year?

Note: These follow a pattern and could be programmed easily, but are
okay as a low barrier level.

What colour is a green apple?

Note: Humans need to be informed this is not a trick question, the
answer is "green".

- What is larger, an elephant or an ant?

- Which animal can fly, a mouse, a bird, or an elephant?

- Is steel hard, soft, or furry?

- Is rain dry, wet, or rough?

Note: these are multiple choice so they could be figured out by trial
and error. However, if the questions are rephrased, then the actual
question and the answers may not be clear which is which. e.g.:

- Are mice like monkeys or hamsters?

- When does the sun rise? In the ....

- How many corners does a square have?

- What shape is a circle? It is ro... (provide the first letters as a clue)

I started wrote some simple code to implement it in a contact form,
which now works. However, I don't know how to integrate it into pmwiki
like the captcha recipe. Can anybody help with that?


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