Human memory, like memory in a computer, allows us to store information for later use.It seems that as much as we do remember, we forget even more. Forgetting isn’t really all that bad, and is in actuality, a pretty natural phenomenon. Imagine if you remembered every minute detail of every minute or every hour, of every day during your entire life, no matter how good, bad, or insignificant

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Memory And Forgetting

2. What is Memory?
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 Memory is clearly a central process in all aspects of behaviour
 It deals with the reproduction of events and experiences of
the past.
 A person or an animal experiences ease in relearning an
activity, which he had learnt previously. Yet forgetting is also
a common experience. In fact, a major part of what is learnt is
forgotten, and when we are required to remember it we tend
to reconstruct the past. For example, we may not remember
the complete story of a bad film. However, if a friend asks us
to recount it in detail, we do manage to relate a coherent
account, because we fill in the ‘gaps’ in our memory.
 Memory is an active, dynamic, complex process.

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 The scientific study of memory started only with
Ebbinghaus who wrote a volume entitled Uber das
Gadachtnis (translated as Memory in 1913, after an
extensive five year long investigation of the factors and
processes of his own memory.
 Ebbinghaus invented the nonsense syllables consisting of
a vowel between two consonants (such as QAW, XUW,
CEW etc.)
 Today Ebbinghaus is famous for his material (NSS),
method (experimental) and analysis of data (savings).
His retention curve is one of the major pioneer attempts
in psychology to reduce experimental data to a
mathematical form.

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 Memory is often viewed as a kind of store-house of
knowledge that is constantly modified by experience.
 These researchers conceptualize memory as sensory,
short term, and long-term memory (Atkinson and
Shiffrin, 1971). Alternatively those who think of memory
as a dynamic process hold that there are various levels of
processing information, and that the deeper the level at
which information is processed at the time of encoding,
the better our memory for it. They also believe that there
are no separate short-term and long-term stores (Craik
and Lockhart, 1972).

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 Tulving (1972) distinguishes between episodic and semantic
memory. Episodic memory refers to knowledge about oneself –
what did you have for breakfast, how many brothers and sisters you
are, etc. It can be usually dated as to when the information was
acquired.
 Semantic memory is the general knowledge of the world – who is
the president of United States, the importance of Ganga in the
Hindu religion, etc.
 Tulving (1972) says, “Episodic memory receives and stores
information about temporally dated episodes or events, and
temporal–spatial relations among these events…Semantic memory
is a mental thesaurus, organized knowledge a person possesses
about words and other verbal symbols, their meaning and referents,
about relations among them, and about rules, formulas, and
algorithms for the manipulation of these symbols, concepts, and
relations”.

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 Another major distinction is between explicit and implicit memory
(Schacter, 1987). Explicit memory is memory with awareness. The
subject is instructed to remember material for which he is to be
tested later on. Traditional experiments in memory that tested
recall, recognition, etc. were all experiments in explicit learning.
Research in implicit memory started in earnest only in the last two
decades of the twentieth century. Implicit memory does not involve
explicit or conscious recollection of any previous experience. It is
tested by the change on various kinds of memory tasks due to prior
experiences outside the awareness of the subject or due to
something the subject had not been explicitly instructed to learn for
a future test. Though the task instructions do not make an explicit
reference to an episode in the subject’s personal history, the
performance of the subject is nevertheless influenced by such
events.

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8. Stages of Memory
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 Memory can be described in terms of three stages: acquisition,
storage, and retrieval.
 In the acquisition stage, information is encoded into memory. It was
felt initially that all experiences are encoded in the brain in the form
of a memory trace – the engramIn his book In search of an engram
Lashley (1950) mentions that removing specific parts of a rat’s brain
affected his behaviour, but did not totally eliminate specific
memories. He concluded that if at all they are stored in the brain,
memories are distributed throughout the brain. Experimenting on
rats, Hyden (1967) found noticeable changes in the amount of RNA
in the brain of trained animals and thus recognized that RNA
presumably influences cell development. Nerve cell responds by
increasing the production of several chemical molecules whenever a
wave of electrical activity sweeps the length of the nerve cell.

