# How Valid is Digit Span Research?

On the face of it, studies like the one carried out by Miller (1957) and Simon (1974) tell us quite a lot about how STM works. However, some psychologists claim that they actually tell us very little that is useful or meaningful.

Criticisms like these concern the validity of a study. A study is valid if it gives us truthful or meaningful results.

In this module, you will learn about the factors that affect the validity of a study, and apply a new concept called ecological validity, which is all about the setting a study is carried out in and the way this affects the results.