When considering human information processing capacity, Working memory span is mostly independent of item complexity, so we must distinguish between the number of items being processed (a ”chunk”, limited by Span of working memory) and the complexity of each item (separately limited by Span of absolute judgment).
Miller writes (1956, p. 92):
I have fallen into the custom of distinguishing between bits of information and chunks of information. Then I can say that the number of bits of information is constant for absolute judgment and the number of chunks of information is constant for immediate memory.
Especially with more complex recoding schemes, chunks can represent fairly abstract attributes: e.g. a musician thinking about “tension” when improvising, or a chess player thinking about “lines of force.”
Miller, G. A. (1956). The magical number seven, plus or minus two: Some limits on our capacity for processing information. Psychological Review, 63(2), 81–97. https://doi.org/10.1037/h0043158 Miller - The magical number seven, plus or minus two