types of LTM

• Long term memory is divided into 2 main parts: explicit and implicit. This is a distinction between knowing that and knowing how. Episodic and semantic are examples of explicit (knowing that) and procedural is an example of implicit (knowing how). Episodic memories is concerned with your personal experiences such as your first day of school, family holiday etc. You may also recall the context surrounding the event as well as the emotions you felt as well as who was there. So, the three important elements of episodic memory are the context, emotion and specific details.
• Semantic memories often start out as episodic memories but loose association with the memories attached. They are also about knowing ‘that’ such as 2+2=4 and the capital of England is London. This is more knowledge that everyone knows rather than individual memories. Semantic memories may relate to things such as functions of objects, appropriate behaviour, and also abstract customs such as language.
• . Procedural memories are more unconscious and about how to do something such as riding a bike. Practice and repetition are how they are acquired, and become automatic. It is important that these tasks are automatic so that we can focus on other tasks eg reading a sign of where to go while driving.
• A fourth type of LTM has been suggested which raises questions about the other theories. For example, priming describes how implicit memories influence the response a person makes to a stimulus. eg given a list of words including the world ‘yellow’. Later on, when asked to name a fruit, more likely to respond with ‘banana’ than those not been primed. This is implicit as the memories are automatic and unconscious, but not procedural. This leads to the suggestion of a 4th type of LTM- the perceptual system.

  This suggests that the original theory may be oversimplistic.
• There is evidence from brain damaged individuals.

  HM had difficulty creating new LTMs due to the removal of the hippocampus on both sides due to his extreme epilepsy. HM was able to form new procedural memories, but not episodic or semantic memories. He was able to learn how to draw a figure by looking at his reflection in the mirror, but he had no memory of how this memory was made. (procedural learnt but episodic and semantic memories not made).

  This supports the distinction between procedural and episodic and semantic memories and therefore suggests that they are distinct from each other.
• However, there are problems using brain damaged patients to use for support of theories. It is hard to determine why a specific behaviour is produced due to the fact that the patient is brain damaged and therefore, the behaviour could be due to damage in a different part of the brain (for HM could be due to the epilepsy). This cant really be confirmed on living patients and has to wait until the brain damaged individual has passed. This means we can’t establish a cause-and-effect relationship with a particular brain region and a behaviour to thereby generalise to the population.
• There is however, research support for the different types of LTM.

  Brain scans have supported that they are separate, for example episodic memories are active in the hippocampus and parts of the frontal lobe, semantic memories are also apart of the frontal lobe. Procedural memories are related to the cerebellum and the motor cortex due to the fine motor skills.

  Brain scans therefore indicate that the three types of memories are found in different parts of the brain and so suggest that they are all different.