NCERT Textbook: Human Memory | Psychology for UPSC Optional (Notes) PDF Download

 Page 1


Chapter
6
Human Memory Human Memory Human Memory Human Memory Human Memory
Human Memory Human Memory Human Memory Human Memory Human Memory
Introduction
Nature of Memory
Information Processing Approach : The Stage Model
Memory Systems : Sensory, Short-term and Long-term Memories
Working Memory (Box 6.1)
Levels of Processing
Types of Long-term Memory
Declarative and Procedural; Episodic and Semantic
Long-term Memory Classification (Box 6.2)
Methods of Memory Measurement (Box 6.3)
Nature and Causes of Forgetting
Forgetting due to Trace Decay, Interference and Retrieval Failure
Repressed Memories (Box 6.4)
Enhancing Memory
Mnemonics using Images and Organisation
Key Terms
Summary
Review Questions
Project Ideas
Contents
• understand the nature of memory,
• distinguish between different types of memory,
• understand the nature and causes of forgetting, and
• learn the strategies for improving memory.
After reading this chapter, you would be able to
The advantage of bad
memory is that one
enjoys several times,
the same good things
for the first time.
– Friedrich Nietzsche
Rationalised 2023-24
Page 2


Chapter
6
Human Memory Human Memory Human Memory Human Memory Human Memory
Human Memory Human Memory Human Memory Human Memory Human Memory
Introduction
Nature of Memory
Information Processing Approach : The Stage Model
Memory Systems : Sensory, Short-term and Long-term Memories
Working Memory (Box 6.1)
Levels of Processing
Types of Long-term Memory
Declarative and Procedural; Episodic and Semantic
Long-term Memory Classification (Box 6.2)
Methods of Memory Measurement (Box 6.3)
Nature and Causes of Forgetting
Forgetting due to Trace Decay, Interference and Retrieval Failure
Repressed Memories (Box 6.4)
Enhancing Memory
Mnemonics using Images and Organisation
Key Terms
Summary
Review Questions
Project Ideas
Contents
• understand the nature of memory,
• distinguish between different types of memory,
• understand the nature and causes of forgetting, and
• learn the strategies for improving memory.
After reading this chapter, you would be able to
The advantage of bad
memory is that one
enjoys several times,
the same good things
for the first time.
– Friedrich Nietzsche
Rationalised 2023-24
Psychology
96
process consisting of three independent,
though interrelated stages. These are
encoding, storage, and retrieval. Any
information received by us necessarily goes
through these stages.
(a) Encoding is the first stage which refers to a
process by which information is recorded and
registered for the first time so that it becomes
usable by our memory system. Whenever an
external stimulus impinges on our sensory
organs, it generates neural impulses. These are
received in different areas of our brain for
further processing. In encoding, incoming
information is received and some meaning is
NATURE OF MEMORY
Memory refers to retaining and recalling
information over a period of time, depending
upon the nature of cognitive task you are
required to perform. It might be necessary to
hold an information for a few seconds. For
example, you use your memory to retain an
unfamiliar telephone number till you have
reached the telephone instrument to dial, or
for many years you still remember the
techniques of addition and subtraction which
you perhaps learned during your early
schooling. Memory is conceptualised as a
All of us are aware of the tricks that memory plays on us throughout our lives.
Have you ever felt embarrassed because you could not remember the name of a
known person you were talking to? Or anxious and helpless because everything
you memorised well the previous day before taking your examination has suddenly
become unavailable? Or felt excited because you can now flawlessly recite lines of
a famous poem you had learnt as a child? Memory indeed is a very fascinating yet
intriguing human faculty. It functions to preserve our sense of who we are, maintains
our interpersonal relationships and helps us in solving problems and taking
decisions. Since memory is central to almost all cognitive processes such as
perception, thinking and problem solving, psychologists have attempted to
understand the manner in which any information is committed to memory, the
mechanisms through which it is retained over a period of time, the reasons why it is
lost from memory, and the techniques which can lead to memory improvement. In
this chapter, we shall examine all these aspects of memory and understand various
theories which explain the mechanisms of memory.
