Magic Number 7 Plus or Minus 2
George Miller’s claim that short-term memory capacity is roughly 7 ± 2 items (five to nine).
What counts as an "item"?
Capacity is measured in items at whatever level of abstraction you’re working at, not raw atoms. A phone number can be 10 digits or 3 chunks.
- Chunking is how you break the ceiling
- Later work suggests the real number is closer to 4 once chunking is controlled
- 7 ± 2 is still the canonical framing