Well, in a sense, you have to look at more images for your test than mine because the only reason I am picking 3 images is because often times Google images' first result does not give a good picture of a specific term. If you are only picking one image per word, sure, your chances might be a *little* bit better with your test that you can rule out all the other words using the other images and figure out an ambiguous image, but I think you eliminate a lot more ambiguity by showing 3 images per word. The chances of getting 2 words whose images look completely unrelated to the words is relatively high in your test, I fear. Also, that process of elimination can be significantly more taxing on the user. Easier to have more clues. When I think about it, looking at images is much quicker than picking a word from a list, too, so it seems easier to select 1 of 6 words 3 times that to select 1 of 6 words 5 times (and let the remaining word be the only choice). Technically you're not selecting 1 of 6 words each time, but in a sense you are because you still want to consider every word for every image in case you didn't pick the best match in an earlier choice. If we were to make the user pick from a completely separate list for each image clue (or trio of image clues), I think it would be about the same amount of effort on the user's part, but provide significantly more security in eliminating random success: 6^5 = 7776.