The history of psychological research on memory spans over hundred years.
The first systematic exploration of memory is credited to Hermann Ebbinghaus, a
German psychologist of late nineteenth century (1885). He carried out many
experiments on himself and found that we do not forget the learned material at an
even pace or completely. Initially the rate of forgetting is faster but eventually it
stabilises. There are other psychologists who have influenced memory research in
a major way. We shall review their contributions in this chapter at appropriate
places.
Introduction
Rationalised 2023-24
Page 3


Chapter
6
Human Memory Human Memory Human Memory Human Memory Human Memory
Human Memory Human Memory Human Memory Human Memory Human Memory
Introduction
Nature of Memory
Information Processing Approach : The Stage Model
Memory Systems : Sensory, Short-term and Long-term Memories
Working Memory (Box 6.1)
Levels of Processing
Types of Long-term Memory
Declarative and Procedural; Episodic and Semantic
Long-term Memory Classification (Box 6.2)
Methods of Memory Measurement (Box 6.3)
Nature and Causes of Forgetting
Forgetting due to Trace Decay, Interference and Retrieval Failure
Repressed Memories (Box 6.4)
Enhancing Memory
Mnemonics using Images and Organisation
Key Terms
Summary
Review Questions
Project Ideas
Contents
• understand the nature of memory,
• distinguish between different types of memory,
• understand the nature and causes of forgetting, and
• learn the strategies for improving memory.
After reading this chapter, you would be able to
The advantage of bad
memory is that one
enjoys several times,
the same good things
for the first time.
– Friedrich Nietzsche
Rationalised 2023-24
Psychology
96
process consisting of three independent,
though interrelated stages. These are
encoding, storage, and retrieval. Any
information received by us necessarily goes
through these stages.
(a) Encoding is the first stage which refers to a
process by which information is recorded and
registered for the first time so that it becomes
usable by our memory system. Whenever an
external stimulus impinges on our sensory
organs, it generates neural impulses. These are
received in different areas of our brain for
further processing. In encoding, incoming
information is received and some meaning is
NATURE OF MEMORY
Memory refers to retaining and recalling
information over a period of time, depending
upon the nature of cognitive task you are
required to perform. It might be necessary to
hold an information for a few seconds. For
example, you use your memory to retain an
unfamiliar telephone number till you have
reached the telephone instrument to dial, or
for many years you still remember the
techniques of addition and subtraction which
you perhaps learned during your early
schooling. Memory is conceptualised as a
All of us are aware of the tricks that memory plays on us throughout our lives.
Have you ever felt embarrassed because you could not remember the name of a
known person you were talking to? Or anxious and helpless because everything
you memorised well the previous day before taking your examination has suddenly
become unavailable? Or felt excited because you can now flawlessly recite lines of
a famous poem you had learnt as a child? Memory indeed is a very fascinating yet
intriguing human faculty. It functions to preserve our sense of who we are, maintains
our interpersonal relationships and helps us in solving problems and taking
decisions. Since memory is central to almost all cognitive processes such as
perception, thinking and problem solving, psychologists have attempted to
understand the manner in which any information is committed to memory, the
mechanisms through which it is retained over a period of time, the reasons why it is
lost from memory, and the techniques which can lead to memory improvement. In
this chapter, we shall examine all these aspects of memory and understand various
theories which explain the mechanisms of memory.
The history of psychological research on memory spans over hundred years.
The first systematic exploration of memory is credited to Hermann Ebbinghaus, a
German psychologist of late nineteenth century (1885). He carried out many
experiments on himself and found that we do not forget the learned material at an
even pace or completely. Initially the rate of forgetting is faster but eventually it
stabilises. There are other psychologists who have influenced memory research in
a major way. We shall review their contributions in this chapter at appropriate
places.
Introduction
Rationalised 2023-24
Chapter 6 • Human Memory
97
derived. It is then represented in a way so that
it can be processed further.
