In my biology class, we used to have a quiz on whether students could name five organisms as different from each other as possible. (Feel free to try this yours

In my biology class, we used to have a quiz on whether students could name five organisms as different from each other as possible. (Feel free to try this yourself before reading further.) Some students would name all sorts of exotic and obscure animals -- axolotl, vampire squid -- but these would be scored poorly. All animals are actually pretty close, no matter how "obscure." The best score would simply pick organisms from different kingdoms: Dog, maple, portobello mushroom, amoeba, e. coli. I tried this tactic in the above test, picking common words as categorically distinct as possible (dog, thought, kindness, Tuesday, zero), and received a very low score. It seems that this system prefers the "axolotl, vampire squid..." version of distinctness instead.