Working Memory and Digit Span Guides

To read a digit span score properly, you need to know what the task actually measures. These guides draw on classic studies and meta-analyses, with sources cited.

01 Working Memory and Digit Span — From 7±2 to 4±1 What digit span measures, and the conditions behind Miller's "magical number 7±2" and Cowan's "4±1", explained from the original research.
02 Forward vs Backward Digit Span — What's the Difference? Repeating digits in the order you heard them and saying them in reverse make different demands. A comparison of what each task measures, with common strategies and mistakes.
03 Chunking and Mnemonics — How to Group Digits What makes people who remember more than 7 digits different? The principle of chunking, the experiment that stretched one person's span to 79 digits, and memory techniques that are actually useful.
04 Why Phone and Card Numbers Are Split into Groups 010-1234-5678, 1234 5678 9012 3456. The habit of splitting long numbers into groups of three or four is closely tied to the limits of working memory. Here is why, along with the actual numbering standards.
05 What Affects Working Memory — Sleep, Anxiety, Noise and Age The same person may remember 7 digits one day and 5 the next. Here are the factors research has shown to lower working memory performance, plus the testing conditions that matter.
06 Why Digit Span Differs Between Languages A study where Chinese speakers had longer spans than English speakers, and another where spans shrank when measured in Welsh. How the spoken length of number words changes memory span.
07 Does Memory Training Work? What the Research Says Will digit span practice or brain-training apps make you smarter? What large experiments and meta-analyses say about what improves and what doesn't.
08 How Digit Span Is Measured — This Test's Rules and Limits How the standard digit span task is given, what this site does the same and differently, and an honest look at how your device and environment affect results.