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Memory - Coggle Diagram
Memory
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Coding, Capacity, Duration
Coding: format or 'type' of information stored in each memory store
- Acoustic Coding in STM: information stored in STM is primarily acoustically, Baddeley (1966) demonstrated that recalling acoustically-similar words immediately after learning leads to more mistakes
- Semantic Coding in LTM: LTM predominantely encodes information semantically, Baddeley found that recalling semantically-similar words 20 mins after learning them results in more mistakes
Capacity: volume of information can be stored in each memory store
- STM: capacity is estimated to be 7+/- 2 items (based on Miller's research), Jacobs found a mean letter span on 7.3 and a mean digit span of 9.3
- LTM: capacity is believed to be unlimited
Duration: amount of time that information can be stored in each memory store
- STM: information can be stored for 18-30 secs (according to Petersen et al (1959) found that increasing retention intervals decreased the accuracy of recall of conconant syllables in 24 undergraduates when counting down from a 3-digit number (preventing mental rehearsal)
- LTM: duration is unlimited, demonstrated by Bahrick et al who found photo recognition of graduating classmates decreased from 90% to 70% between 15 and 46 years after graduating
Evaluation
- Historical psychological research (e.g. Jacobs) - lack of standardisation and scientific rigor. Potential influence of confounding variables like noise or difficulty of word lists.
- Strength of Bahrick et al (1975) - use of meaningful stimuli and high mundane realism. Findings have ecological validity,
- Limitation of Petersen et al and Miller et al - low mundane realism in methodologies. Use of artificial stimuli limits the generalisation
- Recent research suggests STM capacity may be closer to 4 chunks rather than Miller's original 5-9 estimate. Miller's estimate may have been influenced by outdated methodologies and lack of control over confounding variables
Types of LTM
Episodic Memory:
- Memories with personal meaning, including details of when and how events occurred, and associated with people and places
- Examples: wedding memories, first encounters with a partner
Semantic Memory:
- Memories of general knowledge about the world, including understanding of words, themes and concepts
- Examples: understanding abstract concepts, using information to comprehend new concepts
Procedural Memory:
- Memories of learned skills or procedures, typically performed automatically without conscious effort
- Examples: swimming, driving a car
Evaluation
- Petersen et al - found semantic memories recalled from the left prefrontal cortex, episodic memories recalled from the right prefrontal cortex - indicates different neurological bases for each type of LTM
- Practical applications - Belleville et al noted mild cognitive impairments most commonly effect episodic memories - increased understanding of episodic memory, alongside the differences between types of LTM, may lead to improved, increasingly targeted treatments for mild cognitive impairments
- Cohen and Squire drew a distinction between declarative and non-declarative memories. Declarative have to be recalled consciously (episodic and semantic) and non-declarative can be recalled unconsciously (procedural). Different classification and organisation than Tulving - his depiction of LTM may not be entirely accurate
- Clive Wearing - one type of memory can be impaired (episodic) whilst the others may remain unaffected. Clive Wearing's ability to play piano but unable to remember his wife visiting 5 mins prior (severe episodic memory loss). Confirms classification of LTM types as separate, demonstrates involvement of different brain areas in each type of memory
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