The test subjects were presented the "real" words with fake words mixed in, like "stoinka" or "gomuti" or "alsike".

So to "recognize" a word simply meant, did the test subject says "yes, this is a word used by English speakers", and not "yes, I could define it or give an example of the word's usage in a correct context".

There are several words in this chart that I cannot associate with anything, nor recall having seen them before. At least personally, I would say I know a word by knowing under what context it can be used, and I don't even have that.