Prior knowledge gets around working memory limits

[I]t’s well known that extensive background knowledge allows one to circumvent the limitation of working memory. To take an obvious example, if I ask you to hold six letters in mind for one minute, it will be much easier to do with B-R-A-K-E-S than with X-P-W-M-Q-R. Although both are a string of six letters, the first forms a word, so you can treat it like a single unit. It’s like holding one thing in working memory, not six. Naturally, this saving of space in working memory only works if you know the word “brakes.” The same phenomenon is observed in many other domains. The chess expert looking at a board does not see 16 white pieces—she sees several clusters of pieces, each cluster defined by the relationship of the pieces to one another and to opposing pieces. Whether it’s chess pieces or letters in a word, the compacting of many things into one thing in working memory is based on prior knowledge.
Have Technology and Multitasking Rewired How Students Learn? by Daniel T. Willingham