Overview of Memory
RETRIEVAL
• Atkinson-Shiffrin Model
ATTENTION
Sensory
Signals
Sensory
Memory
Short-Term
Memory
Long-Term
Memory
REHEARSAL
“Types” of Memory
• Sensory Memory
– brief ( < 1 second)
– preattentive / parallel processing (very
large capacity)
Sensory Memory
Capacity
• Describe a simple experiment that could
measure the capacity of “memory”
Capacity
• Describe a simple experiment that could
measure the capacity of “memory”
• Briefly present some letters or digits and
then ask the subject to report them
– Called “whole report”
Capacity
F S F E
G S A U
T O C G
Capacity
“Recall as many letters as you can”
Capacity
• George Sperling - Systematic investigation
of memory capacity
– Result: subjects accurately recall 3 or 4 items
– What can you conclude from this result?
Capacity
• What if subjects forget as they are
recalling?
Capacity
• What if subjects forget as they are
recalling?
• How could you modify the experiment to
measure the instantaneous capacity, before
any forgetting can occur?
Capacity
• Partial Report - briefly present letters or
digits and ask subject to report only some of
them
“Report the letters in the row
indicated by the arrow”
Capacity
U E S B
O D WA
I B V S
Capacity
Capacity
Which Letters?
Capacity
• Partial Report
• Result: subjects can recall any 3 or 4 letters
that are indicated by the arrow !
Capacity
• Partial Report
• Result: subjects can recall any 3 or 4 letters
that are indicated by the arrow !
• What does this mean about the capacity of
memory?
Capacity
• There is some part of the perception system
that stores huge amounts of information…
Duration
• But for how long? How would you design
an experiment to measure the duration of
this high-capacity memory system?
Duration
• But for how long? How would you design
an experiment to measure the duration of
this high-capacity memory system?
• Vary the onset of the probe
Duration
• Partial Report
# of letters
potentially
recalled
10
4
0
0 ms
500 ms
never
Probe Delay
Duration
• Partial Report
10
# of letters
potentially 4
recalled
0
0 ms
500 ms
Delay
never
Interpretation:
1. Information dwells in a brief storage “buffer”
2. duration of storage lasts about 1/2 of one second
Iconic Memory
• a brief storage of “raw data” in the visual
system
Echoic Memory
• Auditory information is stored in a similar
sensory “buffer”
– Echoic memory seems to last for several
seconds
Properties of Sensory Memory
1. Brief (iconic ~500ms; echoic ~2 seconds)
Properties of Sensory Memory
1. Brief (iconic ~500ms; echoic ~2 seconds)
2. unlimited capacity
Properties of Sensory Memory
1. Brief (iconic ~500ms; echoic ~2 seconds)
2. unlimited capacity
3. pre-attentive
Next Time:
• Short-term memory