Memory AS Level revision.

• Memory is the process of retaining information for some time after it is learned. There are three stages in memory – encoding, storage and retrieval. 

  Encoding: translating information into a form that the brain can use. This is the first stage in memory. 

  Storage: encoded memories must be stored somewhere in the brain.

  Retrieval: there must be some way of accessing stored memories. 
• According to the multi-store model of memory (MSM), information to be remembered flows through a series of three stores:
• Sensory register (SR) – the impression of the world taken in by your senses.
• Short-term memory (STM) is the kind of memory where you ‘hold something in your mind’ for a few seconds.
• Long-term memory (LTM) includes all our permanently stored knowledge and experience.
• The stores differ in terms of their coding, capacity and duration.
• Coding: - STM=acoustically -LTM= semantically -SR= sesnory traces
• Capacity: - STM= 7+-2 -LTM=very large - SR= 10 items
• Duration: -STM= 18-30 seconds -LTM= a lifetime -SR= <2seconds
• Coding is the format in which the information is stored. 

  Capacity is the amount of information that can be held in each store. 

  Duration is the length of time that information can be retained in this store.
• Procedure


  1. Participants were asked to recall either acoustically-similar words (e.g. map, man, mad) or semantically-similar words (e.g. great, big, large)

  2. Their recall was tested either immediately (STM condition) or after a 20 minute gap (LTM condition)
• Coding in Sensory Register

  Coding in SR depends on the sense organ that the information comes in through, as the code is simply a representation of the physical properties of the stimulus.

  visual = iconic memory

  hearing = echoic memory

  touch = haptic memory
• Capacity in Long-term memory: Luria (1964)

  The capacity of LTM is hard to measure, because it seems to be practically unlimited. Support for this view comes from case studies of mnemonists (people who have extraordinary memories). One example is Solomon Shereshevsky, a Russian journalist, who was studied over many years by the psychologist Luria. 
• Capacity in Short-term memory

  Immediate memory span
• Procedure


  1. The researcher read lists of numbers or letters to Ps of different ages, who were instructed to repeat the list back in the correct order

  2. The researcher increased the length of the list until P could only recall correctly 50% of the time
• STM


  • Limited capacity of between 5 and 9 items
  • Capacity increases with age
• Miller (1956) reviewed the research, and concluded that 'the magic number 7, plus or minus 2' was the capacity of STM
• Chunking


  A technique to increase the capacity of STM
• This is supported by other research that shows limited capacity of STM
• Duration in Short-term Memory

  The length of time information can be retained in short-term memory
• Procedure


  1. P briefly shown a CONSONANT TRIGRAM

  2. P asked to count backwards in 3s (to stop rehearsal)

  3. After intervals of 3, 6, 9, 12, 15 or 18 seconds, P asked to recall the trigram

  4. This procedure was repeated for several different trigrams
• Long-Term Memory


  Memory that lasts for a very long time, potentially a lifetime
• Recognition


  Matching names to faces
• Recall


  Simply naming old classmates
• Capacity and duration in sensory register

  Sperling (1960)
• Procedure


  1. Ps were presented (for less than 1/20 second) with a 3x4 grid of letters and numbers

  2. Ps were asked to recall the characters
• The multi-store model (Atkinson and Shiffrin) is a cognitive model which describes how memory passes through our cognition
• • Physical stimuli from the environment are received into the sensory register. 
  • The information that we pay attention to will pass into our short term memory. The rest decays away. 
  • If we want to keep something active in short term memory, we use maintenance rehearsal.
  • Information is passed to permanent storage in long-term memory via elaborative rehearsal. 
  • Retrieval involves bringing memories from short term memory to long term memory where they can be experienced and acted upon. 
  • Each store differs in terms of coding, capacity and duration, as above. 
• features of the MSM: -

  • structural model
  • STM and LTM are unitary stores
  • Information is passed in a linear pathway
  • Rehearsal is needed to pass information from STM to LTM
  • each store has its own features for encoding, capacity and duration
  • Each stores explanation for forgetting is different.
• Evaluation of the multi-store model

  + The research detailed above all supports the multi-store model, by showing that it accurately describes how some aspects of memory work in real life (for example, showing that there really are two separate memory stores, which can be distinguished in terms of encoding, capacity and duration. 
• Evaluation of the multi-store model+ Another line of support comes from clinical evidence from cases of amnesia:

  • Patient ‘HM’ was not able to form any new long-term memories after surgery for epilepsy destroyed his hippocampus, but retained some STM function.
  • Patient  ‘KFA’ had impaired STM but intact LTM following a head injury sustained in a motorcycle crash. 
• Evaluation of the multi-store model:  However, STM is not a unitary store - but the research by Baddeley (see below) shows that STM is much more complex than the model suggests, and deals with auditory and visual information separately.  Thus the working memory model is a more accurate description of STM. 
• Multi-store model


  • LTM is more complex than this model allows
  • Tulving (1972) distinguished between semantic, episodic and procedural LTM
• Elaborative rehearsal


  A strength of the multi-store model is that it has clear implications for improvement of ordinary memory
• In practice, memory improvement strategies based on rehearsal are not very helpful, compared to ones based on visualisation or organisation
• The multi-store model overemphasises the importance of rehearsal
• Episodic LTM

  This is autobiographical memory, which enables us to re-experience events that have happened to us. It does not work like a video recorder, but instead is constructive, and therefore prone to many errors and illusions. It is a form of declarative, or explicit memory, which means it can be consciously recalled.
• Semantic LTM

  This is another form of declarative memory, which is concerned with facts and knowledge. For example, knowing that World War I began in 1914.

  The case study of amnesic patient KC (studied by Endel Tulving) demonstrates the distinction between episodic and semantic memory. After a motorcycle accident, he was unable to recall any events from his own life (episodic memory was impaired) while his semantic memory, including his knowledge of facts about his own life was intact. 

  There is a link between semantic and episodic memories, as semantic memories begin as episodic ones. 
• Endel Tulving


  One of the first researchers to use cognitive neuroscientific neuroimaging techniques to understand cognitive functions in the brain
• Experiment procedure


  1. 6 volunteers given injections of radioactive gold

  2. Presence of substance detected with gamma-ray detector

  3. Participants asked to think about autobiographical events (episodic condition) or learned facts (semantic condition)