I enjoyed the article and agreed that working memory places a fundamental limit on the intelligibility of otherwise equivalent pieces of code. As a former psychologist with experience of memory research (though not quite this area), it might be useful to others if I add that:

- The size of the short-term store is normally said to be 7 plus or minus 2 (the 'magic' number 7)

- The Working Memory model has somewhat overtaken the 'short term' memory model, and it is unusual to see them being presented alongside each other like this (though 'short term memory' remains a useful, good-enough metaphor for explaining certain key aspects of memory)

- Chunking is typically viewed as a memory-supported division of stimuli (what you're reading, hearing etc.) into meaningful units based on LTM memory representations. A good example is a chess expert 'chunking' the layout of a chess board with many pieces in perhaps one or two units (e.g. 'It's the mid game configuration of [famous players] in [famous game], except the king's position is different'). We would expect more expert programmers to 'chunk' increasingly large units, I think (e.g. 'Oh, this is just the [famous sorting algorithm]').

- A single chunk is usually considered to take up a 'slot' in short term memory

If anyone wants papers/sources for the above, let me know.