Models of Memory

Models of memory 

What is memory? 

Memory is defined as the ‘mental process of encoding, storing and retrieving information.’

Types of Memory

  1. Declarative: (“knowing what”) is the memory of facts and events, and refers to those memories that can be consciously recalled. Two subset of declarative memory:

  • Episodic memory: contains the memory of specific events that have occurred at a given place and time

  • semantic memory: general knowledge and facts and people, not linked to time and place

  1. Procedural memory: (“knowing how”) unconscious memory of skills and how to do things 


Multi-store model of memory 

  • Consists of three memory stores:

  1. sensory memory (SM)

  2. Short term memory (STM)

  3. long term memory (LTM)

What does each stage of memory do? 


sensory memory: 

  • Duration: ¼ to ½ second

  • Capacity: all sensory experience 

  • Encoding: sense specific (eg: different stores for each sense) 

  • Information comes from the five senses 

  • Sensory information enters through sensory memory 

  • Holds vast amount of information for a fraction of a second 

  • Filters our useless information, allowing us to focus on important details

Short term memory: 

  • Duration: 0-18 seconds (can be extended to 30 seconds) 

  • Capacity: 7 +/- 2

  • Encoding: mainly auditory 

  • Information is lost through displacement or decay 

long term memory: 

  • Duration: unlimited 

  • Capacity: unlimited 

  • mainly semantic (can be visual and auditory)

  • information can be recalled, transferred from STM to LTM when needed 

Clive Wearing by sacks (2007)

Background: 

  • Clive wearing british composer, 

  • mid forties developed viral infection (encephalitis) 

  • left serious brain damage causing memory impairment (retrograde and anterograde amnesia)

Aim: 

  • research what aspects of memory were impaired and what parts of brain damaged

Method:

  • Neuropsychological tests: IQ tests, verbal fluency tests, digit spna tests) testing LTM and STM

  • Interviews

  • Observations 

  • MRI scan

Results: 

  • Clive's memory lasts 7-30 seconds

  • Unable to form new memories

  • Cannot transfer from LTM to STM

  • Semantic and episodic memory damaged

  • Procedural memory intact: can still play piano

Conclusion:

  • Supports MSM

  • STM and LTM are separate

  • STM has limited duration 



Video notes: 

  • Headache leading to memory loss

  • Anterograde amnesia- unable to keep and make memories

  • Retrograde amnesia- can't remember old things

  • Cant take long term to short term memory

  • Can style play music, from procedural memory

  • Keeps diary stating love for wife, writing her name

  • Constantly living in the same moment 

  • Very emotional behaviour, can be from constant confusion or brain problems


The working Memory Model

  • Baddely and Hitch (1974)

  • Building on Atkinson and Shiffrin’s research

  • More complex than MSMM

  • You cannot perform two tasks that use the same woking memory component 

Central executive: 

  • Controls attentional process 

  • Enables working memory system to attend to SOME stimuli but ignore others 

  • Derives info from sensory or LTM and sends to sub-systems: phonological loop and visuospatial sketchpad 

  • Monitors and coordinates other systems

  • Responsible for cognitive tasks like: problem solving, decision making and mental arithmetic 

Phonological loop: 

  • Process for auditory information (spoken or written)

  • Two subcomponents: 

    • Phonological store: inner ear, stores heard information, 1-2 seconds

    • Aticulary process: inner voice, keeps information in phonological loop through rehearsal,

  • When we repeat information we can retain it in the working memory

Visuospatial sketchpad: 

  • Inner eye: spatial and visual information

  • Spatial: where things are, keeping rack of where we are, in relation to surroundings

  • Displays and manipulates visual and spatial information from LTM 

Episodic Buffer

  • Added 2000

  • Facilitates communication between LTM and central executive



Baddely and Hitch (1976)

Aim: to investigate if different components of working memory can be used at the same time

Method: conduct a dual task technique experiment: small sample of students, stirling university, complete two tasks at the same time: digital-span task (repeat a list of numbers) AND verbal reasoning task ( true or false to various questions) 

Results: as number of digits increased students took longer to answer verbal reasoning task (only by fractions of a second) but no more errors were made in verbal reasoning as digits increased

Conclusion: verbal reasoning: central executive, Digital span: phonological loop, supports WMM