Memory

• Henry Molaison - Patient H.M.


  Suffered a concussion which damaged part of his brain at an early age, triggering epileptic seizures years later. The damage caused inhibition in certain parts of the brain, with neurons firing abnormally.
• At the age of 27 H.M. had his medial temporal lobe removed on both sides of his brain


  Resulting in far fewer seizures (the damaged part of the brain had been removed) but he could not maintain memories. Anything longer than 15-20 seconds (STM) he couldn't remember.
• H.M.

  • His short term memory is intact and his intelligence was improved after the surgery. Able short term memory and impaired long term memory.
• Patient K.F.


  28 years old motorcycle accident, damage to parietal subdural haematoma. Had long term memory but impaired short term memory.
• Short term memory system


  • Holds information for 18-20 seconds
  • Limited capacity (magic number -7+2)
  • Rapid forgetting
  • Poor recall for words that sound the same
  • Not a unitary model, can process larger numbers of items if the information is presented in different modalities, aka both can be stored at the same time (visual and auditory can exist in STM at the same time and do not implicate one another)
  • A mental workbench rather than a storage platform
  • Maintenance rehearsal works to store items in STM
• Long term memory system


  • Has massive capacity: over decades
  • Very slow or no forgetting
  • Takes more than just maintenance rehearsal (repeating over and over) to encode memory's
  • Just near exposure isn't enough
• Subjects were asked to remember a sequence of letters that exceeded the magic number


  • The primacy affect- LTM affect, remembered items at the start of the list, nothing interfering with them.
  • The recency affect- STM affect, items at the end of the list, have just been told them can sit for 20s
• Preventing rehearsal stops the recency affect and STM from occuring.
• Phonetic STM

  Poor recall for words that sounds the same
• Semantic LTM


  Poor recall for words that mean the same
• Baddeley and Hitch (1974)


  • Suggested that visual and auditory information STM are separate
  • STM as a mental workbench rather than a storage platform
• Chunking (grouping individual items) can help to get around the limited capacity of working memory
• Just near exposure is not enough to get into STM
• Maintenance rehearsal


  Repeating over and over to hold in STM but won't get into LTM
• PTSD

  psychophysiological reactivity in response to trauma related stimuli
• what causes PTSD

  memories are enhanced due to arousal, attention and high emotions
• misattribution

  source monitoring error, attributing memory to the wrong source.