Module 25

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Module 25

• Storage Retaining Information

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Sensory Memory

• Atkinson-Shiffren model sensory
  memory-short-term memory - long-term memory
• We have a brief photographic memory, ie iconic
  memory, that lasts a few tenths of a second (see
  Sperling, p. 353).
• We also have a brief auditory memory called
  echoic memory.

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Short-Term Memory

• Limited in duration. Unless meaningfully encoded
  or rehearsed, disappears quickly.
• Short-term memories are rarely present after
  about 12 seconds.
• STM capacity is limited 7 2.

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Long-Term Memory

• LTM has a limitless capacity.
• The average adult has about a billion bits of
  info. in LTM.

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Storing Memories in the Brain

• Lashley (1950) trained rats to solve a maze then
  cut out pieces of the cortex.
• The rats retained at least part of the memories
  to solve the maze. Memories are not in a single
  specific spot.
• Theyve also wondered if memories are rooted in
  the brains electrical activity.
• Yet memories in hamsters survive a brain
  blackout.

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Synaptic Changes

• Kandel and Schwartz studied neural changes in
  Aplysia when conditioned with electric shock.
• When learning occurs, they found that Aplysia
  releases more serotonin at certain synapses.
• Other studies showed that learning causes
  increased sensitivity in neurons. Less prompting
  is now needed to release a neurons
  neurotransmitter this is long-term potentiation
  (LTP).
• Drugs that block LTP interfere with learning.

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Stress Hormones and Memory

• Hormones released when stressed or excited boost
  learning and retention.
• This is why we remember exciting or shocking
  events for so long.
• Prolonged stress however, corrodes neural
  connections and disrupts memory.

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Storing Implicit and Explicit Memories

• Some amnesic patients remember the past but can
  not form memories for new facts and things they
  have done.
• However they can be classically conditioned and
  can learn new skills without awareness they have
  learned them.
• We may have two types of memories
• 1) Implicit Memory (procedural memory) consists
  of motor and cognitive skills, and classical and
  operant conditioning.

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• 2) Explicit Memory (declarative memory) consists
  of semantic memory (facts and general knowledge)
  and episodic memory (personally experienced
  events).
• The hippocampus appears to be important in the
  laying down of explicit memories (see page 359).
  Frontal lobe is also important.
• The cerebellum may be important for implicit
  memories.