(b) Storage is the second stage of memory.
Information which was encoded must also be
stored so that it can be put to use later. Storage,
therefore, refers to the process through which
information is retained and held over a period
of time.
(c) Retrieval is the third stage of memory.
Information can be used only when one is able
to recover it from her/his memory. Retrieval
refers to bringing the stored information to her/
his awareness so that it can be used for
performing various cognitive tasks such as
problem solving or decision-making. It may be
interesting to note that memory failure can
occur at any of these stages. You may fail to
recall an information because you did not
encode it properly, or the storage was weak so
you could not access or retrieve it when
required.
INFORMATION PROCESSING APPROACH :
THE STAGE MODEL
Initially, it was thought that memory is the
capacity to store all information that we acquire
through learning and experience. It was seen
as a vast storehouse where all information that
we knew was kept so that we could retrieve
and use it as and when needed. But with the
advent of the computer, human memory came
to be seen as a system that processes
information in the same way as a computer
does. Both register, store, and manipulate large
amount of information and act on the basis of
the outcome of such manipulations. If you
have worked on a computer then you would
know that it has a temporary memory (random
access memory or RAM) and a permanent
memory (e.g., a hard disk). Based on the
programme commands, the computer
manipulates the contents of its memories and
displays the output on the screen. In the same
way, human beings too register information,
store and manipulate the stored information
depending on the task that they need to
perform. For example, when you are required
to solve a mathematical problem, the memory
relating to mathematical operations, such as
division or subtraction are carried out,
activated and put to use, and receive the
output (the problem solution). This analogy led
to the development of the first model of
memory, which was proposed by Atkinson and
Shiffrin in 1968. It is known as Stage Model.
MEMORY SYSTEMS : SENSORY, SHORT-TERM
AND LONG-TERM MEMORIES
According to the Stage Model, there are three
memory systems : the Sensory Memory, the
Short-term Memory and the Long-term
Memory. Each of these systems have different
features and perform different functions with
respect to the sensory inputs (see Fig.6.1). Let
us examine what these systems are:
Fig.6.1 : The Stage Model of Memory
Information
Sensory Memory
Iconic (Sight)
Echoic (Sound)
and other senses
Store Capacity -
large
Duration - less
than one second
Attention
Short-term
Memory
Store Capacity -
small
Duration - less
than 30 seconds
Elaborative
Rehearsals
Long-term
Memory
Permanent
Store Capacity -
unlimited
Duration - upto
a lifetime
Rationalised 2023-24
Page 4


Chapter
6
Human Memory Human Memory Human Memory Human Memory Human Memory
Human Memory Human Memory Human Memory Human Memory Human Memory
Introduction
Nature of Memory
Information Processing Approach : The Stage Model
Memory Systems : Sensory, Short-term and Long-term Memories
Working Memory (Box 6.1)
Levels of Processing
Types of Long-term Memory
Declarative and Procedural; Episodic and Semantic
Long-term Memory Classification (Box 6.2)
Methods of Memory Measurement (Box 6.3)
Nature and Causes of Forgetting
Forgetting due to Trace Decay, Interference and Retrieval Failure
Repressed Memories (Box 6.4)
Enhancing Memory
Mnemonics using Images and Organisation
Key Terms
Summary
Review Questions
Project Ideas
Contents
• understand the nature of memory,
• distinguish between different types of memory,
• understand the nature and causes of forgetting, and
• learn the strategies for improving memory.
After reading this chapter, you would be able to
The advantage of bad
memory is that one
enjoys several times,
the same good things
for the first time.
– Friedrich Nietzsche
Rationalised 2023-24
Psychology
96
process consisting of three independent,
though interrelated stages. These are
encoding, storage, and retrieval. Any
information received by us necessarily goes
through these stages.
