That's closer! But the devil is in the details. They have you looking at one image, reading the question, and rating up/down and even commenting. In the image, they have a full body shot, with simply "Does this work?" Does what work? The glasses, the shoes, the dress?

This takes a lot more effort than simply tapping one of two photos without reading anything. A/B responses can be given in less than a second. It's all snap judgements -- no reading is necessary.