Encoding - when information comes
into our memory system (from
sensory input) it need to be changed
into a form that the system can cope
with, so that it can be stored.
Information in STM tends to be
encoded acoustically, where as LTM
information tends to be encoded
semantically.
Acoustic encoding involves encoding information
according to how it sounds.
Semantic encoding involves
coding information
according to its meaning.
Capacity - this is a measure
of how much we can hold in
our memory. STM is very
limited in capacity, while
LTM has potentially
unlimited capacity.
Duration - STM has very
limited, whereas LTM has
potentially unlimited
duration.
Storage - once encoded, we need to store the
memory trace somewhere within the memory
system.
Retrieval - Storing a memory
isn't enough - we also need
to be able to recall and
remember it.
Types of memory
Long term memory (LTM)
Short term memory (STM)
Baddeley 1966
Encoding in the STM
and LTM
Aim
Baddeley's starting point
was the knowledge that
people tend to make
acoustic errors when using
STM. (Conrad 1964)
He aimed to gather further and additional information whether
LTM was affected by acoustic confusitions. He wanted to see if
the memory store was affected by semantic confusions - words
that meant the same thing.
Experiment testing encoding in STM and LTM
STM -75 young servicemen were divided into 4 groups. each group heard one
word list. this list was repeated 4 times. after each trial participants were
shown a list of all words jumbled up and asked to recall them in the correct
order. this was done because it was the only way to ensure that acoustic
confusions were detected. participants just had to get the right order.
LTM - 72 participants were divided into 4
groups ad shown one of the lists. this time
recall was not immediate. there was a 20
minute retention interval during which the
participants performed another task. then
they were asked to recall the list as before.
this was repeated 4 times.
Findings
In all experiments participants remembered more
words on each successful trial, though this levelled off
after 4.
Conclusions
Experiment 1 shows that words in STM
tend to be remembered in terms of their
sounds (acoustically). This is indicated by
the difficulty participants had when the
words sounded the same.
Experiment 2 shows that words in LTM
tend to be coded in terms of their meaning
(semantically). this is indicated by the
difficulty participants had when the words
meant similar things.
Encoding AGE - an age deficit in encoding suggests that older
people encode words and other events in a way that is
different from encoding be younger people, although evidence
for this is rather mixed. there is some evidence to indicate that
younger people use more precise elaborations when presented
with simple sentences, while older people benefit more from
elaborations provided by others.
Criticisms
STM may not always use an acoustic code. Relys on
acoustic code for storing information, but some
experiments some that visual codes are also used in
STM.
There is more than one kind of
LTM. The experiments only use
one type of memory we
actually have lots of different
kind of memory.
The muti-store model of memory was
discovered by Atkinson and Shiffen. it starts
at the sensory memory where information
passes though into the STM, information can
be retrieved though external stimulus. the
STM can store 7 +/- 2 items and will only last
for 3 - 30 seconds. it is remembered in the
form of acoustic coding. (sound)
By rehearsal information can be
transferred from STM to LTM. The LTM is
unlimited but some information can be
forgotten by decay and the interference
of new information which can also cause
confusion.
Glanzer and Cunitz
Aim - to see if they could find
evidence for the existence of
separate STM and LTM memory
stores.
Procedure - participants were presented with
a list of words, on at a time, and then asked to
recall the words in any order. participants were
divided into 2 groups: immediate recall group
and Delayed recall group.
Findings - participants in immediate
group remembered the first and last
words best, while participants in delayed
group remembered words at beginning of
the list. Neither group recalled words in
the middle of the list.
Conclusion - Both groups remembered the words
from the start because they were stored in the
LTM. Words at the end were stored in the STM.
When recall was delayed by a distractor task it
prevented maintenance rehearsal and therefor
affected the regency effect without changing the
primary effect.
Atkinson and Shiffin (1968) suggests memory is a flow of information though a system. There
are 3 distinct stages of the system: Sensory, Short term and Long term memory. Information
passes though each stage in a liner fashion. Information from External senses enter the sensory
memory in an uncoded way for brief periods of time so can be passed into short term memory.
CASE STUDIES (HM AND CLIVE WEARING)
HM - Scoville and Millner, 1957 studied a man referred to as
HM. they had there Hippocampus removed to help with his
epilepsy. But could not form new long term memory, this
suggests that hippocampus may function as a 'gateway' though
which new memories must pass before entering into
permanent storage.
CLIVE WEARING - Clive's condition is where he can't transfer information from STM
into LTM. Both of his hippocampus' are damaged. he suffered from viral stipulates. His
LTM didn't work anymore as he can't remember any old or new memories. E.g. his
wifes name and his wedding day. He got angry with himself that he couldn't
remember.
Working memory model
The Working Memory Model (Baddeley and Hitch, 1974) Working
memory is short-term memory. Instead of all information going into
one single store, there are different systems for different types of
information. Working memory consists of a central executive which
controls and coordinates the operation of two subsystems: the
phonological loop and the visuo-spatial sketch pad.