(a) Encoding is the first stage which refers to a
process by which information is recorded and
registered for the first time so that it becomes
usable by our memory system. Whenever an
external stimulus impinges on our sensory
organs, it generates neural impulses. These are
received in different areas of our brain for
further processing. In encoding, incoming
information is received and some meaning is
NATURE OF MEMORY
Memory refers to retaining and recalling
information over a period of time, depending
upon the nature of cognitive task you are
required to perform. It might be necessary to
hold an information for a few seconds. For
example, you use your memory to retain an
unfamiliar telephone number till you have
reached the telephone instrument to dial, or
for many years you still remember the
techniques of addition and subtraction which
you perhaps learned during your early
schooling. Memory is conceptualised as a
All of us are aware of the tricks that memory plays on us throughout our lives.
Have you ever felt embarrassed because you could not remember the name of a
known person you were talking to? Or anxious and helpless because everything
you memorised well the previous day before taking your examination has suddenly
become unavailable? Or felt excited because you can now flawlessly recite lines of
a famous poem you had learnt as a child? Memory indeed is a very fascinating yet
intriguing human faculty. It functions to preserve our sense of who we are, maintains
our interpersonal relationships and helps us in solving problems and taking
decisions. Since memory is central to almost all cognitive processes such as
perception, thinking and problem solving, psychologists have attempted to
understand the manner in which any information is committed to memory, the
mechanisms through which it is retained over a period of time, the reasons why it is
lost from memory, and the techniques which can lead to memory improvement. In
this chapter, we shall examine all these aspects of memory and understand various
theories which explain the mechanisms of memory.
The history of psychological research on memory spans over hundred years.
The first systematic exploration of memory is credited to Hermann Ebbinghaus, a
German psychologist of late nineteenth century (1885). He carried out many
experiments on himself and found that we do not forget the learned material at an
even pace or completely. Initially the rate of forgetting is faster but eventually it
stabilises. There are other psychologists who have influenced memory research in
a major way. We shall review their contributions in this chapter at appropriate
places.
Introduction
Rationalised 2023-24
Chapter 6 • Human Memory
97
derived. It is then represented in a way so that
it can be processed further.
(b) Storage is the second stage of memory.
Information which was encoded must also be
stored so that it can be put to use later. Storage,
therefore, refers to the process through which
information is retained and held over a period
of time.
(c) Retrieval is the third stage of memory.
Information can be used only when one is able
to recover it from her/his memory. Retrieval
refers to bringing the stored information to her/
his awareness so that it can be used for
performing various cognitive tasks such as
problem solving or decision-making. It may be
interesting to note that memory failure can
occur at any of these stages. You may fail to
recall an information because you did not
encode it properly, or the storage was weak so
you could not access or retrieve it when
required.
INFORMATION PROCESSING APPROACH :
THE STAGE MODEL
Initially, it was thought that memory is the
capacity to store all information that we acquire
through learning and experience. It was seen
as a vast storehouse where all information that
we knew was kept so that we could retrieve
and use it as and when needed. But with the
advent of the computer, human memory came
to be seen as a system that processes
information in the same way as a computer
does. Both register, store, and manipulate large
amount of information and act on the basis of
the outcome of such manipulations. If you
have worked on a computer then you would
know that it has a temporary memory (random
access memory or RAM) and a permanent
memory (e.g., a hard disk). Based on the
programme commands, the computer
manipulates the contents of its memories and
displays the output on the screen. In the same
way, human beings too register information,
store and manipulate the stored information
depending on the task that they need to
perform. For example, when you are required
to solve a mathematical problem, the memory
relating to mathematical operations, such as
division or subtraction are carried out,
activated and put to use, and receive the
output (the problem solution). This analogy led
to the development of the first model of
memory, which was proposed by Atkinson and
Shiffrin in 1968. It is known as Stage Model.
