1. Study of Memory in Psychology
Dr. Magda Fahmy
Professor of Psychiatry
Suez Canal University
megofahmy@yahoo.com

2. • “Memory is the process of maintaining
information over time.” (Matlin, 2005)
• “Memory is the means by which we draw on
our past experiences in order to use this
information in the present.’ (Sternberg, 1999)

3. • Memory is the term given to the structures
and processes involved in the storage and
subsequent retrieval of information.
• Memory is involved in processing vast
amounts of information. This information
takes many different forms, e.g. images,
sounds or meaning.

5. 1. Encoding and Memory
• When information comes into our memory
system (from sensory input), it needs to be
changed into a form that the system can cope
with, so that it can be stored. (Think of this as
similar to changing your money into a different
currency when you travel from one country to
another).
• For example, a word which is seen (on the
whiteboard) may be stored if it is changed
(encoded) into a sound or a meaning (i.e.
semantic processing).

6. 1. Encoding and Memory
• There are three main ways in which
information can be encoded (changed):
• 1. Visual (picture)
• 2. Acoustic (sound)
• 3. Semantic (meaning)

7. 1. Encoding and Memory
• For example, how do you remember a
telephone number you have looked up in the
phone book? If you can see it then you are
using visual coding, but if you are repeating it
to yourself you are using acoustic coding (by
sound).

8. 1. Encoding and Memory
• Evidence suggests that this is the principle coding
system in short term memory (STM) is acoustic
coding.
• When a person is presented with a list of
numbers and letters, they will try to hold them in
STM by rehearsing them (verbally).
• Rehearsal is a verbal process regardless of
whether the list of items is presented acoustically
(someone reads them out), or visually (on a sheet
of paper).

9. 1. Encoding and Memory
• The principle encoding system in long term
memory (LTM) appears to be semantic coding
(by meaning). However, information in LTM
can also be coded both visually and
acoustically.

10. 2. Storage and Memory
• This concerns the nature of memory stores, i.e.
where the information is stored, how long the
memory lasts for (duration), how much can be
stored at any time (capacity) and what kind of
information is held.
• The way we store information affects the way we
retrieve it.
• There has been a significant amount of research
regarding the differences between Short Term
Memory (STM ) and Long Term Memory (LTM)

11. 2. Storage and Memory
• Most adults can store between 5 and 9 items
in their short-term memory.
• Miller put this idea forward and he called it
the magic number 7.
• He though that short-term memory capacity
was 7 (plus or minus 2) items because it only
had a certain number of “slots” in which items
could be stored.

12. 2. Storage and Memory
• Short-term memory: Miller didn’t specify the
amount of information that can be held in each
slot. Indeed, if we can “chunk” information
together we can store a lot more information in
our short-term memory.
• In contrast the capacity of LTM is thought to be
unlimited.
• Information can only be stored for a brief
duration in STM (0-30 seconds), but LTM can last
a lifetime.

13. 3. Retrieval and Memory
• This refers to getting information out storage.
If we can’t remember something, it may be
because we are unable to retrieve it.
• When we are asked to retrieve something
from memory, the differences between STM
and LTM become very clear.

14. 3. Retrieval and Memory
• STM is stored and retrieved sequentially. For
example, if a group of participants are given a list
of words to remember, and then asked to recall
the fourth word on the list, participants go
through the list in the order they heard it in order
to retrieve the information.
• LTM is stored and retrieved by association. This
is why you can remember what you went upstairs
for if you go back to the room where you first
thought about it.

15. 3. Retrieval and Memory
• Organizing information can help aid
retrieval. You can organize information in
sequences (such as alphabetically, by size or by
time).
• Imagine a patient being discharged form hospital
whose treatment involved taking various pills at
various times, changing their dressing and doing
exercises. If the doctor gives these instructions in
the order which they must be carried out
throughout the day (i.e. in sequence of time), this
will help the patient remember them.

16. The multi store model
• The multi store model (Atkinson and Shiffrin,
1968) is a classic model of memory. It is
sometimes called the modal model or the dual
process model.
• Atkinson and Shiffrin (1968) suggest that
memory is made up of a series of stores.

18. The multi store model
(Atkinson and Shiffrin 1968)
• The multi store model (Atkinson and Shiffrin 1968)
describes memory in terms of information flowing
through a system.
• Information is detected by the sense organs and enters
the sensory memory.
• If attended to this information enters the short term
memory.
• Information from the STM is transferred to the long-
term memory only if that information is rehearsed.
• If rehearsal does not occur, then information is
forgotten, lost from short term memory through the
processes of displacement or decay.

