Memory

• Coding


  The format in which information is stored
• Capacity


  The amount of information that can be held in a memory store
• Duration


  The length of time information can be held in memory
• Short term memory (STM)

  • Limited capacity store
  • Coding is mainly acoustic (sound)
  • Capacity is about 5 to 9 items on average
  • Duration is between 18 and 30 seconds
• Long term memory (LTM)


  • The permanent memory store
  • Coding is mainly semantic (meaning)
  • It has unlimited capacity

  
• Alan Baddeley (1966) experiment


  1. Gave different lists of words to four groups of participants to remember

  2. Acoustically similar words

  3. Acoustically dissimilar words

  4. Semantically similar words

  5. Semantically dissimilar words

  6. Participants were asked to recall the words in correct order
• When recalling words immediately after hearing (STM recall)


  Participants tended to do worse with the acoustically similar words
• When recalling words after a 20 minute interval (LTM recall)


  Participants did worse with the semantically similar words
• Strengths of Jacobs (1887) research

  • Lab experiment
  • High control over extraneous variables
  • High internal validity
• Weaknesses of Jacobs (1887) research

  • Extremely artificial tasks
  • Low mundane realism
  • Ungenralisable
• Jacobs (1887) found the mean span for digits was 9.3 items and for letters was 7.3
• Jacobs (1887) sample was 443 female students age 8-19 from one school
• Memory span and chunking

  • Miller (1956) noted that the span (or capacity) with STM is about 7 items plus or minus two
  • People can recall 5 words as well as 5 letters by chunking - grouping sets of digits or letters into units or chunks

  
• Strengths of Peterson and Peterson (1959) research

  • Lab study
  • High levels of control
  • High internal validity
  • High ability to replicate
• Weaknesses of Peterson and Peterson (1959) research

  • Done on psych undergrads
  • High demand characteristics
  • May already know about the MSM
  • Cannot be generalised
  • Low ecological validity
  • Use of trigrams not used in everyday
• Strengths of Bahrick et al (1975) research


  • High levels of ecological validity
  • Uses real life memory's
  • Can be applied t everyday human memory

  
• Weaknesses of Bahrick et al (1975) research


  • Sample is all uni grad students
  • May not be able to be generalised to other populations or cultures
  • Doesn't state why LTM becomes less accurate over time
• Multi store memory model (MSM)

  • A representation of how memory works, proposed by Atkinson and Shiffrin (1968, 1971)
  • Proposes three stores: sensory register, STM and LTM
  • Shows how information flows through the memory system

  
• Maintained rehearsal


  Occurs when we repeat material over and over, passing it from the STM to the LTM
• Retrieval


  When information is wanted from the LTM it has to be transferred from the LTM to the STM by a process of retrieval
• Stores, Coding, Capacity, Duration

  • Sensory register: Iconic - visual, Echoing - acoustic, Huge capacity, Less than half a second duration
  • STM: Acoustically coded, 7 +/- 2 capacity, Very short duration
  • LTM: Semantically coded, Unlimited capacity, Permanent duration
• Episodic LTM


  • Stores personal events, memories of people, objects, places and behaviours, memories are timestamped and have to be retrieved consciously
• Semantic LTM


  • Stores knowledge of the world, including facts and meanings of words and concepts, recalled deliberately and not timestamped
• Procedural LTM


  • Stores how to do things, includes memory and learned skills, recalled without conscious or deliberate effort
• Working memory model (WMM)

  A representation of short-term memory (STM), suggests STM is a dynamic processor of different types of information using sub-units coordinated by a central decision-making system

  
• Components of the WMM

  • Central executive - coordinates the activities of the three subsystems and allocates processing resources
  • Phonological loop - processes information in terms of sound, including written and spoken material
  • Visuo-spatial sketchpad - processes visual and spatial information
  • Episodic buffer - brings together material from the other subsystems into a single memory and provides a bridge between working memory and long-term memory

  
• Interference


  Forgetting because one memory blocks another, causing one or both memories to be distorted or forgotten
• Proactive interference (PI)


  Forgetting occurs when older memories disrupt the recall of newer memories, greater when the memories are similar
• Retroactive interference (RI)


  Forgetting occurs when newer memories disrupt the recall of older memories, greater when the memories are similar
• McGeoch and McDonald's retroactive interference study

  1. Participants learned a list of words to 100% accuracy, then learned a new list of different types (synonyms, antonyms, unrelated words, nonsense syllables, 3-digit numbers, or no new list)

  2. Recall of the original list depended on the nature of the second list, with the most similar material (synonyms) producing the worst recall
• Retrieval failure


  A form of forgetting where the memory is available but not accessible unless a suitable cue is present
• Cue


  A trigger of information that allows us to access a memory
• Encoding specificity principle


  Proposed by Tulving, states that a cue has to be present at both encoding and retrieval to help recall information
• Godden and Baddeley (1975) study on context-dependent forgetting


  1. Deep sea divers learned a list of words either underwater or on land, then recalled the words either underwater or on land

  2. Accurate recall was 40% lower when the learning and recall contexts did not match
• Carter and Cassaday (1998) study on state-dependent forgetting


  1. Participants learned lists of words and passages while on an anti-histamine drug, then recalled the information either on or off the drug

  2. Recall was better when the drug state matched between learning and recall
• Procedure


  1. Learn on land - Recall on Land

  2. Learn on land - Recall underwater

  3. Learn underwater - Recall on Land

  4. Learn underwater - Recall Underwater
• In two of these conditions the environmental contexts of learning and recall matched whereas in the other two they did not
• Accurate recall was 40% lower in the non-matching conditions
• The external cues available at learning were different from the ones at recall and this led to retrieval failure
• Procedure


  1. Learn on drug - recall when on it

  2. Learn on it - recall when not on it

  3. Learn not on drug - recall when not on it

  4. Learn not on it - recall when not on it