Overview of Memory
• Atkinson-Shiffrin Model
Sensory Signals
Sensory Memory
Short-Term Memory
Long-Term Memory
ATTENTION
REHEARSAL
RETRIEVAL
“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 EG S A UT 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 BO D W AI 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
Probe Delay
# of letterspotentially recalled
500 ms0 ms never
0
4
10
Duration
• Partial Report
Delay
# of letters potentiallyrecalled
Interpretation:1. Information dwells in a brief storage “buffer”2. duration of storage lasts about 1/2 of one second
500 ms0 ms never
0
4
10
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