19. The multi store model

20. Sensory Memory
• Duration: ¼ to ½ second
• Capacity: all sensory experience (v. larger
capacity)
• Encoding: sense specific (e.g. different stores
for each sense)

21. Short term memory
• Duration: 15 and 30 seconds
• Capacity: 7 +/- 2 items
• Encoding: mainly auditory

22. Long term memory
• Duration: Unlimited
• Capacity: Unlimited
• Encoding: Mainly Semantic (but can be visual
and auditory)

23. Short Term Memory
by Saul McLeod published 2009
Short term memory has three key aspects:
1. limited capacity (only about 7 items can be
stored at a time)
2. limited duration (storage is very fragile and
information can be lost with distraction or
passage of time)
3. encoding (primarily acoustic, even translating
visual information into sounds).

24. Short Term Memory
• There are two ways in which capacity is tested, one
being span, the other being recency effect.
• Miller’s (1956) Magic number 7 (plus or minus two)
provides evidence for the capacity of short term
memory.
• Most adults can store between 5 and 9 items in their
short-term memory. This idea was put forward by
Miller (1956) and he called it the magic number 7. He
though that short term memory could hold 7 (plus or
minus 2 items) because it only had a certain number of
“slots” in which items could be stored.

25. Short Term Memory
• The duration of short term memory seems to
be between 15 and 30 seconds, according to
Atkinson and Shiffrin (1971).
• Items can be kept in short term memory by
repeating them verbally (acoustic encoding), a
process known as rehearsal.

26. Short Term Memory
• Using a technique called the Brown-Peterson
technique which prevents the possibility of
retrieval by having participants count backwards
in 3s, Peterson and Peterson 1959 showed that
the longer the delay, the less information is
recalled.
• The rapid loss of information from memory when
rehearsal is prevented is taken as an indication of
short term memory having a limited duration.

27. Why We Remember What We
Remember
• Short Term Memory. There are typically six reasons
why information is stored in our short term memory.
• 1. primacy effect information that occurs first is
typically remembered better than information
occurring later. When given a list of words or numbers,
the first word or number is usually remembered due to
rehearsing this more than other information.
• 2. recency effect - often the last bit of information is
remembered better because not as much time has
past; time which results in forgetting.

28. • 3. distinctiveness - if something stands out from
information around it, it is often remembered
better. Any distinctive information is easier to
remember than that which is similar, usual, or
mundane.
• 4. frequency effect - rehearsal, as stated in the
first example, results in better
memory. Remember trying to memorize a
formula for your math class. The more you went
over it, the better you knew it.

29. • 5. associations - when we associate or attach
information to other information it becomes
easier to remember. Many of us use this strategy
in our professions and everyday life in the form of
acronyms .
• 6. reconstruction - sometimes we actually fill in
the blanks in our memory. In other words, when
trying to get a complete picture in our minds, we
will make up the missing parts, often without any
realization that this is occurring.

30. • Baddeley and Hitch (1974) have developed an
alternative model of short-term memory
which they call working memory.

32. The multi store model
• Environmental input sensory memory
(Attention) working memory
Rehearsal Retrieval
long term memory

33. working memory
• Working memory is STM. 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 co-ordinates the
operation of two subsystems:
1- phonological loop and
2- visuo-spatial sketchpad.

34. working memory
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.
• A. Visuo-Spatial Sketch Pad (inner eye):
Stores and processes information in a visual
or spatial form. The VSS is used for navigation.

35. • B. 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
1. Phonological Store (inner ear) – Linked to speech perception
Holds information in speech-based form (i.e. spoken words)
for 1-2 seconds.
2. Articulatory control process (inner voice) – Linked to speech
production. Used to rehearse and store verbal information
from the phonological store.

37. • The phonological loop is assumed to be
responsible for the manipulation of speech
based information.
• The visuo-spatial sketchpad is assumed to be
responsible for manipulating visual images.
• The model proposes that every component of
working memory has a limited capacity, and
also that the components are relatively
independent of each other.

38. Empirical Evidence for the Working
Memory Model
• What evidence is there that working memory exists,
that it is made up of a number of parts, that it
performs a number of different tasks?
• The working memory model makes the following two predictions:
• 1. If two tasks make use of the same component (of working
memory), they cannot be performed successfully together.
• 2. If two tasks make use of different components, it should be
possible to perform them as well as together as separately.

39. Key Study: Baddeley and Hitch (1976)
• Aim: To investigate if participants can use different
parts of working memory at the same time.
• Method: Conducted an experiment in which
participants were asked to perform two tasks at the
same time (dual task technique) - a digit span task
which required them to repeat a list of numbers, and a
verbal reasoning task which required them to answer
true or false to various questions (e.g. B is followed by
A?).