MEMORY SYSTEMS : SENSORY, SHORT-TERM
AND LONG-TERM MEMORIES
According to the Stage Model, there are three
memory systems : the Sensory Memory, the
Short-term Memory and the Long-term
Memory. Each of these systems have different
features and perform different functions with
respect to the sensory inputs (see Fig.6.1). Let
us examine what these systems are:
Fig.6.1 : The Stage Model of Memory
Information
Sensory Memory
Iconic (Sight)
Echoic (Sound)
and other senses
Store Capacity -
large
Duration - less
than one second
Attention
Short-term
Memory
Store Capacity -
small
Duration - less
than 30 seconds
Elaborative
Rehearsals
Long-term
Memory
Permanent
Store Capacity -
unlimited
Duration - upto
a lifetime
Rationalised 2023-24
Psychology
98
Sensory Memory
The incoming information first enters the
sensory memory. Sensory memory has a large
capacity. However, it is of very short duration,
i.e. less than a second. It is a memory system
that registers information from each of the
senses with reasonable accuracy. Often this
system is referred to as sensory memories or
sensory registers because information from all
the senses are registered here as exact replica
of the stimulus. If you have experienced visual
after-images  (the trail of light that stays after
the bulb is switched off) or when you hear
reverberations of a sound when the sound has
ceased, then you are familiar with iconic
(visual) or echoic (auditory) sensory registers.
Short-term Memory
You will perhaps agree that we do not attend
to all the information that impinge on our
senses. Information that is attended to enters
the second memory store called the short-term
memory (abbreviated as STM), which holds
small amount of information for a brief period
of time (usually for 30 seconds or less).
Atkinson and Shiffrin propose that
information in STM is primarily encoded
acoustically, i.e. in terms of sound and unless
rehearsed continuously, it may get lost from
the STM in less than 30 seconds. Note that
the STM is fragile but not as fragile as sensory
registers where the information decays
automatically in less than a second.
Long-term Memory
Materials that survive the capacity and
duration limitations of the STM finally enter
the long-term memory (abbreviated as LTM)
which has a vast capacity. It is a permanent
storehouse of all information that may be as
recent as what you ate for breakfast yesterday
to as distant as how you celebrated your sixth
birthday. It has been shown that once any
information enters the long-term memory
store it is never forgotten because it gets
encoded semantically, i.e. in terms of the
meaning that any information carries. What
you experience as forgetting is in fact retrieval
failure; for various reasons you cannot retrieve
the stored information. You will read about
retrieval related forgetting later in this chapter.
So far we have only discussed the structural
features of the stage model. Questions which
still remain to be addressed are how does
information travel from one store to another
and by what mechanisms it continues to stay
in any particular memory store. Let us examine
the answers to these questions.
How does information travel from one store
to another? As an answer to this question,
Atkinson and Shiffrin propose the notion of
control processes which function to monitor
the flow of information through various
In recent years, psychologists have suggested that
the short-term memory is not unitary, rather it may
consist of many components. This multi-
component view of short-term memory was first
proposed by Baddeley (1986) who suggested that
the short-term memory is not a passive storehouse
but rather a work bench that holds a wide variety
of memory materials that are constantly handled,
manipulated and transformed as people perform
various cognitive tasks. This work bench is called
the working memory. The first component of the
working memory is the phonological loop which
Box Box Box Box Box 6.1 W W W W Working Memory orking Memory orking Memory orking Memory orking Memory
holds a limited number of sounds and unless rehearsed
they decay within 2 seconds. The second component
visuospatial sketchpad stores visual and spatial
information and like phonological loop the capacity of
the sketchpad too is limited. The third component, which
Baddeley calls the Central Executive, organises
information from phonological loop, visuospatial
sketchpad as well as from the long-term memory. Like
a true executive, it allocates attentional resources to be
distributed to various information needed to perform a
given cognitive operation and monitors, plans, and
controls behaviour .
