Memory

• Memory

  Human memory can broadly be defined as the process by which we return information about events that have happened in the past
• Short term memory 


  • Information disappears unless rehearsed
  • Rehearsal is attending to information so it stays in your memory, eg verbally repeating it over and over again
• Coding:


  Information that we store has to be written in memory in some form. It is described as a code in which it is held in the form of sound (acoustic), images (visual) or meaning (semantic)
• Baddeley's experiment on Coding 


  Baddeley gave 4 different lists of words to 4 gorups of participants to remember:

  1. acoustically similar, words that sounded similar
  2. acoustically dissimilar, words that sounded different
  3. semantically similar, words with similar meaning
  4. semantically dissimilar, words that all hold different meaning

  Participants recalled the words immediately and 20 mins after (short term and long term)
• Baddeley's results on Coding 


  • He found that participants had difficulty remembering acoustically similar words in the STM, but not in the LTM
  • Semantically similar words posed little problem for the STM but led to the LTM getting muddled
  • Suggests that STM is coded acoustically
  • LTM is coded semantically
• Capacity of the short term memory 


  Can be assessed using digit span task
• Jacobs (1887)


  • Developed the digit span task
  • Process: Researcher gives participants (for example) 4 digits and asks participant to recall digits back
  • The number of digits needed to recall back increases each time
  • Digit span is when the participant can no longer recall the numbers back
• Jacobs (1887) results


  • Found that the average span for digits was 9.3 items and the average span for letters was 7.3
  • Jacobs suggested it was easier to remember digits as there are only 9 in comparison to 26 letters
• Chunking:

  Grouping sets of digits or letters into chunks to make it easier to remember
• Miller


  • He suggests that the capacity of STM is about 7 items (plus or minus 2)
  • He found that people can count 7 dots flashed onto a screen but not many more
  • Miller notes that people can recall 5 words as well as they can recall 5 letters due to chunking
• The Duration of STM experiment, process


  • Peterson and Peterson (1959) tested 24 undergraduate students
  • Each participants took part in 8 trials
  • Each trial: student was told a consonant syllable (a trigram) such as YCG to remember and also given a 3 digit number ( eg 493)
  • Told to recall the consonant syllable after a retention interval of 3,6,9,12,15, and 18 seconds
  • During retention interval, they had to count backwards from the 3 digit number until told to stop (to prevent rehearsals)
• Duration of long term memory experiment

  Bahrick et al (1976) studied 400 participants from America aged 17-74: High school year books were obtained Recall was tested in various ways Examples:

  • Photo recognition
  • Free recall
• Bahrick, photo recognition


  Participants who were tested within 15 years of graduating were about 90% correct

  After 48 years, recall declined to about 70%
• Bahrick, free recall


  Participants after 15 years were 60% accurate

  After 48 years, 30% accurate
• Bahrick results


  Shows the LTM lasts a long time but decreases
• Multistore model of memory

  1. Environmental stimuli
  2. Sensory register
  3. Attention
  4. Short term memory
  5. Maintenance Rehearsal
  6. Prolonged rehearsal
  7. Long term memory
  8. Retrieval
  9. Short term memory
• 3 multistore model of memory stores

  1. Sensory register
  2. Short term memory
  3. Long term memory
• 5 multistore model of memory processes


  1. Environmental stimuli
  2. Attention
  3. Maintenance rehearsal
  4. Prolonged rehearsal
  5. Retrieval
• Sensory register

  Capacity:

  Very high capacity

  Duration:

  Visual, half a second

  Auditory, 2 seconds
• Short term memory

  Capacity

  5-9 items

  Duration

  18-30 seconds
• Long term memory

  Capacity

  Unlimited

  Duration

  Unlimited
• Maintenance Rehearsal


  To keep information in STM

  Rehearsed/repeated in a loop
• What is a model?

  A model is a representation of something to explain how it works
• What is the multistore model?

  A representation of how memory works in terms of three stores. It also describes how information is transferred from one store to another, how it is remembered and how it is forgotten
• Who proposed the model?

  Attinson and Shiffrin suggested that memory is made up of three stores, linked by processing
• Environmental stimuli 


  Information from the environment that enters the brain via the senses
• Attention


  Selectively concentrating on a piece of information
• Prolonged rehearsal 


  Continuous repetition of information moving a memory from the STM to the LTM
• Retrieval 


  Getting information from the LTM back from the STM so it can be recalled
• Sensory register 


  • One store for each of our senses
  • 2 main stores: iconic memory (visually) and echoic memory (acoustically)
  • Very high capacity (over 100 million cells in one eye storing data)
• Short term memory 


  • If you pay attention to it, what goes into the sensory register will pass into the memory system (if not you will forget it, it will decay/memory trace dies out)
  • Coded acoustically
  • lasts about 18-30 seconds
  • limited capacity store of 5-9 items
  • Unless rehearsal takes place, forgetting will occur
• Short term memories are forgotten due to

  • Memory trace decay
  • Displacement
• Long term memory


  • Permanent store for information
  • Potentially unlimited capacity
  • Info may be lost due to displacement, retrieval failure, interference etc (not because of a limited capacity)
  • Info is stored in the LTM but when we want to recall it , info is transferred to the STM through the process of retrieval
  • Coded semantically
  • MSM does not break down the LTM stores for each of these memory types
• What is the working memory model?

  The working memory model is an explanation of how STM is organised and how it functions. The WMM is concerned with the part of the mind that is active when we are temporarily storing and manipulating information.
• Who proposed the WMM?

  Baddely and Hitch 1974
• 4 main components of the WMM

  • Central executive
  • Phonological loop
  • Visuo-spatial sketchpad
  • Episodic buffer
• Central Executive

  • Supervisory role
  • Responsible for monitoring, coordinating, problem solving, decision making and reasoning
  • Operator of the slave system
  • Capacity: limited
  • Coding: Modality free
• Visuo-spatial sketchpad


  • Deals temporarily with visual and spatial information
  • Inner eye
  • Professor Logie: Visual cache, Inner scribe
  • Capacity: 3-4 objects
  • Coding: Visual
• Phonological loop

  • Phonological store (inner ear)-> spoken words enter the store directly for 1-2 seconds before it fades
  • Articulatory process (inner voice)-> words must be converted into a spoken code before entering the phonological loop, allows maintenance rehearsal
  • Capacity: 2 seconds worth of information
  • Coding: acoustically
• Episodic buffer


  • Only recently added (2000)
  • More of a general store
  • A temporary capacity store that binds verbal, visual and spatial information