# Digit Span Evidence: Summary

You have now completed the module on research studies that used digit span. The most important ideas are:

- Miller (1957) discovered that STM seems to have a fixed capacity of 7 plus or minus 2 digits.
- Miller also discovered that chunking increases the capacity of STM.
- Simon (1974) found that STM capacity depends on the size of the chunks of information used. A person can store up to seven small chunks of information, but only two or three larger chunks.
- Therefore, whilst STM capacity is larger than the seven digits suggested by Miller's research, it does have an overall limit.

End of module

## What do you want to learn about next?

- Recency measures of STM (basic level)
- The research issue of ecological validity (advanced level)

## Navigation

Basic level content | Start | Digit span measures of STM | Recency measures of STM | Test your learning
Intermediate level content |  | Research using digit span measures | Research using recency measures |
Advanced level content |  | Ecological validity and STM research | Sampling validity and STM research |