40. • Results: As the number of digits increased in the
digit span tasks, participants took longer to
answer the reasoning questions, but not much
longer - only fractions of a second. And, they
didn't make any more errors in the verbal
reasoning tasks as the number of digits increased.
• Conclusion: The verbal reasoning task made use
of the central executive and the digit span task
made use of the phonological loop.

41. The Central Executive
• The central executive is the most important
component of the model, although little is known
about how it functions.
• It is responsible for monitoring and coordinating
the operation of the slave systems (i.e. visuo-
spatial sketch pad and phonological loop) and
relates them to long term memory (LTM).
• The central executive decides which information
is attended to and which parts of the working
memory to send that information to be dealt
with.

42. The Central Executive
• The central executive decides what working
memory pays attention to.
• For example, two activities sometimes come
into conflict such as driving a car and talking.
Rather than hitting a cyclist who is wobbling
all over the road, it is preferable to stop
talking and concentrate on driving. The central
executive directs attention and gives priority
to particular activities.

43. The Central Executive
• Baddeley suggests that the central executive acts
more like a system which controls attentional
processes rather than as a memory store.
• This is unlike the phonological loop and the visuo-
spatial sketchpad, which are specialized storage
systems.
• The central executive enables the working
memory system to selectively attend to some
stimuli and ignore others.

44. The Central Executive
• Baddeley (1986, 1999) uses the metaphor of a
company boss to describe the way in which
the central executive operates.
• The company boss makes decisions about
which issues deserve attention and which
should be ignored. They also select strategies
for dealing with problems, but like any person
in the company, the boss can only do a limited
number of things at the same time.

45. The Central Executive
• The boss of a company will collect information
from a number of different sources. If we
continue applying this metaphor, then we can
see the central executive in working memory
integrating (i.e. combining) information from
two assistants (the phonological loop and the
visuo-spatial sketchpad) and also drawing on
information held in a large database (long-
term memory).

46. The phonological loop

47. The phonological loop
• The phonological loop is the part of working
memory that deals with spoken and written
material. It consists of two parts.
• 1. The phonological store (linked to speech
perception) acts as an inner ear and holds
information in speech-based form (i.e. spoken
words) for 1-2 seconds. Spoken words enter the
store directly. Written words must first be
converted into an articulatory (spoken) code
before they can enter the phonological store.

48. The phonological loop
• 2. The articulatory control process (linked to
speech production) acts like an inner voice
rehearsing information from the phonological
store. It circulates information round and
round like a tape loop. This is how we
remember a telephone number we have just
heard. As long as we keep repeating it, we can
retain the information in working memory.

49. The phonological loop
• The articulatory control process also converts
written material into an articulatory code and
transfers it to the phonological store.

50. The Visuo-Spatial Sketchpad
• The visuo-spatial sketchpad (inner eye) deals
with visual and spatial information.
• Visual information refers to what things look
like. It is likely that the visuo-spatial sketchpad
plays an important role in helping us keep
track of where we are in relation to other
objects as we move through our environment
(Baddeley, 1997).

51. The Visuo-Spatial Sketchpad
• As we move around, our position in relation to
objects is constantly changing and it is
important that we can update this
information.
• For example, being aware of where we are in
relation to desks, chairs and tables when we
are walking around a classroom means that
we don't bump into things too often!

52. The Visuo-Spatial Sketchpad
• The sketchpad also displays and manipulates
visual and spatial information held in long-term
memory.
• For example, the spatial layout of your house is
held in LTM. Try answering this question: How
many windows are there in the front of your
house? You probably find yourself picturing the
front of your house and counting the windows.
An image has been retrieved from LTM and
pictured on the sketchpad.

53. The Visuo-Spatial Sketchpad
• Evidence suggests that working memory uses two
different systems for dealing with visual and
verbal information.
• A visual processing task and a verbal processing
task can be performed at the same time. It is
more difficult to perform two visual tasks at the
same time because they interfere with each other
and performance is reduced. The same applies to
performing two verbal tasks at the same time.

54. The Visuo-Spatial Sketchpad
• This supports the view that the phonological
loop and the sketchpad are separate systems
within working memory.

55. Evaluation of Working Memory
• Researchers today generally agree that short-
term memory is made up of a number of
components or subsystems. The working
memory model has replaced the idea of a
unitary (one part) STM as suggested by the
multistore model.

56. Evaluation of Working Memory
• The working memory model explains a lot
more than the multistore model.
• It makes sense of a range of tasks - verbal
reasoning, comprehension, reading, problem
solving and visual and spatial processing. And
the model is supported by considerable
experimental evidence.

