“To confirm you’re a human being, select all of the images that include traffic signals.”
Chances are good that you’ve seen such a requirement before as you’ve spent time online, whether you were filling out a form or logging into a website. Whether it was an evaluation like the one above, or simply one where you needed to identify a highly distorted series of alphanumeric characters, you probably have also noticed these tests getting more difficult as time has passed. The reason for this is simple: computers are getting better at beating them.