Type of memory

• Memory is a process in which information is retained about the past
• Three types of memory are

  Sensory register

  Short term memory

  Long term memory
• Stages of sensory register

  • Temporarily stores information from our senses
  • Unless attention is paid, the information disappears quickly through spontaneous decay
  • Limited capacity and limited duration
  • Information coded by sense that has picked it up
• Stages of short term memory

  • Limited capacity and limited duration
  • Coding usually acoustic
• Stages of long term memory

  • Unlimited capacity that is theoretically permanent
  • Coding is semantic
• Types of long term memory

  • Episodic
  • Semantic
  • Procedural
• Episodic memory is:

  Information about events.

  Information about places visited and emotions felt.

  Declarative memory --> consciously recalled
• Semantic memory is:

  Facts and knowledge learned through conscious recall
• Procedural memory is:

  Stores knowledge of how to do things

  i.e. walking and swimming

  Cannot consciously recall memory
• Sperling investigated sensory registers using very brief displays
• Sperling (1960) Sensory register - Method

  • Lab experiment
  • Grid of 3 row of 4 letters for 50ms
  • Immediately recall whole grid or randomly chosen row indicated by a tone
• Sperling (1960) Sensory register - Results

  Recall whole grid only managed to recall 4 or 5 letters

  Recall row managed average of 3 letters regardless of the row
• Sperling (1960) Sensory register - Conclusion

  Ps didn't know which row selected, Ps would have been able to recall three items from any row.

  Almost whole grid held in sensory register

  Couldn't report whole grid as trace faded before finished recall
• Sperling (1960) Sensory register - AO3

  Lab experiment = highly scientific

  Variables controlled = good replicability

  Artificial setting = lack ecological validity

  People don't usually have to recall letters by a sound so it doesn't reflect real world encounters
• Peterson and peterson (1959) investigated STM using trigrams
• Peterson and peterson (1959) Duration of STM - Method

  • Shown nonsense trigrams
  • Recall after 3, 6, 9, 12, 15, 18 seconds
  • During paused asked to count backwards in 3s
  • Used interference task
• Peterson and peterson (1959) Duration of STM - Findings

  • After 3 seconds Ps recalled trigram 80% correct
  • After 18 seconds Ps recalled trigram 10% correct
• Peterson and peterson (1959) Duration of STM - Conclusion

  When rehearsal is prevented, little info can stay in STM longer than 18 seconds
• Peterson and peterson (1959) Duration of STM - Evaluation

  • Lab experiment = results are reliable
  • Controlled variables = Good replicability
  • Artificial setting and task = lack ecological validity
  • One stimulus used, duration could depend on stimulus used
  • Each P saw different trigram --> confusion
• Bahrick et al (1975) investigated long term memory in a natural setting
• Bahrick et al (1975) long term memory - Method

  • 392 asked to list names of ex-classmates
  • Shown photos and asked to recall names or given names and asked to match them to a photo
• Bahrick et al (1975) long term memory - Findings

  • In 15years after leaving school Ps recognise 90% names and faces
  • 60% accurate of free recall
  • After 30 years free recall 30% accurate
  • 48 years name recognition 80% accurate photo 40% accurate
• Bahrick et al (1975) long term memory - Conclusion

  • Recognition is better than recall
  • Huge store of information but not easy to access
• Bahrick et al (1975) long term memory - Evaluation

  • Field experiment = high ecological validity
  • Hard to control variables = findings less reliable
  • Don't know why info was recalled well
  • Better recall on LTM than other studies --> recall was more meaningful
  • Results can't be generalised to other info stored in LTM
• Jacobs (1887) STM and LTM have different capacities
• Jacobs (1887) Capacity of STM - Method

  Ps presented string of letters or digits

  Repeat them back in same order

  Digits or letters increased until fail to recall
• Jacobs (1887) Capacity of STM - Findings

  • Recalled 9 digits
  • Recalled 7 letters
  • Capacity increased with age during childhood
• Jacobs (1887) Capacity of STM - Conclusion

  STM has limited storage capacity 5-9 items

  STM increase with age --> memory techniques

  Digits easier than letter
• Jacobs (1887) Capacity of STM - Evaluation

  Artificial setting = lack ecological validity

  Meaningful info can be recalled better

  Previous sequence recalled by Ps may have been confused by previous trials
• Miller review research of STM capacity

  • People can remember about 7 items
  • Capacity of STM is 7+-2
  • Chunking used to combine letters and numbers into larger units
• Baddley (1966) coding in STM and LTM - Method

  • 4 sets of words acoustically similar/dissimilar or semantically similar/dissimilar
  • Used independent groups
  • Recall words immediately or after 20 min task
• Baddley (1966) coding in STM and LTM - Findings

  Ps had problem recalling acousitically similar words immediately

  Ps had problem recalling semantically similar words for LTM
• Baddley (1966) coding in STM and LTM - Conclusion

  • Patterns of confusion between similar words suggest LTM is more likely to rely on semantic coding and STM on acoustic coding
• Baddley (1966) coding in STM and LTM - Evaluation

  Lacks ecological validity - artificial task

  Other types of LTM exist and other methods of coding

  Independent group design no control over participant variables