57. Evaluation of Working Memory
The working memory applies to real life tasks:
- Reading (phonological loop)
- Problem solving (central executive)
- Navigation (visual and spatial processing)

58. Evaluation of Working Memory
• The KF Case Study supports the Working
Memory Model. KF suffered brain damage
from a motorcycle accident that damaged his
short-term memory. KF's impairment was
mainly for verbal information - his memory for
visual information was largely unaffected. This
shows that there are separate STM
components for visual information (VSS) and
verbal information (phonological loop).

59. Evaluation of Working Memory
• Working memory is supported by dual task
studies (Baddeley and Hitch, 1976).
• The working memory model does not over
emphasize the importance of rehearsal for
STM retention, in contrast to the multi-store
model.

60. Weaknesses of working memory model
• Lieberman criticizes the working memory
model as the visuo-spatial sketchpad (VSS)
implies that all spatial information was first
visual (they are linked). However, Lieberman
points out that blind people have excellent
spatial awareness although they have never
had any visual information. Lieberman argues
that the VSS should be separated into two
different components: one for visual
information and one for spatial.

61. Weaknesses of working memory model
• There is little direct evidence for how the central
executive works and what it does. The capacity
of the central executive has never been
measured.
• Working memory only involves STM so it is not a
comprehensive model of memory (as it does not
include SM or LTM).
• The working memory model does not explain
changes in processing ability that occur as the
result of practice or time.

62. Long Term Memory
by Saul McLeod published 2010
• Theoretically, the capacity of long term
memory could be unlimited, the main
constraint on recall being accessibility rather
than availability.
• Duration might be a few minutes or a lifetime.
• Suggested encoding modes are semantic
(meaning) and visual (pictorial) in the main
but can be acoustic also.

63. Long Term Memory
• Bahrick et al (1975) investigated what they called
very long term memory (VLTM). Nearly 400
participants aged 17 – 74 were tested. There
were various tests including:
1. A free recall test, where participants tried to
remember names of people in a graduate class.
2. A photo recognition test, consisting of 50
pictures.
3. A name recognition test for ex-school friends.

64. Long Term Memory
• Participants who were tested within 15 years
of graduation were about 90% accurate in
identifying names and faces. After 48 years
they were accurate 80% for verbal and 70%
visual.
• Free recall was worse. After 15 years it was
60% and after 48 years it was 30% accurate.

65. Long Term Memory
• One of the earliest and most influential
distinctions was proposed by Tulving
(1972). He proposed a distinction between
episodic, semantic and procedural memory.

66. Long Term Memory
• Procedural memory is a part of the long-term
memory is responsible for knowing how to do
things, i.e. memory of motor skills.
• It does not involve conscious (i.e. it’s
unconscious - automatic) thought is not
declarative.
• For example, procedural memory would
involve knowledge of how to ride a bicycle.

67. Long Term Memory
• Semantic memory is a part of the long-term
memory responsible for storing information
about the world. This includes knowledge
about the meaning of words, as well as
general knowledge. For example, London is
the capital of England. It involves conscious
thought and is declarative.

68. Long Term Memory
• Episodic memory is a part of the long-term
memory responsible for storing information
about events (i.e. episodes) that we have
experienced in out lives. It involves conscious
thought and is declarative. An example would
be a memory of our 1st day at school.

69. Long Term Memory
• Cohen and Squire (1980) drew a distinction
between declarative knowledge and procedural
knowledge.
• Procedural knowledge involves “knowing how”
to do things. It included skills, such as “knowing
how” to playing the piano, ride a bike; tie your
shoes and other motor skills. It does not involve
conscious (i.e. automatic) thought. For example,
we brush our teeth with little or no awareness of
the skills involved.

70. Long Term Memory
• Declarative knowledge involves “knowing
that”, for example London is the capital of
England, zebras are animals, your mums
birthday etc. Recalling information from
declarative memory involves some degree of
conscious effort – information is consciously
brought to mind and “declared”.

71. Long Term Memory
• The knowledge that we hold in semantic and
episodic memories focuses on “knowing that”
something is the case (i.e. declarative).
• For example, we might have a semantic
memory for knowing that Paris is the capital
of France, and we might have an episodic
memory for knowing that we caught the bus
to college today.

72. Long Term Memory
• Evidence for the distinction between declarative
and procedural memory has come from research
on patients with amnesia.
• Typically, amnesic patients have great difficulty in
retaining episodic and semantic information
following the onset of amnesia. Their memory for
events and knowledge acquired before the onset
of the condition tends to remain intact, but they
can’t store new episodic or semantic memories.
In other words, it appears that their ability to
retain declarative information is impaired.

