Define LTM
Long-term memory is the stage of the dual memory model proposed by the Atkinson-Shiffrin memory model where informative knowledge can be stored for long periods of time. Previous models proposed it as a unitary store model, whilst more recent models seem to suggest that it comprises of a number of subsystems.
What is explicit/ declarative memory?
Declarative (explicit) memory involves conscious recollection of facts and events
What is implicit memory
does not involve conscious recollection
Where did evidence of the distinction between non-declaritive and decalritive memory systems come from?
- amnesic patients - For example HM (reported by Scovile and Milner, 1957) was shown to have extremely poor declarative memory but was able to learn procedural tasks such as mirror tracing, pursuit rotor and perceptual identification (which did not involve conscious recollection).
- functional neuroimaging studies - showed that the areas associated with declarative and non-declarative memory are different both at times of encoding and retrieval and associated with different levels of activation at retrieval. Increased brain activation was associated with declarative memory and decreased activation was associated with non-declarative.
Who argued that argued that there were two kinds of memories within declarative memories itself?
Tulving (1972)
what are episodic memories?
involve the storage and retrieval of specific events or episodes occurring in a given place or time.
what are semantic memories?
Involve the storage and retrieval of ideas and concepts that are not drawn from personal experience e.g. general knowledge about concepts, language and so on.
Where does evidence for the distinction between episodic and semantic memories come?
- amnesics - Earlier studies showed how many amnesics appeared to be selectively impaired in their ability to recall episodic memories, whilst showing little impairment in their ability to recall semantic knowledge.
- brain imaging - more convincing evidence comes from neuroimaging studies, which have shown that semantic and episodic recall tasks produce activation in different areas of the brain. It has been found that recall of semantic knowledge produces activation primarily in the left temporal lobe, whilst recall of contextual episodes causes citation in the right prefrontal area (Buckner, 2000)
who distinguishes between non-declaitive sub-types?
Schatecer et al (2000)
What are the two distinctions in the non-declarative memory systems?
- the perceptual representation system or priming (cognitive) - (neocortex) a collection of domain-specific modules that operate on perceptual information about the form and structure of words and objects (priming)- exposure to a stimulus influences response to a later stimulus repetition.
- procedural memory. (behavioural) - (striatum / motor cortex) refers to the learning of the motor and cognitive skills such as reading or riding a bike.
how is LTM measured (in general)?
When measuring long-term memory, there are a number of ways to do so, depending on what area of long-term memory you aim to measure. The direct methods of assessing memory are: (i) recall, (ii) recognition, (iii) relearning, and (iv) reconstruction. The indirect method focuses on the amount of transfer of previous learning to a subsequent learning situation.
how is explicit memory measured?
Recall and recognition tasks, or cued recall.
This includes things like:
- Object naming (“ This is a picture of …..”)
- Queries about word knowledge e.g:
- the pyramids and palm trees experiment, in which participants decide what type of tree is most associated with the Egyptian pyramid).
- Synonym generation tasks, in which individuals must name as many categories in 1 min, have also been used to evaluate fluency and speed of accessing categories of information.
- The Weshler memory scale (WMS- 111) uses story recall, face recognition, impaired word associations, word lists and figure drawing to test explicit long-term-memory.
how is implicit LTM measured?
For implicit memory, measures are taken of action rather than recollection.
- Procedural tasks can be tested by rotor pursuit tasks and mirror tracing procedures.
- priming tasks can take the form of repetition priming tasks (e.g. Gollins figure test, word completion for rare words and homonym definitions) and semantic priming tasks (e.g lexical decision tasks).
what considerations need to be made when measuring specific aspects of LTM?
one important consideration however when testing LTM is that lower order disruptions (for example implicit long term memory failure) can disrupt higher order functions (e.g. episodic and semantic explicit memory).
How is explicit memory used in communication?
- storage and retrieval of words and their meanings in semantic memory.
- understand words and thier meaning
- speed - find words at an approproate speed
- follow instructions and conversations
- storage and retreival of facts, events and names in episodic memory
- improve understanding and resolve ambiguity
- pragmatic meaning
- manner
- build social relationships
- topic
How is non-declaritive memory used in conversations?
how does explicit memory help us improve understanding and resolve ambiguity?
how does explicit memory help us understand pragmatic meaning?
