Short term memory is the memory store that holds information that we are currently attending to or that we attended to very recently.Although short term memories last much longer than sensory memories, short-term memory can hold only a small amount of information up to about seven items at a time. If you recite a list of unrelated numbers to people and ask them to repeat the list, they can usually handle up to seven or sometimes eight or nine items, but not more. That’s one reason why it makes sense for telephone numbers to have seven digits.
Examples of Short Term Memory In your Daily Life
When we look up a new number, we can usually keep it in mind long enough to dial it. Although the capacity of short-term memory is limited, its span can be increased by organizing inputs into larger “chunks”. Short term memory is limited not to approximately seven letters or seven numbers but rather to seven pieces of information, which could be seven numbers, seven words, or seven items in a photograph. Thus, if we can manage to code a set of letters or numbers into a single piece of information, such as a word or phrase, the capacity of our short-term memory will be increased. For example, try reading the following list of letters to a friend and ask her to repeat them back to you:
U S A I B M F B I N F L
This string of letters is well over the seven-item limit. But if your friend memo- riles them as well-known chunks (USA, IBM, FBI, NFL), the list consists of only four items and can easily be remembered. In general, short-term memory can hold items fairly well for the first few seconds. After about twelve seconds, however, recall is poor, and after twenty seconds the information has disappeared entirely (Peterson & Peterson, 1959). As a result, if you look up a phone number but don’t dial it immediately, you may have forgotten it by the time you turn to dial. You can keep the information in short-term memory for a longer time by mentally rehearsing it—repeating it to yourself so that it does not get lost. Let’s say that you have looked up and dialed the number of a pizza takeout place, only to find the line busy. To avoid having to look it up again, you can keep saying the number to yourself (“298-5529, 298- 5529, 298-3529 until you finally get through.
Short-term memory is often called working memory. It is the memory store that is in our consciousness and that we work with whenever we answer questions or solve problems. See if you can solve the following problem, as suggested by Mark
((4 + 5) + (12 +4))
In Order to solve the problem, you must compute the separate quantities, keep them in short-term memory, and then combine them to come up with the overall solution. Short-term memory thus serves as a sort of mental “scratch pad” in which we ‘ ‘jot down” information that we need for later processing. As we will see, much of the information that we need co work with—such as the value of 12 + 4—is filed away in long-term memory. Before we can use that information, we must transfer it from long-term storage to [he “scratch pad” of our short-term (or working) memory.
We often keep material in short-term memory for only as long as we need it, and then we discard it. Thus, a phone number that we look up and dial without rehearsal is often forgotten by the time the call is answered. The next time we need the number, we have to look it up again. Bur some of the material that enters short-term memory is not lost along the way. Instead, we manage to transfer this material to long-term memory for later reference. Thus, there are some telephone numbers that we once had to look up but now know by heart. These are the numbers that were important enough for us to file in long-term memory.