It is possible to distinguish between three forms of memory:
- ultra short-term memory (or sensory storage);
- short term memory (often referred to as working memory)
- long-term memory.
Ultra short-term memory has already been described when examining the role of sensory stores. It has a duration of up to 2 seconds and is used as a buffer, giving us time to attend to sensory input.
Short-term memory receives a proportion of the information and allows us to store information long enough to use it. It can store only 5 to 9 items of information, for a short duration, typically 10 to 20 seconds. The capacity of long-term memory appears to be unlimited.