73. Long Term Memory
• However, their procedural memory appears to
be largely unaffected. They can recall skills
they have already learned (e.g. riding a bike)
and acquire new skills (e.g. learning to drive).

74. • categorize memory as being explicit, which is defined as
that involved in the conscious recall of information about
people, places, and things, or
• implicit, which is characterized by the nonconscious recall
of tasks such as motor skills.
• Explicit memory depends on the integrity of temporal lobe
and diencephalic structures such as the hippocampus,
subiculum, and entorhinal cortex.
• Implicit memory includes simple associative forms of
memory, such as classical conditioning, and nonassociative
forms, such as habituation, and relies on the integrity of
the cerebellum and basal ganglia (582).

75. Levels of Processing
by Saul McLeod published 2007
• The levels of processing model of memory
(Craik and Lockhart, 1972) was put forward
partly as a result of the criticism leveled at the
multi-store model.
• Instead of concentrating on the
stores/structures involved (i.e. short term
memory & long term memory), this theory
concentrates on the processes involved in
memory.

76. Levels of Processing
• Unlike the multi-store model it is a non-
structured approach. The basic idea is that
memory is really just what happens as a result
of processing information.
• Psychologists Craik and Lockhart propose that
memory is just a by-product of the depth of
processing of information and there is no clear
distinction between short term memory and
long term memory.

77. Levels of Processing
• Depth is defined as "the meaningfulness
extracted from the stimulus rather than in
terms of the number of analyses performed
upon it.”

78. We can process information in 3 ways:
• Shallow Processing
• - This takes two forms
• 1. Structural processing (appearance) which is
when we encode only the physical qualities of
something. E.g. the typeface of a word or
how the letters look.
• 2. Phonemic processing – which is when we
encode its sound.

79. • Shallow processing only involves maintenance
rehearsal (repetition to help us hold
something in the STM) and leads to fairly
short-term retention of information. This is
the only type of rehearsal to take place within
the multi-store model.

80. • Deep Processing
• - This involves
• 3. Semantic processing, which happens when
we encode the meaning of a word and relate
it to similar words with similar meaning.

81. • Deep processing involves elaboration
rehearsal which involves a more meaningful
analysis (e.g. images, thinking, associations
etc.) of information and leads to better recall.
For example, giving words a meaning or
linking them with previous knowledge.

82. Summary
• Levels of processing: The idea that the way
information is encoded affects how well it is
remembered. The deeper the level of
processing, the easier the information is to
recall.

84. Application of the Levels of
Processing Model in Real Life
• This explanation of memory is useful in
everyday life because it highlights the way in
which elaboration, which requires deeper
processing of information, can aid memory.
Three examples of this are.

85. • • Reworking – putting information in your own
words or talking about it with someone else.
• Method of loci – when trying to remember a
list of items, linking each with a familiar place or
route.
• Imagery – by creating an image of something
you want to remember, you elaborate on it and
encode it visually (i.e. a mind map).

86. • The above examples could all be used to
revise psychology using semantic processing
(e.g. explaining memory models to your mum,
using mind maps etc.) and should result in
deeper processing through using elaboration
rehearsal. Consequently more information
will be remembered (and recalled) and better
exam results should be achieved.

87. • Further Information
• Memory
• Short Term Memory
• Long Term Memory
• Multi-Store Model
• Levels of Processing Model
• Working Memory Model
• How does working memory work in the classroom?
• Visual and Auditory Working Memory Capacity
• Is Working Memory Still Working
• Working Memory Model

88. Forgetting
by Saul McLeod published 2008
• Why do we forget? There are two simple
answers to this question.
First, the memory has disappeared - it is no
longer available.
Second, the memory is still stored in the memory
system but, for some reason, it cannot be
retrieved.
• The first answer is more likely to be applied to
forgetting in short term memory, the second to
forgetting in long term memory.

89. Forgetting
• Forgetting information from short term
memory (STM) can be explained using the
theories of trace decay and displacement.
• Forgetting from long term memory (LTM) can
be explained using the theories of
interference and lack of consolidation.

90. Trace Decay Theory of Forgetting
(STM)
• This theory relates to both short term
memory and long term memory, and also
relates to lack of availability.
• This theory suggests short term memory can
only hold information for between 15 and 30
seconds unless it is rehearsed. After this time
the information decays (fades away).

