The modal model because of the huge influence it has had on memory research.
Dec 30, 2015
The modal model because of the huge influence it has had on memory research.
Structure Sensory Short-term Long-term
Processes Encoding: activities taking place during presentation
of information (study phase) Storage: activities taking place during the study-test
interval Retrieval: activities taking place when stored
information is utilized (test phase)▪ Failure to retrieve – forgetting
Purpose
Passively registers input & briefly retains stimulus trace after stimulus vanishes
Functions Helps us retain info that doesn’t last long Aids perception by allowing you to continue
processing after the stimulus is gone Keeps accurate record of stimulation so most
important can be processed further
DURATION < 30 sec lifetime
CAPACITY ~7 chunks unlimited
MAIN CODE acoustic- semantic
articulatory
RETRIEVAL serial parallel
FORGETTING decay, interferencedisplacement
STM LTM
Memory span the number of items that can be correctly
recalled in order (e.g., digit span test).
Miller (1956)“The Magical Number Seven, Plus or Minus
Two” Limit of 7 + 2 chunks in STM Chunk: unit of info organized according to a
rule or some familiar pattern Chunk: collection of elements that are
strongly associated.
B V S M T A U I vs. T V U S A I B M
1 4 9 2 1 7 7 6 1 9 4 5 1 9 6 3 . . . F B I J F K F D R L B J
Task: immediate serial recall (“memory span”)
• Capacity of STM: "about seven chunks”
0
20
40
60
80
100
Serial Position
Nu
mb
er o
f Peo
ple
Wh
o
Rec
alle
d
Support for A & S model Two serial position effects
Primacy Effect Better recall for words at beginning of list Recalled from LTM
Recency Effect Better recall for words at end of list Recalled from STM
Support for A & S modelEffect on serial position curve
Speeding up presentation rate? Eliminate primacy effect
Delaying the start of recall with an interfering task? Eliminate recency effect
Task: free recall of word lists
Primacy effect: better recall of first few wordsRecency effect: better recall of last few words
Glanzer & Cunitz (1966): delay between study and test eliminates recency effect:
0.2
0.4
0.6
0.8
Pro
po
rtio
n C
orre
ct
1 3 5 7 9 11 13 15
Serial Position
No Distractor
30 Seconds
One Syllable Five Syllables
Sloth HippopotamusMumps TuberculosisSchool UniversityGreece YugoslaviaSwitch RefrigeratorMath PhysiologyMaine LouisianaScroll PeriodicalZinc Aluminum
• Which list is faster to read aloud?
• Which list is harder to recall?
STM CAPACITY AND REHEARSAL TIME
0.4
0.6
0.8
1
Pro
po
rtio
n C
orre
ct
1 2 3 4 5
Number of Syllabes
Number of syllabes Reading Rate 1 mumps 2.2 words/sec 2 measles 2.0 “ 3 leprosy 1.7 “ 4 diphteria 1.5 “ 5 tuberculosis 1.3 “
Task: immediate serial recall of 6-item lists
The word length effect
% words in correctTYPE OF SERIAL positionRECALL TASK:
A S CSTM: 5 words,one trial, no delay __% __% 76%
LTM: 10 words,four trials, delay __% __% 72%
Acoustically similar lists: mad, plan, nap, bag….Semantically similar lists: big, large, huge, great…Control lists: pen, day, wish, bill….
.09
.70
.64
.53
Varied set of digits held in STM E.g., memory set size of four: 2, 5, 8, 1
Task: is it in the set?2 yes7 no
400
450
500
550
600
650
RT
(m
se
c)
1 2 3 4 5 6
Size of Memory Set
YES
NO
Retrieval for STM: parallel or serial?
Conclusions:
STM duration: most info was gone
after about 18 seconds.
Why do we forget? Strong support for
decay? Retention Interval
0 2 4 6 8 10 12 14 16 18 20
Per
cen
tage
Re
call
0
20
40
60
80
100
3 Words
3 Letters
Lachman, Lachman, & Butterfield (1979)
Replicated the Peterson & Peterson Task.
But, they also analyzed their data by trial number.
1st trial is 1st word presented to participants
Conclusion: Forgetting almost does not
occur at the first trial, But more forgetting with
each succeeding trial. Why?
Trial Number
1 2 3 4 5 6
Per
cent
age
Rec
all
0
20
40
60
80
100
3 SecondDelay
18 SecondDelay
Adapted from Keppel & Underwood (1962)
•Things learned prior to study can proactively interfere with memory STUDY phase.
• Things learned between study and test can retroactively interfere with memory TEST phase.
0
0.2
0.4
0.6
0.8
1
Re
ca
ll P
ro
ba
bility
3 6 9 12 15 18
Recall Delay (sec)
all trials
first trial
Proactive Interference (PI) also occurs.
Proactive interference refers to forgetting that occurs due to prior learning.
Current statusSensory memory is part of
perception, rather than memoryShort-term memory is more flexible
than just a passive storehouse working memory
Parallel processing