STM + LTM

• Coding

  How information is processed - acoustic (sound) (STM) and semantic (meaning) (LTM)
• Duration

  Length of time information can be held in memory
• Capacity


  Amount of information held in memory
• Short term memory

  Information we process and recall straight away
• The digit span test - developed by jacobs:

  Researcher gives number of digits and participant has to recall them in order

  Researcher then increases amount by 1 digit and participant has to recall again until they cannot recall the correct order

  This determines their digit span

  The mean for participant was 9.3 items and 7.3 letters
• We are able to remember 5-9 chunks of information rather that 5-9 single digits. In this way we store more information.
• Cognitive psychology

  Cognitive psychologists believe that human behaviour can be best explained if we first understand the mental processes that underlie behaviour

  Therefore it the study of how people learn, structure, store and use knowledge - essentially how people think about the world around them
• Human memory can mostly broadly be defines as the process by which we retain information about events that have happened in the past
• Retrieval 


  Process of locating and extracting stored memory
• Capacity of memory - george miller:

  Conducted similar experiment argued most things come in 7s

  Concluded that on average we can recall 7 items

  (7 plus or minus 2) range between 5-9 items
• Short term memory

  Information we process and recall straight away

  Stores info we currently aware of
• Long term memory

  The permenant memory store

  Continually storage of info which is largely outside of awareness, recalled when needed. If attend long enough to information in you STM, it can be transferred to LTM

  Coding in this memory store is 'semantic' - eg, for meaning

  LTM has potentially unlimited capacity and can hold info for years until we want to retrieve it
• Differences between STM and LTM

  • LTM is permenant memory store, STM is we process and recall straightaway
  • Capacity: LTM - potentially unlimited, STM - 5-9 items
  • Duration: LTM - forever, STM - 18-30 seconds
  • Encoding: LTM - semantic (baddeley), STM - acoustic (baddeley)
• peterson & peterson (1959) duration STM

  method:

  research method: lab experiment

  participants: 24 students - each were tested over eight trials

  procedure:

  1. on each trial a participant was given a consonant syllable and 3-digit number (eg, THX 512)
  2. were asked to recall consonant syllable after a retention interval of 3, 6, 9, 12, 15 or 18 secs
  3. during retention interval, had to count backwards from their 3-digit number.
• p&p continued

  results:

  on average participants were 90% correct after 3 seconds, 20% correct after 9 seconds, 2% correct after 18 seconds

  conclusion:

  this suggests that the STM has a very short duration - less than 18 seconds - as long as verbal rehearsal is prevented.
• p&p strengths

  • We remember trivial things in everyday life - has some applicability eg, shopping lists
  • Lab study: variables controlled - measuring DV - reliability, internal validity
• p&p weaknesses

  • task is artificial/trivial - lacks ecological validity
  • interference task is not representative in everyday life
  • results may be due to 'displacement'
• baddeley (1966) encoding STM and LTM 


  method:

  acoustic and semantic coding:

  words acoustically similar but semantically different: cat, cab, can, cad, mad, max, mat, man, map

  words opposite - semantically similar but acoustically different: great, large, big, huge, broad, long, tall, fat, wide, high

  alan baddeley used word lists like those above to test effects of acoustic an semantic similarity on STM and LTM.
• baddeley: results and conclusion


  results:

  found that participants had difficult remembering acoustically similar words in STM but not in LTM. whereas, semantically similar words posed similar words, little problems for STM but led to muddles LTMs.

  conclusion:

  this suggests that STM is largely encoded acoustically whereas LTM is largely encoded semantically.
• baddeley: strengths

  • lab study: control of variables, high internal validity - reliability
  • some relevance to coding task in everyday life.
• baddeley: weaknesses

  • not really testing LTM (20 mins)
  • lab study - everyday life we cannot control all variables - lacks ecological validity
• Bahrick (1975) duration LTM

  method:

  participants: 400 people of various ages (17-74) - tested on their memory of classmates

  research method: lab experiment

  procedure:

  1. photo recognition test of 50 photos from participant's high school yearbook
  2. in a free recall test participants were asked to list names they could remember of those in their graduating class
• bahrick: results and conclusion

  results:

  participants who were tested with 15 years of graduation were about 90% accurate in identifying faces. after 48 years, this declined to about 70% for photo recognition.

  conclusion:

  free recall was about 60% accurate after 15 years, dropping to 30% after 48 years.
• bahrick: strengths

  • replicable so results are reliable
  • high external validity - real life meaningful memories were studied
  • ethical
• bahrick: weaknesses

  • culture bias - only americans
  • low ecological validity
  • high demand characteristics
  • cofounding variables are not controlled = they could have looked back at the yearbook and rehearsed the memory over the years
• sperling (1970)

  conducted an experiment which participants saw a grid of digits for 50 milliseconds. they were either asked to write down all 12 items or hear tone immediately after and would recall that particular row.

  theoretically participants should been able to remember 4 items from a row but approx. 3 were remembered.

  this suggests that sensory memory cannot hold info for long

  • info decays rapidly in sensory store
  • supports existence of sensory store
• glanzer and cuntiz (1966)

  showed participants a list of 20 words presented one at a time and then asked to recall

  this is called the serial position effect:

  '' when asking people to remember a list of words which is greater than the capacity of STM - have tendency to remember words from start and end of the list
• primacy effect

  tendency for people to remember first 5 words or so from beginning of the list
• recency effect


  the tendency for people to remember last 5 or so words from end of list
• primacy effect occurs because first words are best rehearsed and transferred to LTM

  recency effect occurs because these are last words to be presented. therefore they are fresh in STM at start of recall
• tulving (1985)

  argued that the MSM of memory was too simplistic - instead he suggested that there were different types of LTM:

  explicit memory - episodic and semantic memory

  implicit memory - procedural memory

  • difference between them is one is conscious or unconscious control.
• Episodic memory

  Long term memory store for personal events/memories. People, objects, places and behaviours involved
• Semantic memory

  Long term memory store for our knowledge of the world - meanings of words and concepts
• Procedural memory

  Store for our knowledge of how to do things - includes memories of learned skills
• Episodic

  Personal events

  Specific details of the events, context and emotion.

  Frontal lobe
• Semantic

  Knowledge eg, maths and language - recall a particular fact/ by meaning
• Procedural

  Automatic once learned

  Body recalls before the episodic and semantic

  Connected with skills

  Remembering how to do something

  Less aware of our memories
• Semantic and procedural similarities

  Memories like learning flags become automatic
• Episodic and procedural similarities

  Memories from episodic are impacted with procedural eg, first time riding a bike
• Episodic and semantic similarities

  Memories are "knowing that"

  Personal events

  Both rooted in episodic memory

  Conscious recall