91. Trace Decay Theory
• This explanation of forgetting in short term
memory assumes that memories leave a trace in
the brain.
• A trace is some form of physical and/or chemical
change in the nervous system.
• Trace decay theory states that forgetting occurs
as a result of the automatic decay or fading of the
memory trace.
• Trace decay theory focuses on time and the
limited duration of short term memory.

92. Trace Decay Theory
• memory tends to get worse the longer the
delay between learning and recall
• The longer the time, the more the memory
trace decays and as a consequence more
information is forgotten.

93. Trace Decay Theory
• in any real-life situation, the time between
learning something and recalling it will be
filled with all kinds of different events. This
makes it very difficult to be sure that any
forgetting which takes place is the result of
decay rather than a consequence of the
intervening events.

94. Trace Decay Theory
• Support for the idea that forgetting from
short-term memory might be the result of
decay over time came from research carried
out by Brown (1958) in the United Kingdom,
and Peterson and Peterson (1959) in the
United States.
• The technique they developed has become
known as the Brown-Peterson task.

95. Key Study: Peterson and Peterson
(1959) – Duration of STM
• Aim: They wanted to test their hypothesis that
information was held in the STM for only
around 20 seconds, after that it disappears if
rehearsal is prevented. Therefore aiming to
prove that the duration of the STM is only
around 20 seconds. Also, to investigate if
information is lost from STM through decay.

96. • Method: Participants were presented with
sets of trigrams (nonsense syllables in sets of
three, e.g. BCM) which they were then asked
to recall in order after a delay of 3, 6, 9, 12, 15
and 18 seconds. An experimental method was
used: The IV was the time delay, and the DV
was the number of trigrams recalled.

97. • Participants were given an interference task of
counting backwards in threes from a random
three-digit number to prevent rehearsal
(known as the Brown-Peterson technique).
• Recall had to be 100% accurate and in the
correct order in order for it to count as
correctly recalled.

98. • Results: The percentage recall was:
• After 3 seconds = 80%
• After 6 seconds = 50%
• After 18 seconds = less than 10%
• Recall decreases steadily between 3 and 18
seconds suggesting that the duration of the STM
is not much more than 18 seconds.

99. • Conclusion: The memory trace in the STM has
just about disappeared after 18 seconds.
Information held in the STM is quickly lost
without rehearsal.
• This supports the hypothesis that the duration of
the STM is limited to approximately 20 seconds.
• They also concluded that this is evidence that the
STM is distinct from the LTM as the LTM has a
much longer duration (i.e. the results also
support the multi-store model).

100. Trace Decay Theory
• Peterson and Peterson (1959) explained this
rapid loss in terms of trace decay. The memory
trace fades over time until it disappears
completely. At this point, information is
forgotten.

101. Displacement from Short Term
Memory (STM)
• Displacement seeks to explain forgetting in
short term memory, and suggests it’s due to a
lack of availability.
• The short-term memory store in Atkinson &
Shiffrin's (1968) model of memory was
assumed to have certain characteristics,
including a limited capacity, and if information
was not rehearsed, it would be forgotten.

102. Displacement from Short Term
Memory (STM)
• Displacement theory provides a very simple
explanation of forgetting. Because of its limited
capacity, suggested by Miller to be 7+/- 2 items,
STM can only hold small amounts of information.
• When STM is 'full', new information displaces
or 'pushes out’ old information and takes its
place.
• The old information which is displaced is
forgotten in STM.

103. Displacement from Short Term
Memory (STM)
• It was also assumed that the information that
had been in the short-term store for the
longest was the first to be displaced by new
information, similar to the way in which boxes
might fail off the end of a conveyor belt - as
new boxes are put on one end, the boxes
which have been on the conveyor belt the
longest drop off the end.

104. Displacement from Short Term
Memory (STM)
• Support for the view that displacement was
responsible for the loss of information from
short-term memory came from studies using the
'free-recall' method.
• A typical study would use the following
procedure: participants listen to a list of words
read out a steady rate, usually two seconds per
word; they are then asked to recall as many of
words as possible. They are free to recall the
words in any order, hence the term 'free recall'.

105. Displacement from Short Term
Memory (STM)
• The findings from studies using free recall are
fairly reliable and they produce similar results
on each occasion. If you take each item in the
list and calculate the probability of
participants recalling it (by averaging recall of
the word over all participants) and plot this
against the item's position in the list, it results
in the serial position curve (Figure 1)

106. Simplified representation of the serial
position curve for immediate recall

107. Displacement from Short Term
Memory (STM)
• Good recall of items at the beginning of the list is
referred to as the primacy effect and good recall
if items at the end of the list are referred to as
the recency effect.
• T he displacement theory of forgetting from
short-term memory can explain the recency
effect quite easily. The last few words that were
presented in the list have not yet been displaced
from short-term memory and so are available for
recall.