Rationalised 2023-24
Page 5


Chapter
6
Human Memory Human Memory Human Memory Human Memory Human Memory
Human Memory Human Memory Human Memory Human Memory Human Memory
Introduction
Nature of Memory
Information Processing Approach : The Stage Model
Memory Systems : Sensory, Short-term and Long-term Memories
Working Memory (Box 6.1)
Levels of Processing
Types of Long-term Memory
Declarative and Procedural; Episodic and Semantic
Long-term Memory Classification (Box 6.2)
Methods of Memory Measurement (Box 6.3)
Nature and Causes of Forgetting
Forgetting due to Trace Decay, Interference and Retrieval Failure
Repressed Memories (Box 6.4)
Enhancing Memory
Mnemonics using Images and Organisation
Key Terms
Summary
Review Questions
Project Ideas
Contents
• understand the nature of memory,
• distinguish between different types of memory,
• understand the nature and causes of forgetting, and
• learn the strategies for improving memory.
After reading this chapter, you would be able to
The advantage of bad
memory is that one
enjoys several times,
the same good things
for the first time.
– Friedrich Nietzsche
Rationalised 2023-24
Psychology
96
process consisting of three independent,
though interrelated stages. These are
encoding, storage, and retrieval. Any
information received by us necessarily goes
through these stages.
(a) Encoding is the first stage which refers to a
process by which information is recorded and
registered for the first time so that it becomes
usable by our memory system. Whenever an
external stimulus impinges on our sensory
organs, it generates neural impulses. These are
received in different areas of our brain for
further processing. In encoding, incoming
information is received and some meaning is
NATURE OF MEMORY
Memory refers to retaining and recalling
information over a period of time, depending
upon the nature of cognitive task you are
required to perform. It might be necessary to
hold an information for a few seconds. For
example, you use your memory to retain an
unfamiliar telephone number till you have
reached the telephone instrument to dial, or
for many years you still remember the
techniques of addition and subtraction which
you perhaps learned during your early
schooling. Memory is conceptualised as a
All of us are aware of the tricks that memory plays on us throughout our lives.
Have you ever felt embarrassed because you could not remember the name of a
known person you were talking to? Or anxious and helpless because everything
you memorised well the previous day before taking your examination has suddenly
become unavailable? Or felt excited because you can now flawlessly recite lines of
a famous poem you had learnt as a child? Memory indeed is a very fascinating yet
intriguing human faculty. It functions to preserve our sense of who we are, maintains
our interpersonal relationships and helps us in solving problems and taking
decisions. Since memory is central to almost all cognitive processes such as
perception, thinking and problem solving, psychologists have attempted to
understand the manner in which any information is committed to memory, the
mechanisms through which it is retained over a period of time, the reasons why it is
lost from memory, and the techniques which can lead to memory improvement. In
this chapter, we shall examine all these aspects of memory and understand various
theories which explain the mechanisms of memory.
The history of psychological research on memory spans over hundred years.
The first systematic exploration of memory is credited to Hermann Ebbinghaus, a
German psychologist of late nineteenth century (1885). He carried out many
experiments on himself and found that we do not forget the learned material at an
even pace or completely. Initially the rate of forgetting is faster but eventually it
stabilises. There are other psychologists who have influenced memory research in
a major way. We shall review their contributions in this chapter at appropriate
places.
Introduction
Rationalised 2023-24
Chapter 6 • Human Memory
97
derived. It is then represented in a way so that
it can be processed further.
(b) Storage is the second stage of memory.
Information which was encoded must also be
stored so that it can be put to use later. Storage,
therefore, refers to the process through which
information is retained and held over a period
of time.
(c) Retrieval is the third stage of memory.
Information can be used only when one is able
to recover it from her/his memory. Retrieval
refers to bringing the stored information to her/
his awareness so that it can be used for
performing various cognitive tasks such as
problem solving or decision-making. It may be
interesting to note that memory failure can
occur at any of these stages. You may fail to
recall an information because you did not
encode it properly, or the storage was weak so
you could not access or retrieve it when
required.