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 The storage stage is the warehousing of the information
acquired. Since there is often a difference in the quantity
and quality of the information that goes into the store
and later comes out of the store, researchers assume that
processing of information continues even when it is in
storage. A great deal of information may be lost through
forgetting, and a great deal may be added through
consolidation and reconstruction.
 Retrieval refers to the process of bringing information
out of memory. There are two basic methods of retrieval.
When information is present in the environment, people
retrieve it from memory through recognition. But if the
information is not present in the environment, they must
retrieve it through recall.

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 Morgan, King, Weisz, and Schopler (1986), mentioning
the stages of memory, say that “it is the encoding,
storage, and retrieval of what was learnt earlier”.
 Crider, Goethals, and Kavanaugh (1989), adhering to the
storage view of memory, hold that “memory is the ability
to store information so that it can be used at a later
time”.
 Morris (1990) holds that “memory is the process by
which material is retained”. He conceptualizes memory
as a process in line with the information processing
approach of the modern researchers in this area.
According to Baron (2001) memory is “the capacity to
retain and later retrieve information”.

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12. Sensory Memory
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 Sensory memory is the memory for all the stimuli
impinging upon the organism at any particular time.
It is the memory for all the sensations that an
organism has at any particular time
 Sperling (1960) devised the partial report method to
study sensory memory.
 only three kinds of sensory memories have been
identified and studied by the researchers. Neisser
(1967) names them iconic memory (related to
vision), echoic (related to audition), and haptic
(related to the skin senses).

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iconic memory lasts for only
about a second, whereas echoic
memory lasts for as long as 4
seconds.

14. Characteristic of Sensory Memory
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 It is very vivid – clear and detailed. Perhaps it contains
information about all the stimuli impinging on the sense
organs.
 It lasts for a very short time. Iconic memory lasts for only
about a second whereas echoic memory lasts about four
seconds.
 It is non – associative in nature. It is neither episodic nor
semantic.
 Perhaps it processes only ecologically valid stimuli.
 It may be more implicit than explicit in nature.

15. Short Term Memory
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 Short term memory is that part of the memory
structure in which information is stored temporarily.
 short-term memory is temporarily active and
conscious. It is relatively more permanent than
sensory memory, but less enduring than long term
memory.
 It is also called the working memory, because it
contains information that is currently in use by the
individual, being acted upon, and in consciousness
(Anderson, 1985; Baddeley, 1983).

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 Evidence for STM also comes from the serial
position effect, the fact that the first few items in a
serial task are recalled the best (primacy effect),
followed by the last few items (recency effect), and
the middle items are recalled the least. The graphical
representation of the relationship between a word’s
position and its recall is called the serial position
curve.

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 Atkinson and Shiffrin (1968) hold that the short term
memory, in part, consists of buffers, or memory stores, that
hold verbal or visual information. A buffer has a relatively
limited capacity, and can hold information only for a limited
time. Information enters the buffer one item at a time.
 Baddeley (1986, 1992) claims that there are at least three
components of working memory: the articulatory loop, the
visuospatial sketchpad, and the central executive. The
articulatory loop is a kind of internal speech mechanism that
functions to rehearse verbal information. The visuospatial
sketchpad functions to rehearse visual images. Both function
independently of each other. The central executive is the skill
or process that makes decisions about which other component
of working memory must be activated to accomplish a task.

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 information is retained in the STM for a very short
while. In fact the material is completely lost in about
20 – 30 seconds. Information may be retained in
STM if the subject uses maintenance rehearsal, i.e.,
repeats the cognitive activity on the information
again and again.
 the information in STM can be transferred to the
LTM through elaborative rehearsal that involves a
deeper and more thorough analysis of the
information.

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 Information is stored in STM primarily in acoustic
(sound) codes.
 Forgetting in STM occurs due to decay as well as
interference.

20. Characteristics of STM
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 It lasts for only 20-30 seconds.
 It has limited storage capacity. It can store / process only
7+2 chunks of information at any time.
 Information can be retained in STM indefinitely through
maintenance rehearsal.
 Information is encoded in STM primarily in acoustic
codes, though other codes may also be used.
 Retrieval of information from STM is through a serial,
exhaustive search process.
 Forgetting in STM in due to both decay and interference.

