Human Memory Class 11 Psychology Notes


  • 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.
  • Memory is conceptualised as a process consisting of three independent, though interrelated stages.
  • These are encoding, storage, and retrieval. Any information received by us necessarily goes through these stages


  • 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
  • In encoding, incoming information is received and some meaning is derived.


  • 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


  • Retrieval is the third stage of 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.
  • 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.


  • 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.
  • 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
  • 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.
  • 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.


According to the Stage Model, there are three memory systems : the Sensory Memory, the Short-term Memory and the Long-term Memory.

Sensory Memory

  • The definition of sensory memory is the ability to retain impressions of sensory information after the original stimulus has ceased.
  • The incoming information first enters the sensory memory.
  • It refers to items detected by the sensory receptors which are retained temporarily in the sensory registers and which have a large capacity for unprocessed information but are only able to hold accurate images of sensory information momentarily.
  • 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 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

  • short term memory is the capacity for holding a small amount of information in mind in an active, readily available state for a short 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.
  • Short-term memory acts as a scratch-pad for temporary recall of the information under  process.
  • For instance, in order to understand this sentence you need to hold in your mind the beginning of the sentence you read the rest
  • STM is fragile but not as fragile as sensory registers where the information decays automatically in less than a second.

Long-term Memory

  • long term memory is memory that can last as little as a few days or as long as decades.
  • It differs structurally and functionally from working memory or short-term memory.
  • It is a permanent storehouse of all information
  • 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 retrievethe stored information.

control processes

  • Atkinson and Shiffrin propose the notion of control processes which function to monitor the flow of information through various memory stores.
  • information which is attended to enters the STM from sensory registers and in that sense, selective attention
  • the first control process that decides what will travel from sensory registers to STM.
  • Sense impressions, which do not receive attention, fade away quickly.

maintenance rehearsal

  • The STM then sets into motion another control process of maintenance rehearsal to retain the information for as much time as required.
  • rehearsals simply maintain information through  repetition and when such repetitions discontinue the information is lost.


  • control process, which operates in STM to expand its capacity, is Chunking
  • chunking it is possible to expand the capacity of STM
  • For creating chunks its is important to discover some organisation principals which can link similasr units.
  • Chunking can also be used as to increass the memory.

elaborative rehearsals

  • From the STM information enters the longterm 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.
  • 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
  • Experiments, which were carried out to test the stage model of memory, have produced mixed results
  • Shallice and Warrington in the year 1970 had cited the case of a man known as KF who met with an accident and damaged a portion of the left side of his cerebral hemisphere.
  • The stage model suggests that informations are committed to the long-term memory via STM and if KF’s STM was affected
  • memory processes are similar irrespective of whether any information is retained for a few seconds or for many years and that memory can be adequately understood without positing separate memory stores


  • The levels of processing view was proposed by Craik and Lockhart in 197 2
  • This view suggests that the processing of any new information relates to the manner in which it is perceived, analysed, and understood which in turn determines the extent to which it will eventually be retained
  •  Craik and Lockhart proposed that it is possible to analyse the incoming information at more than one level. One may analyse it in terms of its physical or structural features.
  • At an intermediate level one might consider and attend to the phonetic sounds that are attached to the letters and therefore the structural features are transformed into at least one meaningful word say, a word cat that has three specific letters.
  • to ensure that the information is retained for a longer period, it is important that it gets analysed and understood in terms of its meaning.
  • analysing information in terms of its structural and phonetic features amounts to shallower processing while encoding it in terms of the meaning it carries is the deepest processing level that leads to memory that resists forgetting considerably.
  • Understanding memory as an outcome of the manner in which information is encoded initially has an important implication for learning.
  • learning a new lesson, you must focus on elaborating the meaning of its contents in as much detail as possible and must not depend on rote memorisation.


  • long-term memory is not unitary because it contains a wide variety of information.
  • In view of this, contemporary formulations envisage longterm memory as consisting of various types.
  • All information pertaining to facts, names, dates are part of declarative memory.
  • Procedural memory  refers to memories relating to procedures for accomplishing various tasks and skills
  • Facts retained in the declarative memory are amenable to verbal descriptions while contents of procedural memory cannot be described easily.
  • Episodic memory contains biographical details of our lives.
  • Memories relating to our personal life experiences constitute the episodic memory and it is for this reason that its contents are generally emotional in nature.
  • there are painful and unpleasant experiences which are not remembered in as much detail as pleasant life experiences.
  • Semantic memory is the memory of general awareness and knowledge.
  • All concepts, ideas and rules of logic are stored in semantic memory
  • Unlike episodic memory this kind of memory is not dated
  • the contents of semantic memory relate to facts and ideas of general awareness and knowledge, it is affect-neutral and not susceptible to forgetting.


