# Measuring STM Capacity 1: Digit Span

The easiest way to measure the capacity of STM is to get people to try to hold increasing amounts of information in their STM. When they start making mistakes, we can assume that the capacity of STM has been reached.

You can use the buttons on the right to find out what happens to Professor Rowell Huesman when we gradually increase the amount of information in his STM.

We need to use small pieces of information, so we can accurately measure how much information the person's STM is holding. On example of a small piece of information is a digit (a single number).

Using these ideas, we can design a simple experiment to measure STM capacity. We give people lists of digits to recall. The list gets longer by one digit each time. If the person can recall all the digits in the right order, then we can assume that they haven't used up all the capacity of their STM. However, once they start making mistakes, then we can assume that they were trying to store more information than their STM had room for.

A person's digit span is the number of digits they can recall accurately and in order.

Fill up my STM with information and see what happens...