Short-term memory is the first place that information is stored when it enters your brain, and it functions in a manner similar to a holding area. The capacity of short-term memory is between five and nine items, often referred to as "seven, plus or minus two." The items only remain there for about 30 seconds unless the person makes a conscious effort to retain them. The size of the pieces of information doesn't appear to make a difference, as each one could be as small as single letter, or as long as a whole phrase. If they are retained, the items are eventually transferred to long-term, or permanent, memory.
When information enters a person's brain, the first place it stops is the short-term memory, which has a very limited capacity. Only a few items can fit in short-term memory at a time, and they can't stay there for very long before they are either forgotten or stored in long-term memory. The generally accepted limit for the capacity of short-term memory is seven items on average. This number is based on the research of cognitive psychologist George A. Miller, who defined the capacity of short-term memory as seven items plus or minus two. He found that the majority of people could process about seven pieces of information at a time in short-term memory, with some people only able to handle five, and individuals at the upper levels retaining nine.
The limited capacity of short-term memory means that most people can only handle a small amount of information at one time. Without a conscious effort to remember, such as repetition of the information, the items will only be retained for about 30 seconds before they are forgotten. Each piece of information can be any size. For example, each digit of a phone number can be a separate item, or the whole phone number can be treated as a single chunk of information. Another example is that each piece of information could be a single letter of one word, the whole word could be treated as an item, or even an entire phrase.
One way to handle more information at one time is to organize it into chunks, such as remembering a phrase or a whole phone number. This can effectively increase the limits imposed by the capacity of short-term memory, helping a person fit a lot more information into that part of the brain because each item is bigger. New items tend to push out older ones, but if the person practices the information with repetition it can be retained instead of forgotten. Items that are retained and learned in this manner usually are transferred to long-term memory for permanent storage.