108. Displacement from Short Term
Memory (STM)
• The primacy effect can be explained using
Atkinson & Shiffrin's (1968) multi-store model
which proposes that information is transferred
into long-term memory by means of rehearsal.
• The first words in the list are rehearsed more
frequently because at the time they are
presented they do not have to compete with
other words for the limited capacity of the short-
term store.

109. Displacement from Short Term
Memory (STM)
• This means that words early in the list are
more likely to be transferred to long-term
memory. So the primacy effect reflects items
that are available for recall from long-term
memory.
• However, words in the middle of the list used
to be in short term memory until they were
pushed out - or displaced by the words at the
end of the list.

110. Interference (LTM)
• Interference theory states that forgetting
occurs because memories interfere with and
disrupt one another, in other words forgetting
occurs because of interference from other
memories (Baddeley, 1999).

111. Interference (LTM)
• 1. Proactive interference (pro=forward)
occurs when a person cannot remember new
information because it has been confused
with old information.
• 2. Retroactive interference (retro=backward)
occurs when you cannot remember old
information because new information has
interfered with it.

112. Interference (LTM)
• Previous learning can sometimes interfere
with new learning (e.g. difficulties we have
with foreign currency when travelling
abroad).
• Also new learning can sometimes cause
confusion with previous learning. (Starting
French may affect our memory of previously
learned Spanish vocabulary).

113. Interference
• Interference is thought to be more likely to
occur where the memories are similar, for
example: confusing old and new telephone
numbers.
• Students who study similar subjects at the
same time often experience interference.
Starting French may affect our memory of
previously learned Spanish vocabulary.

114. Interference (LTM)
• In the short term memory interference can
occur in the form of distractions so that we
don’t get the chance to process the
information properly in the first place. (e.g.
someone using a loud drill just outside the
door of the classroom.)

115. Lack of consolidation (LTM)
• The previous accounts of forgetting have
focused primarily on psychological evidence,
but memory also relies on biological
processes. For example, we can define a
memory trace as:
• 'some permanent alteration of the brain
substrate in order to represent some aspect
of a past experience'.

116. Lack of consolidation (LTM)
• When we take in new information, a certain
amount of time is necessary for changes to
the nervous system to take place – the
consolidation process – so that it is properly
recorded.
• During this period information is moved from
short term memory to the more permanent
long term memory.

117. Lack of consolidation (LTM)
• The brain consists of a vast number of cells
called neurons, connected to each other by
synapses. Synapses enable chemicals to be
passed from one neuron to another. These
chemicals, called neurotransmitters, can
either inhibit or stimulate the performance of
neurons.

118. Lack of consolidation (LTM)
• So if you can imagine a network of neurons all
connected via synapses, there will be a pattern of
stimulation and inhibition. It has been suggested
that this pattern of inhibition and stimulation can
be used as a basis for storing information.
• This process of modifying neurons in order form
new permanent memories is referred to as
consolidation (Parkin, 1993).

119. Lack of consolidation (LTM)
• There is evidence that the consolidation process
is impaired if there is damage to the
hippocampus.
• In 1953, HM had brain surgery to treat his
epilepsy, which had become extremely severe.
The surgery removed parts of his brain and
destroyed the hippocampus, and although it
relieved his epilepsy, it left him with a range of
memory problems.
• Although his STM functioned well, he was unable
to process information into LTM.

120. Lack of consolidation (LTM)
• The main problem experienced by HM is his
inability to remember and learn new things.
This inability to form new memories is
referred to as anterograde amnesia.
• However, of interest in our understanding of
the duration of the process of consolidation is
HM's memory for events before his surgery.

121. Lack of consolidation (LTM)
• In general, his memory for events before the
surgery remains intact, but he does have some
memory loss for events which occurred in the
two years leading up to surgery.

122. Lack of consolidation (LTM)
• Pinel (1993) suggests that this challenges Hebb's
(1949) idea that the process of consolidation
takes approximately 30 minutes. The fact that
HM's memory is disrupted for the two-year
period leading up to the surgery indicates that
the process of consolidation continues for a
number of years.
• Finally, aging can also impair our ability to
consolidate information.

123. Retrieval failure theory (LTM)
• Retrieval failure is where the information is in
long term memory, but cannot be accessed.
• Such information is said to be available (i.e. it
is still stored) but not accessible (i.e. it cannot
be retrieved).
• It cannot be accessed because the retrieval
cues are not present.