  • long-term memory holds a very large amount of information which is put to use with amazing efficiency, it would be very useful to know how our memory system organises its contents so that the right information is available at the right moment.
  • It is important to note at this point that many ideas relating to organisation of the content of long-term memory have resulted from experiments that have employed semantic retrieval tasks.
  • Concepts are mental categories for objects and events, which are similar to each other in one or in more than one way.
  • Concepts once formed get organised in categories — a category itself is a concept but it also functions to organise similarities among other concepts based on common features
  • Concepts may also get organised in schema.
  • They are mental frameworks which represent our knowledge and assumptions about the world
  • In the year 1969, Allan Collins and Ross Quillian published a landmark research paper in which they suggested that knowledge in long-term memory is organised hierarchically and assumes a network structure.
  • Elements of this structure are called nodes.
  • Nodes are  concepts while connections between nodes are labelled relationships, which indicate category membership or concept attributes.
  • as the predicate became hierarchically more remote from the subject in a sentence, participants took longer time to verify that it is true or false.
  • we store all knowledge at a certain level that ‘applies to all the members of a category without having to repeat that information at the lower levels in the hierarchy’.
  • This ensures a high degree of cognitive economy, which means maximum and efficient use of the capacity of
    long-term memory with minimum redundancy.
  • It has been shown that information can be coded in a perceptual format or in terms of images.
  • An image is a concrete form of representation which directly conveys the perceptual attributes of an object.
  • images and the knowledge related to them is encoded both verbally as well as visually. This is known as dual coding hypothesis, originally proposed by Paivio.
  • According to this hypothesis, concrete nouns and information related to concrete objects are encoded and stored in the form of images while information related to abstract concepts assume a verbal and a descriptive code.
  • any information which has been encoded verbally as well as in the form of images is recalled with greater ease.
  • Information which has been encoded and stored in the form of images leads to the development of mental models.
  • Mental models refer to our belief about the manner in which our environment is structured and such beliefs are formed with the help of concrete images as well as verbal descriptions


  • Ebbinghaus and his followers who emphasised that the  quantity of information that can be stored in the memory and judged its accuracy by matching the contents of storage and reproduction.
  • If the reproduced version of the stored material showed any deviation, it was seen as an error and a case of memory failure.
  • This storage metaphor of memory implied that the memory was a passive occurrence of learnt material that has been transported to its long-term storehouse.
  • This was challenged by Bartlett who contended that memory is an active process and all that we have stored undergoes continuous change and modification.
  • What we memorise is influenced by the meaning we assign to the stimulus material and once it is committed to  our memory system, it cannot remain in isolation from other cognitive processes.
  • Bartlett saw memory as a constructive and not a reproductive process.
  • Bartlett to understand the manner in which content of any specific memory gets affected by a person’s knowledge, goals, motivation, preferences and various other psychological processes.
  • Bartlett used the method of serial reproduction in which the participants of his experiments recalled the memory materials repeatedly at varying time intervals.
  • While engaging in serial reproduction of learned material his participants committed a wide variety of ‘errors’  which Bartlett considered useful in understanding the process of memory construction.
  • Schemas refer to an organisation of past experiences and knowledge, which influence the way in which incoming information is interpreted, stored, and later retrieved.
  • Memory becomes an active process of construction where information is encoded and stored in terms of a person’s understanding and within her/his previous knowledge and expectations.


  • Each one of us has experienced forgetting and its consequences almost routinely
  • The first systematic attempt to understand the nature of forgetting was made by Hermann Ebbinghaus, who memorised lists of nonsense syllables and then measured the number of trials he took to relearn the same list at varying time intervals.
  • the rate of forgetting is maximum in the first nine hours, particularly during the first hour.
  • After that the rate slows down and not much is forgotten even after many days.
  • Ebbinghaus’s experiments constituted initial explorations and were not very sophisticated yet they have
    influenced memory research in many important ways.
  • there is always a sharp drop in memory and thereafter the decline is very gradual

Forgetting due to Trace Decay

  • Trace decay (also called disuse theory) is the earliest theory of forgetting.
  • memory leads to modification in the central nervous system, which is akin to physical changes in the brain called memory traces.
  • When these memory traces are not used for a long time, they simply fade away and become unavailable.
  • This theory has been proved inadequate on several grounds.
  • If forgetting takes place because memory traces decay due to disuse,
  • people who go to sleep after memorising should forget more compared to those who remain awake, simply because there is no way in which memory traces can be put to use during sleep.
  • Results,  show just the opposite. Those who remain awake after memorising (waking condition) show greater forgetting than those who sleep (sleeping condition).
  • Because trace decay theory did not explain forgetting adequately

Forgetting due to Interference

  • the interference theory which suggests that forgetting is due to interference between various informations that the memory store contains.
  • This theory assumes that learning and memorising involve forming of associations between items and once acquired, these associations remain intact in the memory.
  • interference comes about at a time of retrieval when these various sets of associations compete with each other for retrieval.
  • Interference can be proactive (forward moving) which means what you have learnt earlier interferes with the recall of your subsequent learning or retroactive (backward moving) which refers to difficulty in recalling what you have learnt earlier because of learning a new material.
  • in proactive interference, past learning interferes with the recall of later learning while in retroactive interference the later learning interferes with the recall of past learning.

