Episodic and Semantic memory

Question 1

When and who proposed the theory of episodic and semantic memory?

Answer 1

Enel Tulving made the first distinction between episodic and semantic memory in 1972.

Question 2

What is episodic memory?

Answer 2

• a “mental diary” retrieving and storing information about experiences or events that occur in our life.
• receives and stores information about dates, times, events - things that relate to the individual.
• can be encoded using visual material, sound, spatial material, smells etc.
• autobiographical - involve the individual and are encoded with personal information.

Question 2

What is encoding and storage?

Answer 2

• Tulving believed episodic memory is stored and encoded according to how it is experienced (encoding and storing what is perceived about the memory as well as the time and space in which it took place).
• people can recall any episodes equally well, regardless of their type.
• episodic memories are stored as they arrive - there is no hierarchy.
• semantic memories are not usually stored with temporal and spatial information.
• the semantic memory system doesn’t seem to be organised according to the time and place of when the memories were encoded.

Question 2

What is semantic memory?

Answer 2

• “mental encyclopaedia” storing words, rules, meaning and concepts.
• needed for language and understanding symbols.
• detached from any temporal link, as factual information can be recalled without reference to when it was learnt.
• they have a cognitive, or thinking, element and are about objects and concepts, unrelated to the individual.

Question 2

What is retrieval?

Answer 2

• retrieving an episodic memory is only possible if it has been encoded and stored.
• semantic memories can help people to work out things they don’t actually know before doing the working out.
• retrieval from semantic memory doesn’t change the actual memory itself, but may mean a new memory is stored.
• retrieval from episodic memory changes the memory that is stored, as a new episode that links to it is encoded and stored.

Question 3

What is the evidence for episodic and semantic memory?

Answer 3

• experiments for episodic memory require recall of a personal episode in a particular time or place whereas experiments on semantic memory look at retrieval processes and is recorded from “free recall” so “right and wrong” is not measured.
• Bower et al (1969) word list experiment showed participants with words in categories recalled more words - evidence for the existence of semantic memory.
• case studies of individuals with brain damage (left hemisphere) suggest prefrontal lobes important to storing new episodic memories.
• Dickerson and Eichenbaum (2010) write about links between episodic memory and the MTL and the hippocampus suggesting these areas play a role in the organisation in memory and encoding memories.

Question 4

What is the evidence for the two separate LTM stores?

Answer 4

• studies of amnesia patients - one store can be affected whilst the other remains intact.
• Ostergaard (1987) - 10 year old boy with brain damage had impairment to both semantic and episodic memory but was later able to store info in his semantic memory whereas his episodic memory still remained affected.
• KF case study - specific impairment to episodic memory from motorbike accident but could still recall a large amount of factual info. Semantic memory still remained intact even though his episodic memory was severely damaged. Also suggests that these individual stores occupy separate regions in the brain.

Question 5

What is procedural memory?

Answer 5

• both HM and CW suffered memory impairments meaning they weren’t able to retain and recall long-term episodic or semantic memories.
• however, HM was able to learn new skills like how to play tennis and CW could remember how to play the piano, indicating a separate long-term store for practised skills.
• as a result, Tulving added procedural memory to his theory of LTM, as an additional store for skills and abilities we learn.

Question 6

What are the strengths of Tulving’s theory of LTM?

Answer 6

• neurophysiological evidence to support there being two categories of memory in LTM e.g. link between damage to areas such as the MTL, prefrontal lobes and more generally the left hemisphere and episodic memories.
• Dickerson and Eichenbaum (2010) review what’s known about episodic memories and neurophysiological evidence and conclude there is evidence for episodic memories.
• lots of detail provided about the two stores and what their differences are e.g. how storage and retrieval is different for each store. His argument is supported with evidence and very thorough.

Question 7

What are the weaknesses of Tulving’s theory of LTM?

Answer 7

• Tulving uses examples of everyday use of memories to explain difference between semantic and episodic memory but this doesn’t tell us the actual difference - descriptive rather than explanatory.
• it’s been suggested the MTL is used for both semantic and episodic memories and it may be there isn’t as much evidence for them being separate stores (e.g. Squire and Zola, 1998). Also, Tulving mentions the two stores rely on one another so they might not be as separate as first thought.
• when undertaking an episodic task, like learning a word list, the two stores work together, making research into the sperate stores problematic as they cannot be studied in absolute isolation from one another.