Working Memory And Simon Sequence

Working memory is the information your brain holds and uses right now, separate from information stored in long-term memory that you have to search for.

In 1956, psychologist George Miller published a paper titled “The Magical Number Seven, Plus or Minus Two.” Miller found that most people can hold about 5 to 9 items in working memory at one time.

The Simon Sequence game on this site uses the same method researchers use to test working memory. The game shows a pattern. You repeat the pattern. The pattern grows by one step each round. This is a direct test of working memory, not an indirect one.

Why working memory matters for programming

Reading code uses working memory. When you read code, you hold multiple facts at the same time: what a variable represents, what the last function call returned, what state a loop is currently in, what you are trying to accomplish. Code that is easy to read is code that requires less working memory to hold: short functions, clear names, one task per function. Code that is hard to read requires you to hold too many facts at once. A single function that does 6 unrelated tasks is hard to read for this reason, not because the logic is wrong.

Working memory improves with practice

Working memory capacity changes less than IQ does, but working memory capacity does improve with practice. Practice improves a specific skill: grouping information into fewer, larger units. This is called chunking. A beginner sees a 9-tile pattern as 9 separate items to remember. An experienced player notices structure in the pattern, for example “the 4 corners, then the middle, twice.” The pattern becomes 3 items instead of 9 items.

This same chunking skill lets a programmer hold an entire function’s logic in their head, instead of losing track partway through reading it.

Try it

Play Simon Sequence for 5 rounds. Notice the exact level where the pattern stops feeling automatic and starts feeling difficult. That level is close to your current working memory limit. Play again after a week and check if that level changed.