A system and method that facilitates and effectuates distinguishing a human from a non-human user. A human interactive proof (HIP) employs images from a large private database of manually categorized images to display as part of a Turing test challenge. The private database contains a sufficient quantity of images, such that the more economical manner to pass the HIP is to employ a human to take the challenge. The owner of the private database makes the database available to the presenter of the HIP due to an alignment of interests between both parties. The HIP is displayed with ads on behalf of the owner of the private database and the presenter of the HIP gains access to a large quantity of private manually categorized images.