They assume that a computer will detect faces where humans do not and use such a selection as a captcha. It forces the computer to make a random guess against its matches so there is still a chance of it getting the right answer, but it's an interesting concept.
Interesting, but my iPhone won't have any luck getting into computer-only clubs: It successfully detects the human face in this image[1] but none of the dot patterns.
A lot of artistic value, but not so many practical applications.
To bypass this, a bot can simply be tweaked to draw a frame shifted of x and y pixels in any direction after correctly guessing a face. The system will see no match with the non-detectable-by-a-human face and therefore it will think the bot is a human.
I agree. It seems this could be used to determine only whether the testee is not-human. It's trivial like you say, to trick the test into believing it is human by not finding a face.
At first glance I thought the test was only to determine whether the testee is definitely not-human but the description actually implies categorising into computer and not-computer:
"FADTCHA(FAce Detection Turing test to tell Computers and Humans Apart) is a type of challenge-response test to determine whether the response is generated by a computer. The test involves asking a testee to find* a face in a presented image and draw a square region of the face. If one correctly finds a face, it can be presumed that it is a computer, otherwise it will be regarded as a non-computer."
It's a joke on using a Captcha to detect a human user - this is the opposite, a way of only allowing robots to access information, and to keep away humans.
I was explaining why, in my opinion, the facial captcha project isn't very functional, at least as it is described on the artist's website.
It was an explanation of the simplest method a bot could use to game that system.
They assume that a computer will detect faces where humans do not and use such a selection as a captcha. It forces the computer to make a random guess against its matches so there is still a chance of it getting the right answer, but it's an interesting concept.