What word do you think of when you scroll down this page?
The ability to detect some feature common to a number of complex, natural scenes is something which only people can do*.
Today’s invention is therefore a captcha-type security tool which distinguishes between people and bots by asking registrants to type in the word which links a collection of such images.
This would be inherently much more difficult than asking eg how many giraffes are in the picture…which is clearly guessable.
It might be possible to simply send people to a page on Pinterest, with any captions removed. Certainly, Google image search doesn’t work in this context because some of the images which appear in response to a general search term ‘arch’ are explicit diagrams or may actually contain the word itself).
(* Although this kind of software could detect ‘arch’ es, it would have no ability to discern that this was what linked all the images on a page).