Long-Term Memory

• Long-term memory (LTM) is the final stage of the multi-store memory model proposed by Atkinson and Shiffrin, providing lasting retention of information and skills
• Theoretically, long-term memory capacity could be unlimited, with the main constraint on recall being accessibility rather than availability
• Duration of long-term memory might range from a few minutes to a lifetime
• Suggested encoding modes for long-term memory are semantic (meaning) and visual (pictorial), but can also be acoustic
• Long-term memory is divided into two types: explicit (knowing that) and implicit (knowing how)
• Episodic memory is part of explicit long-term memory and stores information about events (episodes) experienced in life
• Semantic memory is part of explicit long-term memory and stores information about the world, including knowledge about the meaning of words and general knowledge
• Procedural memory is part of implicit long-term memory and is responsible for knowing how to do things, such as memory of motor skills. It is non-declarative, meaning that it can be recalled without conscious effort.
• Declarative knowledge involves "knowing that" something is the case, for example, knowing that London is the capital of England (e.g. semantic memory).
• Procedural knowledge involves "knowing how" to do things, like playing the piano or riding a bike
• Patients with amnesia have difficulty retaining episodic and semantic information but can recall procedural memories and acquire new skills
• Bahrick et al. (1975) studied very long-term memory (VLTM) and found that long-term memory has a potentially unlimited duration
• Bahrick et al.'s study used meaningful stimuli, testing people's memories from their own lives, which increases external validity
• Bahrick et al.'s study did not control for confounding variables, so real-world applications should be approached with caution
• 𝙏𝙔𝙋𝙀𝙎:

  • episodic
  • procedural
  • semantic
• 𝗘𝗣𝗜𝗦𝗢𝗗𝗜𝗖 𝗠𝗘𝗠𝗢𝗥𝗬:

  This refers to our ability to recall events (episodes) from our lives. It has been likened to a diary or a record of personal daily experiences.

  Episodic memories are 'time-stamped' - you remember when something happened as well as what happened.

  Your memory of a single episode will include several elements (e.g. people, places) interwoven to produce a single memory.

  A conscious effort is needed to recall episodic memories (declarative).

  
  

  Examples of episodic memory:

  • a 16th birthday party
  • breakfast this morning
  • yesterday's psychology lesson
• 𝗣𝗥𝗢𝗖𝗘𝗗𝗨𝗥𝗔𝗟 𝗠𝗘𝗠𝗢𝗥𝗬:

  This is our memory for actions and skills, or basically how we do things. We can recall these memories without conscious awareness or much effort (non-declarative).

  These are the sorts of skills that we may find difficult to explain to somebody else.

  
  

  Examples of procedural memory:

  • knowing how to ride a bicycle
  • knowing how to swim
  • knowing how to make a cup of tea
• 𝗦𝗘𝗠𝗔𝗡𝗧𝗜𝗖 𝗠𝗘𝗠𝗢𝗥𝗬:

  This store contains our shared knowledge of the world. It has been likened to a combination of an encyclopaedia and a dictionary. The semantic memory contains an impressive knowledge of concepts, e.g. the meaning of words.

  These memories are not time-stamped and are less personal.

  It is declarative as it must be recalled consciously.

  Tulving suggests it is less vulnerable to distortion and forgetting than episodic memory.

  
  

  Examples of semantic memory:

  • knowing that Paris is the capital of France
  • knowing that the number 3 is between the numbers 2 and 4
• Endel Tulving (1985) was one of the first cognitive psychologists to realise that the multi-store model's representation of LTM was too simplistic and inflexible.

  He proposed that there are in fact three LTM stores containing very different types of information: episodic, procedural, and semantic.
• EPISODIC MEMORY: A long-term memory store for personal events. It includes memories of when the events occurred and the people, places, objects, and behaviours involved. Memories from this store have to be retrieved consciously and with effort.
• SEMANTIC MEMORY: A long-term memory store for our knowledge of the world. This includes facts and our knowledge of what words and concepts mean. These memories usually also need to be recalled deliberately.
• PROCEDURAL MEMORY: A long-term memory store for our knowledge of how to do things. This includes our memories of learned skills. We usually recall these memories without making a conscious or deliberate effort.
• 𝙀𝙑𝘼𝙇𝙐𝘼𝙏𝙄𝙊𝙉:

  1. clinical evidence (HM and Clive Wearing)
  2. lack of variable control (counterpoint to clinical evidence)
  3. conflicting neuroimaging evidence (Buckner and Peterson, Tulving)
  4. real-world application (Belleville et al.)
  5. same or different (Tulving)
• 𝟭. 𝗖𝗟𝗜𝗡𝗜𝗖𝗔𝗟 𝗘𝗩𝗜𝗗𝗘𝗡𝗖𝗘:

  One strength is evidence from the famous case studies of HM and Clive Wearing.

