Short-Term / Long-Term Memory

One of the great rules-of-thumb in cognitive science came from psychologist George Miller, who described the "magic number 7, plus or minus 2". Miller suggested that people could keep in mind from 5 to 9 things for a short while after they learned them. More than 9 items required special training, and fewer than 5 items could be learned in a single try.

This magical number regarding memory, 7, refers to what people can keep in what has been called working memory that includes what you are currently thinking, but not what you thought about an hour or a day or a year ago. Whatever is currently active and in use in the brain is generally referred to as Short-Term Memory (STM). The basic characteristics of STM is that it is fast to recall but can quickly be forgotten. The rate at which things are forgotten and lost from STM is one of the most solid findings in psychology, and looks like an decay function, with half of what is learn being forgotten within 9 seconds, depending on task conditions.

Getting information or feeling back in mind from the past involves retrieving it from other areas of the brain, and has been called Long-Term Memory. The purpose of good teaching is to keep moving a well-attending student's thinking and learning from Short-Term to Long-Term Memory.