The criterion is distinguishing words from non-words. That's it. You don't have to know the meaning. You just have to distinguish it from a word-like series of

The criterion is distinguishing words from non-words. That's it. You don't have to know the meaning. You just have to distinguish it from a word-like series of letters. If you incorrectly identify a non-word as a word, your score is penalized in some way.