INFORMATION PROCESSING APPROACH :
THE STAGE MODEL
Initially, it was thought that memory is the
capacity to store all information that we acquire
through learning and experience. It was seen
as a vast storehouse where all information that
we knew was kept so that we could retrieve
and use it as and when needed. But with the
advent of the computer, human memory came
to be seen as a system that processes
information in the same way as a computer
does. Both register, store, and manipulate large
amount of information and act on the basis of
the outcome of such manipulations. If you
have worked on a computer then you would
know that it has a temporary memory (random
access memory or RAM) and a permanent
memory (e.g., a hard disk). Based on the
programme commands, the computer
manipulates the contents of its memories and
displays the output on the screen. In the same
way, human beings too register information,
store and manipulate the stored information
depending on the task that they need to
perform. For example, when you are required
to solve a mathematical problem, the memory
relating to mathematical operations, such as
division or subtraction are carried out,
activated and put to use, and receive the
output (the problem solution). This analogy led
to the development of the first model of
memory, which was proposed by Atkinson and
Shiffrin in 1968. It is known as Stage Model.
MEMORY SYSTEMS : SENSORY, SHORT-TERM
AND LONG-TERM MEMORIES
According to the Stage Model, there are three
memory systems : the Sensory Memory, the
Short-term Memory and the Long-term
Memory. Each of these systems have different
features and perform different functions with
respect to the sensory inputs (see Fig.6.1). Let
us examine what these systems are:
Fig.6.1 : The Stage Model of Memory
Information
Sensory Memory
Iconic (Sight)
Echoic (Sound)
and other senses
Store Capacity -
large
Duration - less
than one second
Attention
Short-term
Memory
Store Capacity -
small
Duration - less
than 30 seconds
Elaborative
Rehearsals
Long-term
Memory
Permanent
Store Capacity -
unlimited
Duration - upto
a lifetime
Rationalised 2023-24
Psychology
98
Sensory Memory
The incoming information first enters the
sensory memory. Sensory memory has a large
capacity. However, it is of very short duration,
i.e. less than a second. It is a memory system
that registers information from each of the
senses with reasonable accuracy. Often this
system is referred to as sensory memories or
sensory registers because information from all
the senses are registered here as exact replica
of the stimulus. If you have experienced visual
after-images  (the trail of light that stays after
the bulb is switched off) or when you hear
reverberations of a sound when the sound has
ceased, then you are familiar with iconic
(visual) or echoic (auditory) sensory registers.
Short-term Memory
You will perhaps agree that we do not attend
to all the information that impinge on our
senses. Information that is attended to enters
the second memory store called the short-term
memory (abbreviated as STM), which holds
small amount of information for a brief period
of time (usually for 30 seconds or less).
Atkinson and Shiffrin propose that
information in STM is primarily encoded
acoustically, i.e. in terms of sound and unless
rehearsed continuously, it may get lost from
the STM in less than 30 seconds. Note that
the STM is fragile but not as fragile as sensory
registers where the information decays
automatically in less than a second.
Long-term Memory
Materials that survive the capacity and
duration limitations of the STM finally enter
the long-term memory (abbreviated as LTM)
which has a vast capacity. It is a permanent
storehouse of all information that may be as
recent as what you ate for breakfast yesterday
to as distant as how you celebrated your sixth
birthday. It has been shown that once any
information enters the long-term memory
store it is never forgotten because it gets
encoded semantically, i.e. in terms of the
meaning that any information carries. What
you experience as forgetting is in fact retrieval
failure; for various reasons you cannot retrieve
the stored information. You will read about
retrieval related forgetting later in this chapter.
So far we have only discussed the structural
features of the stage model. Questions which
still remain to be addressed are how does
information travel from one store to another
and by what mechanisms it continues to stay
in any particular memory store. Let us examine
the answers to these questions.
How does information travel from one store
to another? As an answer to this question,
Atkinson and Shiffrin propose the notion of
control processes which function to monitor
the flow of information through various
In recent years, psychologists have suggested that
the short-term memory is not unitary, rather it may
consist of many components. This multi-
component view of short-term memory was first
proposed by Baddeley (1986) who suggested that
the short-term memory is not a passive storehouse
but rather a work bench that holds a wide variety
of memory materials that are constantly handled,
manipulated and transformed as people perform
various cognitive tasks. This work bench is called
the working memory. The first component of the
working memory is the phonological loop which
Box Box Box Box Box 6.1 W W W W Working Memory orking Memory orking Memory orking Memory orking Memory
holds a limited number of sounds and unless rehearsed
they decay within 2 seconds. The second component
visuospatial sketchpad stores visual and spatial
information and like phonological loop the capacity of
the sketchpad too is limited. The third component, which
Baddeley calls the Central Executive, organises
information from phonological loop, visuospatial
sketchpad as well as from the long-term memory. Like
a true executive, it allocates attentional resources to be
distributed to various information needed to perform a
given cognitive operation and monitors, plans, and
controls behaviour .