21. Long Term Memory
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 Information in long-term memory exists indefinitely.
There is no time limit in long-term memory.
 LTM does not appear to be limited in storage capacity
either. It has an unlimited capacity.
 Information is acquired into LTM through elaborative
rehearsal
 A major factor in encoding of information in LTM is
activation or arousal. Generally, greater the arousal level
better is the memory.
 Information in LTM is coded in at least three ways:
semantic, visual, and acoustic. Of these, maximum use is
made of semantic codes.

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 Retrieval of information from the huge warehouse
that is LTM is largely with the help of retrieval
cues. Retrieval cues prompt people to remember by
specifying the goal of memory search, and by
directing their generation and evaluation of possible
answers.

23. Characteristics of LTM
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 There is no time limit in long-term memory.
 It has an unlimited capacity.
 Information is acquired into LTM through elaborative rehearsal.
 Information in LTM is coded in at least three ways: semantic, visual,
and acoustic. Of these, maximum use is made of semantic codes.
 The information in LTM is stored in an organized manner.
 The retrieval of information from LTM depends on retrieval cues
and has to be through a parallel, self-terminating search process.
 Forgetting occurs due to interference – proactive as well as
retroactive. Interference increases due to similarity of the two tasks,
greater amount of learning, etc.

24. Short Term Memory Long Term Memory
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 It lasts for only 20-30 seconds.
 It has limited storage capacity. It
can store / process only 7+2
chunks of information at any time.
 Information can be retained in STM
indefinitely through maintenance
rehearsal.
 Information is encoded in STM
primarily in acoustic codes, though
other codes may also be used.
 Little need for organizing
information, because it is not a
permanent store.
 Retrieval of information from STM
is through a serial, exhaustive
search process.
 Forgetting in STM in due to both
decay and interference. It lasts for
only 20-30 seconds.
• There is no time limit in long-term
memory.
• It has an unlimited capacity.
 Information is acquired into LTM
through elaborative rehearsal.
• Information in LTM is coded in at least
three ways: semantic, visual, and
acoustic. Of these, maximum use is
made of semantic codes.
• The information in LTM is stored in an
organized manner.
• The retrieval of information from LTM
depends on retrieval cues and has to
be through a parallel, self-terminating
search process.
• Forgetting occurs due to interference –
proactive as well as retroactive.
Interference increases due to similarity
of the two tasks, greater amount of
learning, etc.
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STM vs LTM

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26. Forgetting
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 Forgetting is the obverse of remembering – a failure
to retain what has been acquired.
 Retention refers to the amount of original learning
that is still effective, while forgetting refers to the
amount lost.

27. Forgetting Curve
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28. DECAY THEORY
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 Decay is a major theory of forgetting. These theorists assume that
lapse of time is responsible for forgetting. According to this view,
the memory trace deteriorates unless it is used, possibly as a result
of the continuous metabolic action of the cells of the nervous
system.
 the Decay theory holds that a physical memory trace gradually fades
as time passes. Like a message drawn in sand and the beach, a
physical memory first fades and then disappears altogether.
 Forgetting in sensory memory is largely due to decay. The icon
disappears within a second, and echoic memory lasts about 4
seconds. Since meaning is not processed, there can be no
interference.
 Forgetting in STM occurs due to decay as well as interference.

29. INTERFERENCE THEORY
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 Interference theory holds that people forget
information because one memory prevents another
from being recovered.
 Forgetting in STM as well as LTM occurs mainly due
to interference – proactive as well as retroactive (also
called proactive and retroactive inhibition).

30. Proactive Interference Vs Retroactive
Interference
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 Old learning can interfere with the memory of new
learning (proactive interference)
 New learning can interfere with the memory of old
learning (retroactive interference).
 Proactive inhibition occurs when information is
forgotten because of interference from material that
was presented before the learning of the learning
task.
 Retroactive inhibition occurs when information is
forgotten as a result of interference from material
that was presented after the learning task.

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