Forgetting due to Retrieval Failure

  • Forgetting can occur not only because the memory traces have decayed over time or because independent sets of stored associations compete at the time of recall but also because at the time of recall, either the retrieval cues are absent or they are inappropriate.
  • Retrieval cues are aids which help us in recovering information stored in the memory.
  • Tulving and his associates carried out several experiments to show that contents of memory may become inaccessible either due to absence or inappropriateness of retrieval cues that are available/employed at the time of recall.


Mnemonics using Images

  • Mnemonics using images require that you create vivid and interacting images of and around the material you wish to remember.
  • The two prominent mnemonic devices, which make interesting use of images, are the keyword method and the method of loci.

The Keyword Method

  • Suppose you want to learn words of any foreign language.
  • In keyword method, an English word (the assumption here is that you know English language) that sounds similar to the word of a foreign language is identified.
  • This English word will function as the keyword.
  • This method of learning words of a foreign language is much superior compared to any kind of rote memorisation.

The Method of Loci

  • In order to use the method of loci, items you want to remember are placed as objects arranged in a physical
    space in the form of visual images.
  • This method is particularly helpful in remembering items in a serial order.
  • It requires that you first visualise objects/places that you know well in a specific sequence, imagine the objects
    you want to remember and associate them one by one to the physical locations

Mnemonics using Organisation

  • Organisation refers to imposing certain order on the material you want to remember.
  • Mnemonics of this kind are helpful because the framework you create while organisation makes the retrieval task fairly easy.


  • chunking can increase the capacity of short-term memory.
  • several smaller units are combined to form large chunks.
  • For creating chunks, it is important to discover some organisation principles, which can link smaller units.
  • Therefore, apart from being a control mechanism to increase the capacity of short-term memory, chunking can be used to improve memory as well.

First Letter Technique

  • In order to employ the first letter technique, you need to pick up the first letter of each word you want to
    remember and arrange them to form another word or a sentence


  • Mnemonic strategies for memory enhancement are too simplistic and perhaps underestimate complexities of memory tasks and difficulties people experience while memorising.
  • In place of mnemonics, a more comprehensive approach to memory improvement has been suggested by many

 Engage in Deep Level Processing

  •  If you want to memorise any information well, engage in deep level processing.
  • Craik and Lockhart have demonstrated that processing information in terms of meaning that they convey leads to better memory as compared to attending to their surface features.
  • Deep processing would involve asking as many questions related to the information as possible, considering its meaning and examining its relationships to the facts you already know.
  • the new information will become a part of your existing knowledge framework and the chances that it will be
    remembered are increased.

Minimise Interference

  •  Interference, is a major cause of forgetting and therefore you should try to avoid it as much as possible.
  • that maximum interference is caused when very similar materials are learned in a sequence
  • Arrange your study in such a way that you do not learn similar subjects one after the other.
  • Instead, pick up some other subject unrelated to the previous one.
  • If that is not possible, distribute your learning/practice.
  • This means giving yourself intermittent rest periods while studying to minimise interferenc

 Give Yourself enough Retrieval Cues

  •  Cues will be easier to remember compared to the entire content and the links you have created between cues and the content will facilitate the retrieval process.
  • Thomas and Robinson have developed another strategy to help students in remembering more which they called the methods of PQRST.
  • This acronym stands for Preview, Question, Read, Self-recitation, and Test.
  • Preview refers to giving a cursory look at the chapter and familiarising oneself with its contents.
  • Question means raising questions and seeking answers from the lesson.
  • start reading and look for answers of questions you had raised.
  • After reading try to rewrite what you have read and at the end test how much you have been able to understand.
  • At the end, a note of caution must be sounded.
  • There is no one method that can solve all problems related to retention and bring about an overnight memory
  • In order to improve your memory, you need to attend to a wide variety of factors which affect your memory such as your health status, your interest and motivation, your familiarity with the subject matter and so on.
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  1. The notes were really helpful ..The day before my exam ..These notes gave me rejuvenation ..Thank you so much …!

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