Types of LTM

Episodic, semantic & procedural

Tulving (1972) came forward and argued that the MSM’s theory about LTM is far too simplistic and therefore lacks validity, as it does not account or apply to different forms of memory. He therefore put forward a new theory outlining 3 store components of LTM.

Episodic memory:

Episodic memory contains the details of your life, almost like a diary. For example if I were to ask you about your life you may tell me about some key events in your childhood, your school life, your family life etc. Episodic can be summed up by the WWW criteria: ‘What, Where and When.’ The ‘when’ implies that episodic memory is time-stamped. We can recall when an episodic memory occurred.

Episodic memory also tends to involve explicit recall. If I were to ask you what you learned in yesterday’s incredible lesson, you would need to go through a process of conscious recall. You would be aware of that process of thinking backwards.

Semantic memory:

Semantic memory refers to the facts / information about the world / knowledge memory / the meaning of words. This has been compared to a dictionary or encyclopedia. Your semantic memory would be your understanding of what an experiment is, or the meaning of words such as reliability and validity.

Semantic memory is not time-stamped. Generally you won’t recall the day you learned reliability, or the Milgram study.

Procedural memory:

Procedural memory refers to action-based memory or a memory of how to do something. It relates to the skills and tasks, for example knowing how to pass a ball in netball, play the piano or HM’s ability to trace a circle in a mirror. Again it is almost unheard of for procedural memory to be lost in cases of amnesia.

Procedural memory is more implicit in its nature. It does not require conscious recall, in fact if you focus on playing a musical instrument or any other well-rehearsed task it is likely to impair your performance. If you’re asked how to ride a bike or control a clutch it is almost impossible to describe. Procedural memory works in practice rather than be explicable in nature.

Snyder et al (2014) beautifully illustrate the nature of procedural memory. They tested experienced typists. The letters on the keyboard were blanked out but the touch typists were still able to type without impairment. However, when they were asked to label the blanked out keys they could only do it with 57% accuracy. This is a perfect example of procedural being intact even in the absence of semantic memory. Implicit in the absence of explicit.

Evaluation of LTM – Theory: SAUNDERS

Research to support: The case of HM would support Tulvings idea of different memory stores in LTM. In addition, Clive Wearing is a prominent British musician. In 1985, he contracted a herpes virus that caused swelling of brain tissue resulting in damage to his hippocampus. Because the hippocampus is important for the creation of long term memories, his injury resulted in an inability to form new explicit memories following the injury, also called anterograde amnesia. He does not remember moments from his childhood, nor does he remember the names of his kids from his previous marriage. One of the few memories left intact is his love for his current wife, Deborah Wearing. However, he is able to do motor tasks that he learned prior to the hippocampal damage, for example, sight read piano music and conduct a choir. However, he would likely have no recollection of doing either of those things minutes after completing the task. In the video you will see that Clive’s Semantic memory was unaffected – he still understands the meaning of words. Clive’s Procedural memory was also intact – playing the piano, walking, tying shoe laces etc. However, his Episodic memory was severely impaired –both Clive and Henry Molaison could only remember a few elements of his childhood. This supports Tulvings theory that there are separate stores for LTM. This is because one store can be damaged, others stay intact, this is suggests that the separate types of LTM ARE IN DIFFERENT PARTS OF THE BRAIN.

Scientific Research to support – Tulving also used brain scans as evidence for the nature of different stores. PET scans found that episodic and semantic memories were associated with the prefrontal cortex. The pre-frontal cortex is in both the left and right hemisphere of the brain. The left pre-frontal cortex was found to be responsible for the semantic memories and the right pre-frontal cortex responsible for episodic memories. It is also thought that procedural memory resides in the cerebellum. This should come as no surprise as the cerebellum (or little brain) has long since been known to be involved in fine motor coordination, necessary in many skills.
Useful applications – Knowing what parts of the brain are responsible for what is really useful in helping those with brain damage. Brain plasticity can help by training other parts of the brain to compensate for the damaged parts. In addition, being able to distinguish between different types of LTM means that specific direction of help can be provided. Belleville et al (2006) found that episodic memory could be improved in older people who have a mild cognitive impairment.
Empirical evidence to support lacks ecological validity – The PET scans carried out by Tulving, may be believed as objective and scientific measures, however, the tasks that are being carried in Tulvings research are artificial, therefore, we cannot be entirely sure that everyday tasks that are carried out in real life, would elicit the same activity in the brain areas stated.
Research to support uses Case studies – Validity – Research into types of LTM is heavily reliant on case studies of brain-damaged patients. Case studies are always difficult to generalise to the general population. By their very nature they are one-offs and in cases of amnesiacs, one-offs with brains that are not typical of the general population. Cause and effect – It can be hard to assume that the brain injury is the only contributing factor to the issues in memory. As there is no information on what the patients memory was like prior to the accident, it is difficult to provide a valid comparison. However, researchers can try to overcome this by talking to family members. This helps to build some sort of baseline for their memory before the accident. However, this is retrospective data and therefore it is not ideal as it may not always be valid information.