  Episodic memory in both men was severely impaired due to brain damage (operation and infection respectively), but their semantic and procedural memories were relatively unaffected.

  They understood the meaning of words, could walk and speak, and Clive Wearing (a professional musician) could play guitar.

  This evidence supports Tulving's view that there are separate memory stores in the LTM - one can be damaged and the others unaffected.
• 𝟮. 𝗖𝗢𝗨𝗡𝗧𝗘𝗥𝗣𝗢𝗜𝗡𝗧 𝗧𝗢 𝗖𝗟𝗜𝗡𝗜𝗖𝗔𝗟 𝗘𝗩𝗜𝗗𝗘𝗡𝗖𝗘:

  Clinical studies of brain injuries can help researchers to understand how memory is supposed to work normally, however a major limitation is that they lack control of variables.

  For example, brain injuries are unexpected and the researcher has no control over what happens to the participant before/during the injury, or knowledge of the individual's memory before the damage to judge if it is worse afterwards.

  This lack of control limits what clinical studies can tell us about different types of LTM.
• 𝟯. 𝗖𝗢𝗡𝗙𝗟𝗜𝗖𝗧𝗜𝗡𝗚 𝗡𝗘𝗨𝗥𝗢𝗜𝗠𝗔𝗚𝗜𝗡𝗚 𝗘𝗩𝗜𝗗𝗘𝗡𝗖𝗘:

  One limitation is that there is conflicting research linking types of LTM to areas of the brain.

  Buckner and Peterson (1996) reviewed evidence of the location of S. and E. memory. They concluded that S. memory is located on the left of the prefrontal cortex and E. memory on the right.

  However, other research links the left with E. encoding and the right with E. retrieval (Tulving et al.).

  This challenges any neurophysical evidence to support types of memory as there is poor agreement on where each type is located.
• 𝟰. 𝗥𝗘𝗔𝗟-𝗪𝗢𝗥𝗟𝗗 𝗔𝗣𝗣𝗟𝗜𝗖𝗔𝗧𝗜𝗢𝗡:

  Another strength is that understanding types of LTM allows psychologists to help people with memory problems.

  For example, as people age, they experience memory loss. But research has shown this to be specific to episodic memory - recent memories become hard to recall though past ones remain intact.

  Belleville et al. (2006) aimed to improve episodic memories in older people. Those she trained performed better on the test than the control group.

  This shows that distinguishing between LTM types enables specific treatments to be developed.
• 𝟱. 𝗦𝗔𝗠𝗘 𝗢𝗥 𝗗𝗜𝗙𝗙𝗘𝗥𝗘𝗡𝗧:

  More recently, Tulving (2002) has taken the view that episodic memory is a 'specialised subcategory' of semantic memory (essentially the same store).

  His research showed that some people with amnesia have a functioning semantic memory alongside a damaged episodic memory, but it is not possible to have a functioning episodic memory with a damaged semantic memory.

  However, Hodges and Patterson (2007) found that some people with Alzheimer's disease (a type of dementia) could form new episodic memories but not semantic memories.
• Tulving (2002) now suggests E. memory is a ‘specialised subcategory’ of S. memory (the same store). He found it is possible to have a fully functioning S. memory with a damaged E. memory. However, he concluded it is impossible vice versa.

  Hodges and Patterson (2007) found that some people with Alzheimer’s could form new E. memories but not S. memories (semantic dementia). This suggests that E. memory does not require a functioning S. memory and therefore must be separate.

  This evidence shows that episodic and semantic memories are closely related but ultimately different forms of LTM.
• • Episodic: LTMs of events/experiences in our lives, likened to a diary. Time-stamped, have to be consciously recalled.

  
  

  • Semantic: LTMs of our knowledge of the world, likened to a combination of a dictionary and an encyclopaedia. Not time stamped, more complex than just 'facts'.

  
  

  • Procedural: LTMs of skilled behaviours such as driving a car. Trying to explain them may make task more difficult.
• Information stored with reference to time and place refers to episodic memory.
• Information not available for conscious inspection refers to procedural memory.