L2 - Stage Theory of Memory

• Short-term memory


  Limited capacity (7 + 2 items), rapid forgetting, 15-20 sec
• Long-term memory


  Massive capacity, very slow (or no) forgetting
• The stage theory of memory
• Sensory memory


  • Lasts for 0.3 to 3 seconds
• Serial position effect


  Actual recall performance shows primacy and recency effects
• Differential manipulation of primacy and recency effects provides further evidence for the involvement of two memory systems
• Bias in encoding - phonetic (STM) vs semantic (LTM)
• Baddeley and Hitch working memory model


  Central executive, visuospatial sketchpad, phonological loop, episodic buffer
• Chunking


  Grouping individual items into larger (and usually more familiar) units of meaning to get around the limited capacity of working memory
• Maintenance rehearsal


  Rehearsal crucial for transfer of information into LTM
• More than maintenance rehearsal required for effective transfer to LTM
• Patients H.M. and K.F. provide evidence for the existence of separate memory systems
• Atkinson and Shiffrin's multi-store model of memory
• George Sperling's research on sensory memory
• Miller's (1956) "magic number" 7 + 2 for short-term memory capacity
• Baddeley and Hitch's working memory model challenges the simplicity of the previous short-term memory model
• Craik and Watkins' (1973) research on maintenance rehearsal
• Lots of studies suggests that there are multiple components to memory and systems
• Patient H.M


  Most important in study of memory (1926-2008)
• Henry was riding bicycle fell off and was concussed
• The impact damaged his brain and he started having epileptic seizure getting worse as he aged
• By the time he was in his late teens the seizures had a severe impact on his life
• In the age of 27 in 2953 it was decided the only way to help him was remove part of brain which was causing the issue
• Henry's condition after surgery


  • Seizures were better controlled
  • Could no longer form new memories
  • Living in the present with memory only for events of the last 20 seconds
  • Described it as living in a dream where everything in the past made no sense
• The impact reduced impacted the front of brain and the neurons starting firing abnormally and impacting cells around them and impacted sensation and perception
• The seizures came from his temporal lobes on each sides of his brain
• Henry served as a participant in many studies of memory
• The surgeon removed henry entire medial lobe
• Suzanne Corakan regularly visited Henry and he never knew who she was
• Henry's short-term memory

  Intact, he understood information of words and language, and his intelligence actually improved
• K.F's short term memory was impacted in a test testing STM
• What was lost for Henry


  Ability to remember what happened 20 seconds ago due to impaired long-term memory
• Test of short term memory

  1. Repetition of numbers

  2. Repetition of letters

  3. Repetition of word strings of increasing lengths
• Henry lost his hippocampus and perirhinal cortex
• Evidence for existence of separate memory systems


  • Neurophysiological evidence shows medial temporal lobe damage produces dense anterograde amnesia (LTM) with intact chunking
• 7 + - 2 is a healthy individual (Miller 1956)
• The same effect can occur reversed with an intact LTM but a damaged STM
• Short term memory

  Lasts for around 15-20s
• There is also a question whether there is storage or information prior to STM. This is called sensory memory. This was tested by a array of letter by George Spieling, they were presented briefly and then played a high, medium or low note.

   

  If you were to even delay the tone outside of 300 milliseconds, you don’t get the effect due to sensory memory. It shows that if you are presented you will store the information for a brief period of time.
• Study by Warrington and Shallice in 1969


  • Presented patient K.F who was 28 years old and had a motorcycle accident which resulted in a hematoma which meant the left partial subdural hematoma was removed