Until now, it's been assumed that people with high capacity visual working memory had greater storage, but actually it's about the bouncer -- a neural mechanism that controls what information gets into awareness.
What we're able to show is that it's possible the storage space (of all people) is more or less about the same. The difference is not how many things you can hold in (short-term) memory at the same time, but how efficient you are at keeping irrelevant things out.