Memory is the mental process used to encode, store and retrieve information. It is useful to distinguish between two types of memory: short term and long term memory. There are four different stages with in our memory; they are called attention, encoding, storage and retrieval. Attention is based on the sensory input. E.g. sound or smell. Encoding is when you transform a sensory into a form that can be stored in memory. Storage is when you hold information in memory until it is needed, and finally retrieval/recall is when you locate the information in memory and getting it out so it can be used.
Theories of memory are based on the assumption that there are three kinds of memory: sensory memory short term memory and long term memory. They also all differ from each other in three main ways. Capacity- the amount of information a memory store can hold. Duration- the length of time the memory store holds the information, and encoding how the memory is processed.
There have been many researchers over the years, which have wanted to understand our memory fully, but have found that our memory system is very complicated, and will have to be eventually broke down.
Jacob miller was a researcher who researched our short term memory. His aim was to measure the capacity of short term memory by devising a technique. His procedure was to use a digit span technique. Based in a laboratory he would ask participants to remember and repeat list of items increasing in length. (The reason why this experiment is based in a laboratory, is because the researcher can have a lot of control over the experiment. One variable that a researcher would want to keep control over would be extraneous variable, as that can affect the end result.) The next participant had to recall lists of digits or letters in the same order presented. To see how accurate this experiment was, he repeated this experiment a many times to see if the results he had were similar, and therefore reliable. However there is one problem with this experiment that may have affected his results Demand Characteristics. Some of the results he had found was the average of short term memory span was between 9 and 5, and it was also easier to recall numbers over letters- numbers recalled better (9.3 items) than letter with (7.3 items). His final conclusion on the capacity of short term memory was the capacity of short term memory is 7+ or -2 items individual difference such as age increase digit span. Also Jacob miller also tested the capacity of long term memory, however he found out that long term memory capacity is infinite as it is impossible to test.
So in this case that the capacity of memory is impossible to test. Another scientist/ researcher wanted to test the duration of long term memory. Actually it was a group of people that worked together to investigate the duration of Short term memory and effects of rehearsal. They used their own technique which is called the brown-Peterson technique a method of measuring the duration of short term memory by preventing rehearsal. The procedure for the technique was to briefly show trigrams of consonants to participants E.G vgt, fcn. Then the participants were then asked to count backwards in 3’s from a given number. After there was intervals of 3,6,9,12,15 or 18 seconds. Next the participants were asked to recall the original trigrams. His findings participants were able to recall 80% of trigrams after a 3 second interval. After 6 seconds 50% of letters were recalled. After 18 seconds recall dropped to under 10%.He also found that short term memory is lost quickly if rehearsal is prevented.
So their final conclusion of their experiment was that the duration of the short term memory could last for a 15-30 seconds. As with long term memory it has the potential to last a life time.
This study adds support to the theory of two memory stores. With using trigrams to prevent rehearsal on the long term