Long Term Memory

Long-term memory is commonly described as being a somewhat permanent store of knowledge, information and experience gained by an individual over the course of their life (Aschcraft & Radvansky, 2010); long term memory is therefore fairly complex and is comprised of multiple different components which can then be subdivided into explicit memory, information stored consciously in the memory such as a colleagues name, and implicit memory, information that when unconsciously accessed can influence our actions and behaviour including everyday tasks such as driving a car or riding a bike. Two key elements specific to explicit memory are semantic memory and episodic memory; semantic memory refers to general knowledge about the world whereas episodic
memory is memories of exclusive events.

In this essay I will expand on and explain these aspects of long-term memory and retrieval in greater detail as well as discussing several explanations of why we forget certain information and knowledge that is stored in our long-term memory.
Explicit memory is signified when someone thinks back to a previous situation they were in or previous knowledge they gained and attempt to consciously access that information, explicit memory requires people to think back to prior exposure and try to retrieve information. Tulving (1972) argued that the two key elements that make up explicit memory, semantic and episodic memory, are very distinct and refer to completely different aspects of long-term memory than each other. Tulving also stated that episodic memory refers to the retrieval and storage of individual events in a specific place at a specific time as well as temporal-spatial relations, yet information about the world, language and general knowledge is stored in our semantic memory. As well as the many differences between semantic and episodic memory there have also been multiple similarities found, Wheeler et al (1997) stated that “There is no known method of readily encoding information into an adult’s semantic memory without putting corresponding information in episodic memory or vice versa” (p.333). Wheeler clearly indicates that we cannot rely solely on one of the elements of explicit memory to be sufficient enough to encode information into the long term memory, whether it be semantic or episodic; it is clear from research such as Wheeler’s that we must have working semantic and episodic memory in order to have fully functioning explicit memory and therefore for us to be able to consciously remember past events or information when we feel it necessary to do so. Explicit memory is evidently incredibly important in order for people to actively participate in every day life and is therefore the element of long-term memory researched in the greatest detail; decisions, however, can also be influenced by our implicit memory, which automatically retrieves previous information without any conscious effort to do so, and the dissociation between explicit and implicit memory is fundamental for normal cognition.
Although there are many complex components involved in long term memory we cannot remember everything and often forget information we have previously learned; research gained from studying short-term memory showed that there of two types on interference that can cause forgetting in the long-term memory: retroactive interference and proactive interference. Retroactive interference is when new information is learned and so old information previously learned is somewhat pushed out and the new information interferes with the remembering of the old information a real life example of retrospective interference in action is if you were to change the route you walk to work and then forget the way you used to walk on your old route, whereas proactive interference is when old information interferes with learning new information with a real life example being, if you have been driving an automatic car for years it could be difficult to get into a manual car and remember how to drive it correctly. These elements of forgetting in long-term memory are often referred to as the interference theory.

The interference theory can be traced all the way back to as early the 19th century when Hugo Munsterberg, a German-American psychologist, changed from keeping his pocket watch in the pocket he had kept it in for years to keeping it in a new pocket and when asked for the time would automatically go to reach for his watch in the pocket that he used to keep it in rather than remembering he had changed to a new pocket, Munsterberg’s old knowledge of his pocket watch being in a certain pocket interfered with his new knowledge that he had moved it into a different pocket, a prime example of proactive interference (Eysenck & Keane, 2005).
Further research showed that both proactive and retroactive interference are maximal when two separate responses have been linked with the same stimulus and minimal when different stimuli are involved. Further significant evidence supporting the interference theory has been found from eye-witness testimony studies where memory of an event or incident is interfered with questioning after the event as the questions asked may somewhat have an impact on the witness’s memory and change their opinion of what they think they saw and therefore reduce their reliability (Eysenck & Keane, 2005). There are multiple ways in which eyewitness’s memory can be affected by interference, one way in which this happens is when the interviewer misleads witness’s with questions that may cause retroactive interference as new or misleading information is given to them
which can cause them to forget the incident they are supposed to be remembering or can alter how they remember, another way in which interference can cause issues with the memory and recall from eyewitness testimonies is if the police or whoever is conducting the cognitive interview were to interrupt the witness as they are trying to recall can cause the eyewitness to lose concentration and this therefore will reduce their ability to recall correctly and thus further interfering with their long term memory (Eysenck & Keane, 2005). Previously, retroactive interference was suggested to have a stronger link to forgetting than proactive interference, however, Underwood (1957) reviewed multiple studies on forgetting over 24 hours and approximately 80% of what had been supposedly learned was already forgotten after the 24 hour period if the participants had previously learned 15 lists in the same experiment, yet only 20% forgetting if no lists had been learned prior to the experiments and these findings suggest that proactive interference does has a large impact on forgetting and support it as being as equally influential on forgetting as retroactive interference. Underwood and Ekstrand (1967) further researched into the long term memory, specifically proactive interference, and found considerable proactive interference in a study in which participants were told to learn words from a list and learning rate of these words did not increase over lists, therefore supporting proactive interference as an important element involved in why we forget things that are in our long term memory.

Overall, it is evident that long-term memory is very complex and made up of multiple important elements, and as the aforementioned studies and research have shown all aspects of the long-term memory play a significant role in both how and why we remember things and how and why we forget things. Explicit and implicit memory have both been shown to contribute greatly to explaining different ways in which we retrieve information stored in our long-term memory. As well as these different ways of retrieval of information being stored in memory, both proactive and retroactive interference have been proven to cause forgetting and despite many psychologists and research studies leading us to believe retroactive interference to play more of a significant role in this, research from psychologists such as Underwood has shown that proactive interference also plays a very important part in explaining why we sometimes forget things that are in our long term memory. There is no clear or simple way to discuss long-term memory due to all these different aspects but there is adequate research to aid the explanation of the multiple phenomena’s involved.