Transcript Short Term Memory and Encoding

Memory and encoding
Memory as Information Processing
– similar to a computer
• write to file
• save to disk
• read from disk
• Encoding
– the processing of information into the
memory system
Storage and retrieval
• Storage
– the retention of encoded information
over time
• Retrieval
– process of getting information out of
memory
Memory
 Sensory Memory
 the immediate, initial recording of
sensory information in the memory
system
 If you can recall information, it must first be
stored!
 According to Atkinson and Shiffrin’ 3-step
model, the first stop is sensory memory or the
sensory registers.
Sperling’s experiment
Sperling’s partial report technique illustrates the
limitation of sensory memory.
When subjects were told to report ALL 9 letters flashed
for a fraction of a second, they could not, but when
subjects instructed to report 3 of the letters (one row of
3 letter row display of 9 total letters) they could do so
with few errors
This proved that sensory memory could hold the
information, but only very briefly
Storage: Sensory Memory
 Sensory memory holds information just long enough
to recognize and transfer it to STM for further
processing
 This happens through selective attention
Selective attention allows only a small percentage of
sensory messages that bombard us to enter
conscious awareness.
It is controlled not only by the focus of our attention
but also the expectancies we have prior to exposure
Storage:
Sensory Memory
 Iconic Memory
 a momentary sensory memory of visual
stimuli
 a photographic or picture image memory
lasting no more that a few tenths of a
second
 Tests of George Sperling
 Echoic Memory
 momentary (3-4 sec) sensory memory of
auditory stimuli
Short term and Long term
memory
• Short Term Memory/Working Memory
– activated memory that holds a few items
briefly
– look up a phone number, then quickly dial
before the information is forgotten
• Long Term Memory
– the relatively permanent and limitless
storehouse of the memory system
A Simplified Memory
Model
Sensory input
Attention to important
or novel information
Encoding
External
events
Sensory
memory
Short-term
memory
Encoding
Long-term
memory
Retrieving
Automatic Processing
We process an enormous amount of information
effortlessly, such as the following:
1. Space: While reading a textbook, you
automatically encode the place of a picture on
a page.
2. Time: We unintentionally note the events that
took place during the day.
3. Frequency: You effortlessly keep track of
things that happen to you.
DEMO
 DO NOT write down the following list. Listen and
read them, then try to recall them when prompted:
CLINTON
RUJ
FET
TEXTBOOK
NAV
BUSH
FULFILL
GEF
MANDATE
FET
47
TAL
Effortful Processing
 While some information is automatically and
effortlessly processed, some requires focus and
attention
 Attention is defined as selection certain information for
further processing
We normally pay attention to only a small portion of
incoming information
We pay attention to things according to…
Meaningfulness
Distinctiveness
Repetition
 Broadbent’s Cocktail Party Phenomenon: we tune
out other sounds to focus on what is important
Ebbinghaus and Rehearsal
Effortful learning usually requires rehearsal or
conscious repetition
Ebbinghaus studied rehearsal by using nonsense
syllables:
TUV YOF GEK XOZ
The more times practiced on Day 1, the fewer
repetitions to relearn on Day 2
Spacing Effect
 distributed practice yields better long- term
retention than massed practice
Memory:
Ebbinghaus’ Contributions
The more the syllables
were rehearsed
(practiced) on the first
day of learning, the
fewer rehearsals it took
to relearn them on the
second.
Encoding: Serial Position
Effect
Percent
age of
words
recalled
90
80
Serial Position
Effect--tendency
to recall best
the last items in
a list, and then
the items at
beginning
70
60
50
40
30
20
10
0
1
2
3
4 5 6 7 8
Position of
word in list
9
10 11 12
The Serial Position Effect:
Benefits of Rehearsal + Working Memory
When we are given a list of
things to remember, we often
remember the first items and
last items on the list.
This is called the serial
position effect.
We are able to rehearse those
at the beginning the most and
those at the end are still in our
working memory!
Primacy Effect: tendency to
recall the first items on the list
Recency Effect: tendency to
recall the last items on the list
Making Memories Last…
 Information quickly learned is
information quickly lost!
 Spacing Effect: distributed
study time yields better longterm retention than massed
practice (cramming)!
 Testing Effect: more
frequent quizzing or
previously studied material
yields better long-term
retention
 Bottom line: spread your
studying out over time and
quiz yourself frequently!
This is sooooo
much fun! I
will do it
every night
until the test!
Unless evil
clowns stop
you!
Chunking
Organizing items into a familiar,
manageable unit. Try to remember the
numbers below.

1776149218121941
Chunking
If you are well versed with American
History, chunk the numbers together and
see if you can recall them better.
1776 1492 1812 1941
What Do We Encode?
 Semantic Encoding
 encoding of meaning
 including meaning of words
 Acoustic Encoding
 encoding of sound
 especially sound of words
 Visual Encoding
 encoding of picture images
What We Encode:
Levels of Processing
 Which type of encoding – visual,
acoustic or semantic – helps us
to remember best?
 Craik and Tulving (1975)
 Subjects forced to encode
words in the three ways
 Visually (is it capitalized?)
 Acoustically (does it rhyme
with…)
 semantically (Would it fit into
the sentence?)
 Found that semantic encoding
yielded best recall!
 Spend TIME learning and make
MEANING out of what you wish
to recall!
 Self-Reference Effect: meaning
that is personal – relate
information to ourselves.
Bransford and Johnson (1972) had subjects read the following paragraph:
The procedure is actually quite simple. First you arrange things into different groups
depending on their makeup. Of course, one pile may be sufficient depending on how
much there is to do. If you have to go somewhere else due to lack of facilities that is the
next step, otherwise you are pretty well set. It is important not to overdo any particular
endeavor. That is, it is better to do too few things at once than too many. In the short run
this may not seem important, but complications from doing too many can easily arise. A
mistake can be expensive as well. The manipulation of the appropriate mechanisms
should be self-explanatory, and we need not dwell on it here. At first the whole procedure
will seem complicated. Soon, however, it will become just another facet of life. It is
difficult to foresee any end to the necessity for this task in the immediate future, but then
one never can tell.
Without the context of “doing laundry, subjects could not recall much!
Storage:
Short-Term Memory
Percentage
90
who recalled
consonants 80
70
60
50
40
30
20
10
0
 Short-Term
Memory
3
6
9
12
15
18
Time in seconds between presentation
of contestants and recall request
(no rehearsal allowed)
 limited in
duration and
capacity
 “magical”
number 7+/-2
(Miller, 1956)
Storage: Short Term Memory
Unless information in STM is
important/meaningful or is actively
rehearsed, it quickly vanishes from STM and
is displaced by whatever comes into our
minds next
Displacement occurs, then, when new
information enters STM and pushes old out
STM storage capacity is limited: the average
adult can hold about 5-9 bits or chunks of
information in STM
George Miller (1956) Magical Number
Short Term Memory
Capacity
STM (working memory) is what is in your
mind RIGHT NOW.
Information in STM only remains there for
about 20-30 seconds
STM is very sensitive to interruption and
interference
Memory Span
 Memory span is a measurement of STM capacity
It measures the largest number of items that can be recalled
perfectly from STM after only one presentation
No study/rehearsal time is allowed
Sometimes used as a component of IQ tests
 In STM, acoustic coding seems to dominate –
especially for verbal information
 Information in STM may be new or retrieved from LTM
to be thought about and used.