How can forgetting over the short term be explained best?

Human memory, like memory on a computer, allows us to store information for later use. Unlike a computer however human memory doesn’t only have two types of storage for information. Whereas a computer either has permanent storage or permanent deletion humans have three distinct storage capabilities. Sensory memory is very brief only lasting a few seconds and is replaced by Short term memory when the information in our sensory memory comes into the conscious or our awareness. Information in the short term memory is information that is currently active, such as reading this page. Although short term memory can definitely last longer it still has a very limited capacity. Finally there is the long term memory store, which is the one most similar to the permanent storage of a computer. Forgetting over the short term occurs when information from the short term memory store is lost before you are able to commit it to your long term memory store.

Forgetting over the short term can be put down to an overload of information in the short term store. Information in the short term store is very short lived if not backed up and refreshed. If you consider working in your room, whilst their you note all kinds of irrelevant goings on such as a child crying, someone walking down the corridor or a phone ringing off in the distance somewhere. However, although you notice them such matters are almost instantly forgotten. There are number of possible reasons for this, it could be down to decay, displacement, recency effect or quite simply the capacity of the short term store.

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Ebbinghaus (1885) and Wundt (1860s) were (as cited by Gross, 1992) two of the first psychologists to maintain that short term memory is limited to a specific number of pieces of information. They claimed that the short term memory could hold about 7 bit of separate information in different slots, so to speak. This size was later argued by Miller (1956) to be expandable if information was chunked together. The idea that the short term memory has a capacity limit may go some way to explaining why we forget things so quickly, like when someone reads you a telephone number and you almost immediately forget some of the digits. If there is only a certain amount of space then items may somehow be pushed out of memory by other items that are entering. This is called displacement as the new items tend to displace old ones. So if there is a lot of information coming in in order to prevent the short term memory being cluttered some information is pushed out to make room for new information. When it comes to learning, if you had one blackboard with nothing on it you would get no information from it. If you had a blackboard that the teacher wrote your lessons on and then did not wipe it at the end of each day but instead tried to cram the whole years worth of work onto it, on top of the previous lesson, squashed into the margins etc again you wouldn’t be able to get any information as deciphering it would be impossible. This is the same with memory; if information wasn’t pushed out you would be overloaded and unable to decipher anything. So forgetting over the short term can be partially explained by the making of room for new information. Although this may seem to be a very logical explanation as to why we can forget certain things almost as soon as we hear them it does rely heavily on the assumption that there are definitely a limited number of slots.

Another idea behind forgetting over the short term is down to the fact that displacement may occur before there is a chance to rehearse the information. As long as information in the short term memory is regularly rehearsed, it can apparently be maintained indefinitely (Bjork, 1996). When someone tells you something that you know you need to remember, like a phone number, you repeat the number over to yourself to help you remember it. If this rehearsal is prevented and the information is not re-circulated through the short term memory then rapid forgetting occurs. The process of repeatedly verbalising or thinking about information will not necessarily get it into the long term memory but it will keep it in the short term memory a little longer. So prevention of rehearsal can also lead to forgetting over the short term.

When receiving information, the information perceived first is more likely to be remembered. It may be that this information is rehearsed more or that it gets to the long term memory more easily. This is know as the Primacy effect and has most effect during repeated messages when there is little or no delay between the messages. One reason that the primacy effect works is that the listener is likely to start off paying attention and then drift off when the subject gets boring or drags on. If the person’s attention falls then it is likely that they will not remember the information being presented even though they will have only just heard it. The limitation of memory also plays a role and we can miss the middle as we continue to rehearse and process the initial information. Thus again some of the information that we have only just been told will be forgotten almost immediately. This can be seen in experiment carried out by Solomon Asch (1946) where he asked about a person described as envious, critical, impulsive, stubborn, industrious and intelligent. He then asked a different group of people about a person with the same list of attributes but changed the order of the words so that intelligent and industrious were the first words and not the last. He found that the second group rated the person more highly than the first indicating that what they remembered about the person were the first words of praise and positive attributes.

Information perceived towards the end of an event is also more likely to be remembered. This is know as the Recency effect and means that the stuff in the middle tends to be lost and forgotten quickly. So when you are presented with a list of digits, you are likely to forget the middle ones far more quickly than any of the others. So the order in which information is presented to you also has an effect on forgetting over the short term.

So it can be seen that forgetting over the short term can be explained best by a number of different reasons. However it seems most likely that it is due to a combination of the above discussed points as opposed to one alone. There is obviously only so much you can take in at a time and thus it stands to reason that your short term memory will become cluttered. Even if it is not a case of only 7 slots everything has a capacity limit and once this is reached some information is bound to be pushed out in order to make room for the new stuff. Some of the information you have taken in may be displaced before you have the chance to rehearse it thus increasing the likely hood that you will quickly forget it. So displacement and lack of rehearsal go hand in hand when it comes to forgetting certain things almost as soon as you have heard or seen them. Primacy and recency effect also go hand in hand as both are to do with the order in which you hear information and thus the attention you are paying to certain parts of the information. There are a number of different contributing factors as to why we forget over the short term and this forgetting should be considered as a combination of them and not solely down to one.

References.

Gross, R. D. (1992) Psychology. The science of Mind and Behaviour. (2nd Ed) P334-341

Miller, G. A. (1956) The magical number seven, plus or minus two: some limits on our capacity for processing information. Psychological Review. 63, 81-97

Bjork, E. L. & Bjork, R. A. (1996) Memory. Handbook of Perception and Cognition. (2nd Ed) P113-118