124. Retrieval failure theory (LTM)
• When we store a new memory we also store
information about the situation and these are
known as retrieval cues. When we come into the
same situation again, these retrieval cues can
trigger the memory of the situation.
Retrieval cues can be:
• External / Context - in the environment, e.g.
smell, place etc.
• Internal / State- inside of us, e.g. physical,
emotional, mood, drunk etc.

125. Retrieval failure theory (LTM)
• Tulving (1974) argued that information would be
more readily retrieved if the cues present when
the information was encoded were also present
when its retrieval is required.
• For example, if you proposed to your partner
when a certain song was playing on the radio, you
will be more likely to remember the details of the
proposal when you hear the same song
again. The song is a retrieval cue - it was present
when the information was encoded and
retrieved.

126. Retrieval failure theory (LTM)
• Tulving suggested that information about the
physical surroundings (external context) and
about the physical or psychological state of the
learner (internal context) is stored at the same
time as information is learned.
• Reinstating the state or context makes recall
easier by providing relevant information, while
retrieval failure occurs when appropriate cues are
not present. For example, when we are in a
different context (i.e. situation) or state.

127. Context (external) Dependent
Forgetting
• Retrieval cues may be based on context-the
setting or situation in which information is
encoded and retrieved.
• Evidence indicates that retrieval is more likely
when the context at encoding matches the
context at retrieval.
• Examples include a particular room, driving
along a motorway, a certain group of people, a
rainy day and so on.

128. Context (external) Dependent
Forgetting
• You may have experienced the effect of
context on memory if you have ever visited a
place where you once lived (or an old school).
• Often such as visit helps people recall lots of
experiences about the time they spent there
which they did not realize were stored in their
memory.

129. State (internal) dependent cues
• The basic idea behind state-dependent retrieval is
that memory will be best when a person's
physical or psychological state is similar at
encoding and retrieval.
• For example, if someone tells you a joke on
Saturday night after a few drinks, you'll be more
likely to remember it when you're in a similar
state - at a later date after a few more
drinks. Stone cold sober on Monday morning,
you'll be more likely to forget the joke.

130. Context (external) Dependent
Forgetting
• State Retrieval clues may be based on state-
the physical or psychological state of the
person when information is encoded and
retrieved.
• For example, a person may be alert, tired,
happy, sad, drunk or sober when the
information was encoded. They will be more
likely to retrieve the information when they
are in a similar state.

131. Context (external) Dependent
Forgetting
• People tend to remember material better
when there is a match between their mood at
learning and at retrieval.
• The effects are stronger when the participants
are in a positive mood than a negative mood.
• They are also greater when people try to
remember events having personal relevance.

132. Measures of retention
Measures of retention. Memories may be retrieved in three
ways.
• recall: remembering of previously learned information
– free recall: recall of items in any order
– serial recall: recall of items in the order in which they were
learned
– paired associate recall: recall of a second item based on a cue
supplied by a first item
• recognition: identification of previously learned
information (as, for example from a number of answer
choices in a multiple-choice test)
• reconstruction: rebuilding of a scenario from certain
remembered details

133. Amnesia
• is the inability to remember events from the past
because of a psychological trauma ( psychogenic
amnesia) or a physiological trauma ( organic amnesia),
such as brain damage resulting from a blow to the
head. The memory loss is usually limited to a specific
period.
• Retrograde amnesia is the inability to remember
happenings that preceded the traumatic event
producing the amnesia.
• Anterograde amnesia is the inability to remember
happenings that occur after a traumatic event.

134. Amnesia
• People sometimes forget things because they
find them too unpleasant to think about.
• Such an occurrence is called motivated
forgetting.
• Sigmund Freud attributed many memory
failures, particularly involving painful
childhood experiences, to repression (the
process of keeping disturbing thoughts or
feelings relegated to the unconscious).

135. Amnesia
• The repressed material can sometimes be
recalled through free association or hypnosis.
• The recovery of supposedly repressed
memories, such as those of childhood sexual
abuse, is controversial.

136. Biological Substrates in Memory
• Although much information exists on the
connection between memory and biology, it is
far from complete.
• At the neuron level, a deficiency of the
neurotransmitter acetylcholine is a factor in
the dementia known as Alzheimer's disease
(administration of the neurotransmitter has
slowed the disease's progress but not
prevented it).

137. • Reduced levels of the neurotransmitter
glutamate have also been associated with the
disorder.
• Serotonin, another neurotransmitter, is also
thought to be important in memory functioning.
• Eric Kandel and James Schwartz, in a study of sea
snails, found that serotonin is released as they
learn.
• At the structural level, damage to the
hippocampus, part of the limbic system, has
been associated with memory difficulties.