PSC 1 Lecture Notes - Lecture 9: Long-Term Memory, Sensory Memory, Sketchpad
PSC1 Lecture 9 – Memory
• Memory is fallible (does not work like a video camera)
o People are selective in what they remember
o People can become convinced that something happened even when it did not
actually happen
• 3-stage model of memory formation
o Model not completely accurate in the details and not used today
o Composed of three components: sensory memory, short term memory, and
long-term memory
▪ Sensory memory: captures incoming information from the environment
and holds it for an extremely short period of time
▪ Short term memory: requires attention encoding to hold memories for a
slightly longer period of time
• Rehearsal of information means memories remain active and can
be held for longer period of time
• No rehearsal results in the memory being discarded
▪ Long term memory: requires multiple cycles of rehearsal that would
transfer and store the memory from short term memory to long term
memory
• Memories can be retrieved into short term memory from long
term memory to reactivate it
• Sensory memory
o Iconic (visual) and echoic (auditory) information
o Duration: about half a second
o Capacity: cannot exactly determine because memories disappear before they
can even be repeated
▪ Experiment: flash series of letters for about 50ms and subjects must
repeat the letters back
• Subjects can usually get through half of the letters before their
memory decays
▪ No-tone and tone conditions
• No-tone conditions had 50% accuracy (subjects got through half
the letters)
• Tone conditions: tone indicated which row of letters to start on
o 100% accuracy on indicated row that correlated with the
tone
• Short-term memory
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o Duration: about 30 seconds without rehearsal
o Capacity: 7 (plus or minus 2) chunks
▪ Practice or rehearsal of the material causes accuracy to remain high
o Primacy and recency effects
▪ Things at the beginning (primacy) and things at the end (recency) are
remembered better than things in the middle
▪ Primacy effect occurs within long term memory while recency effect
occurs within short term memory
o Working memory model
▪ Modern replacement of short term memory of the 3-stage model
• Characterized as an active rather than a passive system
• Central executive: decision-making system
o Decides which information or memories are needed for
specific task
▪ Information from external environment or from
long term memory
o Controls phonological loop and visuo-spatial sketchpad
• Phonological loop
o Phonological store and articulatory process for auditory
information to remain active
o Equal to rehearsal in 3-stage model
• Visuo-spatial sketchpad for allowing visual information to remain
active
• Long-term memory
o Duration: lifetime
o Capacity: unknown, unlimited
• Problems associated with the 3-stage model
o Time in short term memory does not equal storage in long term memory
▪ Short term memory more active than passive
▪ Time in rehearsal does not determine storage
• Cannot be used to make accurate predictions about memory
formation
o Not sophisticated enough to explain all aspects of human memory such as use of
different memory systems for processing different types of knowledge
▪ Model states that all types of knowledge are processed by the same
memory system (inaccurate)
• Different types of knowledge
o Episodic (events experienced) vs semantic (meaning of things)
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