Central Executive: Drives the whole system
(e.g. the boss of working memory) and
allocates data to the subsystems (VSS & PL).
It also deals with cognitive tasks such as
mental arithmetic and problem solving.
Visuo-Spatial Sketchpad (inner eye): Stores
and processes information in a visual or
spatial form. The VSS is used for navigation.
The phonological loop is the part of
working memory that deals with spoken
and written material. It can be used to
remember a phone number. It consists of
two parts o Phonological Store (inner ear)
– Linked to speech perception Holds
information in speech-based form (i.e.
spoken words) for 1-2 seconds. o
Articulatory control process (inner voice) –
Linked to speech production. Used to
rehearse and store verbal information
from the phonological store.
Strategies for memory improvement
The method of Loci - the method of loci is to
remember something E.g. working memory
model you image a journey though a familiar
landscape or location such as a house where
you live.
Verbal Mnemonic - a variety of
memory improvement techniques
focus on words. E.g. an acronym, an
acrostic poem.
Visual imagery Mnemonic - visual imagery mnemonic systems take advantage of
this fact to create systems that allow you to commit virtually unlimited amounts of
information to memory. using imagery can make learning more fun and
interesting. Visual mnemonic techniques generally involve two tasks: 1.forming
mental images 2. making associations between images.
Mind mapping - splitting up information into
smaller sections can help us retain the
information more easily than large chucks of
reading.
Rehearsal - rehearsal is a term used by memory
researchers to refer to mental techniques for
helping us remember information.
Jacobs, 1887 (Capacity)
Aims - to demonstrate how much information could be stored in STM.
He develop the technique that was to isolate the one behaviour he was
interested in, he called it serial digit span.
Procedures - the digit span technique was to access the capacity of the
participants' memory. He used both letters (omitting W) and digits
(omitting & because it had 2 syllables). Reading of items was paced
using a metronome so that the experimenter said a sound every 1/2
second.
Findings - Jacobs found that participants could recall
more digits that letters. The average span for digits was
9.3 items, whereas letters were 7.3.
Conclusions - showed that STM has
a limited capacity of somewhere
between 5 and 9 items depending on
material used and age. Jacobs
suggests that it maybe because
there were only 9 digits and 25
letters. it might be due to a gradual
increase in brain capacity or it
maybe that people develop
strategies to improve their digit
span as they get older, such as
chunking.
Chunking
information that is
grouped into sections
so it is easier to
remember.
AGE - apper to be significant
age differences, as children get
older, their memory span also
increases from 2 at age 2, 4 at
age 5, 6 at age 9 and then 7 as
an adult.
Bahrick et al. (1975 )Study into the
duration of Long Term Memory
Their aim was to investigate the duration of very long term memory (VLTM),
he wanted to show memory could last over several decades or even a life
time. Also to see if VLTM is better than found in l laboratory studies.
Procedures •Nearly 400 participants
aged 17 to 74 where given various
tests such as •Ø A free – recall test.
They were asked to name all the
people in their graduating class. •Ø A
photo recognition test. The
participants were shown 50 photos
that were a mixture of photos from
the person’s high school year book
while others weren’t. •Ø A name
recognition test of ex-school friends
Along with a photo matching test and
a name matching test.
Findings •Test subjects who were tested with in
fifteen years of graduation where 90% accurate
with identifying names and faces (visual and verbal
recognition). •After forty-eight years it declined to
around 80% for name recognition and 70% for
photo recognition. •Free recall test results – after
fifteen years this was around 60% accurate, that
dropped to 30% after 48 years.
Conclusion Evidence shows that very long term memory works up to 57 years after graduation, but
there is a loss of memory over time. People remember visual recall (photos) better than verbal recall
(names). This suggests that in real life our memories contain a large amount of information, but we
are not always able to recall it. When given a recognition test this jogs our memory and we can
remember it (VLTM). Therefore our vast store of memory is there but not always easily accessed.
Peterson and Peterson
Aim - To investigate the duration of short-term
memory, and provide empirical evidence for the
multi-store model.
Procedure - A lab experiment was conducted in which 24 participants (psychology
students) had to recall trigrams (meaningless three-consonant syllables, e.g. TGH). To prevent
rehearsal participants were asked to count backwards in threes or fours from a specified random
number until they saw a red light appear. This is known as the brown Peterson technique.
Participants were asked to recall trigrams after intervals of 3, 6, 9, 12, 15 or 18 seconds.
Findings - The longer the interval delay the less trigrams were recalled. Participants were able to
recall 80% of trigrams after a 3 seconds delay. However, after 18 seconds less than 10% of trigrams
were recalled correctly.
Conclusion - Short-term memory has a limited duration when rehearsal is prevented. It is
thought that this information is lost from short-term memory from trace decay. The results of the
study also show the short-term memory is different from long-term memory in terms of duration.
Thus supporting the multi-store model of memory.-
Criticisms: This experiment has low ecological
validity as people do not try to recall trigrams in
real life.