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Chapter 6 • Human Memory
99
memory stores. As suggested earlier, all
informations which our senses receive are not
registered; if that be the case, imagine the kind
of pressure that our memory system will have
to cope with. Only that information which is
attended to enters the STM from sensory
registers and in that sense, selective attention,
as you have already read in Chapter 5, is the
first control process that decides what will
travel from sensory registers to STM. Sense
impressions, which do not receive attention,
fade away quickly. The STM then sets into
motion another control process of
maintenance rehearsal to retain the
information for as much time as required. As
the name suggests, these kinds of rehearsals
simply maintain information through
repetition and when such repetitions
discontinue the information is lost. Another
control process, which operates in STM to
expand its capacity, is Chunking. Through
chunking it is possible to expand the capacity
of STM which is otherwise 7+2. For example,
if you are told to remember a string of digits
such as 194719492004 (note that the number
exceeds the capacity of STM), you may create
the chunks as 1947, 1949, and 2004 and
remember them as the year when India became
independent, the year when the Indian
Constitution was adopted, and the year when
the tsunami hit the coastal regions of India and
South East Asian countries.
From the STM, information enters the long-
term memory through elaborative rehearsals.
As against maintenance rehearsals, which are
carried through silent or vocal repetition, this
rehearsal attempts to connect the ‘to be
retained information’ to the already existing
information in long-term memory. For
example, the task of remembering the meaning
of the word ‘humanity’ will be easier if the
meanings of concepts such as ‘compassion’,
‘truth’ and ‘benevolence’ are already in place.
The number of associations you can create
around the new information will determine its
permanence. In elaborative rehearsals one
attempts to analyse the information in terms
of various associations it arouses. It involves
organisation of the incoming information in
as many ways as possible. You can expand
the information in some kind of logical
framework, link it to similar memories or else
can create a mental image. Figure 6.1, that
presents the stage model of memory, also
depicts the arrows to show the manner in
which information travels from one stage to
another.
Experiments, which were carried out to
test the stage model of memory, have produced
mixed results. While some experiments
unequivocally show that the STM and LTM
are indeed two separate memory stores, other
evidences have questioned their
distinctiveness. For example, earlier it was
shown that in the STM information is encoded
acoustically, while in LTM it is encoded
semantically, but later experimental evidences
show that information can also be encoded
semantically in STM and acoustically in LTM.
I. Try to remember the following list of digits
(individual digits)
                      1 9 2 5 4 9 8 1 1 2 1
Now try to memorise them in the following
groups:
                     1 9 25 49 81 121
Finally memorise them in the following
manner:
                     1
2
 3
2
 5
2
 7
2
 9
2
 11
2
What difference do you observe?
II. Read out the lists given below in a row at the
speed of one digit per second to your friend
and ask her/him to repeat all the digits in
the same order:
List Digits
1 (6 digits) 2-6-3-8-3-4
2 (7 digits) 7-4-8-2-4-1-2
3 (8 digits) 4-3-7-2-9-0-3-6
4 (10 digits) 9-2-4-1-7-8-2-6-5-3
5 (12 digits) 8-2-5-4-7-4-7-7-3-9-1-6
Remember that your friend will recall the
digits as soon as you finish the list. Note how
many digits are recalled. The memory score
of your friend will be the number of digits
correctly recalled by her/him. Discuss your
findings with your classmates and teacher.
Activity  Activity  Activity  Activity  Activity  6.1
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