Pictcha is an experiment designed to improve security over typical text-based CAPTCHAs and enhance image search.
CAPTCHA is an acronym for completely automated public turing test to tell computers and people apart. It ensures that an online transaction is being performed by a human rather than a computer.
CAPTCHAs have been successfully used to distinguish people from computers by challenging users to decipher distorted text, a task that is relative easy for people but quite difficult for computers.
However, with the improvement of machine-learning algorithms, CAPTCHAs must be regularly updated to thwart would-be spammers.
In the Pictcha experiment, we show users a randomly selected Web image and challenge them to provide two descriptive labels.
Passing the test requires that at least one of the user-provided labels matches a known tag for the image. The collection of known tags is generated by previous users who have tagged the same image.
Pictcha was created by the Economics and Social Systems group.
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