| Latest Psychology NCERT Notes, Solutions and Extra Q & A (Class 11th & 12th) | |||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 11th | 12th | ||||||||||||||||||
Chapter 6 Human Memory
Introduction
Memory is a fundamental human ability that allows us to retain and retrieve information over time. It plays a vital role in maintaining our sense of self, managing relationships, and performing cognitive tasks like problem-solving and decision-making.
Psychological research on memory has a history spanning over a century, with early systematic studies conducted by Hermann Ebbinghaus in the late 19th century. His work on memorising nonsense syllables revealed that forgetting occurs rapidly initially but then stabilises over time.
Psychologists investigate how information is encoded, stored, and retrieved from memory, why forgetting happens, and how memory can be improved. This chapter explores various aspects of memory, different models explaining its mechanisms, causes of forgetting, and techniques for enhancing memory performance.
Nature of Memory
Memory is defined as the capacity to hold onto and subsequently recall information. This process varies depending on the task, from retaining data for a few seconds (like a phone number) to remembering skills or facts learned years ago (like arithmetic). Memory is understood as a cognitive process involving a sequence of stages: encoding, storage, and retrieval.
All information we encounter undergoes these stages:
- Encoding: The initial stage where information is registered and recorded in a usable form for the memory system. Incoming stimuli generate neural impulses that are processed by the brain, and meaning is derived, allowing the information to be represented for further processing.
- Storage: The second stage, where encoded information is retained or held onto over a period of time so it can be accessed later.
- Retrieval: The third stage, where stored information is brought back into conscious awareness for use in various tasks like thinking, problem-solving, or making decisions.
Failure in memory (forgetting) can occur at any of these stages. Information might not be recalled because it was not encoded correctly, stored weakly, or could not be accessed or retrieved when needed.
Information Processing Approach : The Stage Model
Inspired by the workings of computers, the Information Processing Approach views human memory as a system that processes information sequentially. The first prominent model, the Stage Model, proposed by Atkinson and Shiffrin (1968), suggests that memory consists of three distinct, interconnected systems or stores through which information flows.
(This model illustrates information entering Sensory Memory, then potentially transferring to Short-term Memory, and finally to Long-term Memory, with control processes like attention and rehearsal influencing the flow.)
Memory Systems : Sensory, Short-term and Long-term Memories
According to the Stage Model, the three memory systems are:
- Sensory Memory: The initial point of entry for incoming information from the senses. It has a very large capacity but retains information for an extremely short duration (less than a second). It registers stimuli from each sense modality as a near-exact replica. Visual sensory memory is called iconic memory (e.g., visual after-images), and auditory sensory memory is called echoic memory (e.g., lingering sound reverberations).
- Short-term Memory (STM): Information that is attended to from sensory memory enters STM. It has a small capacity (typically holds about 7 ± 2 items) and retains information for a brief period (around 30 seconds or less). Information in STM is primarily encoded acoustically (based on sound). Without active maintenance (rehearsal), information quickly decays from STM. STM is fragile but lasts longer than sensory memory.
- Long-term Memory (LTM): Information that survives the limitations of STM enters LTM. It is considered a permanent storehouse with a vast, essentially unlimited capacity. Information in LTM is primarily encoded semantically (based on meaning). Forgetting from LTM is often seen as retrieval failure rather than complete loss of information.
The flow of information between these stores is governed by control processes, which monitor and regulate the movement of information. Selective attention is the first control process, determining what information moves from sensory memory to STM. Once in STM, maintenance rehearsal (simple repetition) is a control process used to keep information active. Chunking is another STM control process that increases its apparent capacity by grouping smaller units into larger meaningful ones (e.g., remembering digits as dates). Elaborative rehearsal is the control process that moves information from STM to LTM. Unlike simple repetition, it involves connecting new information with existing knowledge in LTM through analysis, association, and organisation, facilitating long-term retention.
Experimental tests of the Stage Model have yielded mixed results. While some evidence supports the idea of separate STM and LTM stores, others question their distinctiveness, showing semantic encoding in STM and acoustic encoding in LTM are possible, and that memory processes might be similar regardless of retention duration. Studies of brain-injured patients (like KF, whose LTM was intact despite affected STM) have also challenged the model's idea that information must pass through STM to reach LTM, leading to alternative memory conceptualisations.
Working Memory (Box 6.1)
More recent psychological views propose that short-term memory is not a single entity but a dynamic system with multiple components, known as working memory. Developed by Baddeley (1986), this model sees STM as a mental workspace where information is actively handled, manipulated, and transformed during various cognitive tasks.
Working memory consists of several components:
- Phonological loop: Holds a limited amount of auditory information (sounds). Unless rehearsed, sounds decay within approximately 2 seconds.
- Visuospatial sketchpad: Stores visual and spatial information. Like the phonological loop, its capacity is limited.
- Central Executive: Acts as an executive controller. It organises and integrates information from the phonological loop, visuospatial sketchpad, and long-term memory. The Central Executive allocates attentional resources needed for cognitive operations, monitors, plans, and controls behaviour.
Levels of Processing
The Levels of Processing view, proposed by Craik and Lockhart (1972), suggests that the depth at which information is processed determines how well it will be retained. The more deeply information is processed, the better the memory.
Information can be processed at different levels:
- Shallowest Level (Structural/Physical): Processing based on physical or structural features of the stimulus, such as the shape of letters in a word or the colour of ink. Memory from this level is fragile and decays quickly.
- Intermediate Level (Phonetic): Processing based on the sounds of the stimulus, transforming structural features into meaningful sound units (e.g., processing the sounds of letters to form a word). Memory from this level is also fragile.
- Deepest Level (Semantic): Processing based on the meaning of the stimulus, understanding its significance, and connecting it to existing knowledge. This is the deepest level of processing, leading to memory that is more resistant to forgetting. Semantic encoding involves relating the information to other facts, concepts, images, or personal experiences.
This view highlights that focusing on understanding the meaning and elaborating on new information (semantic processing) is crucial for long-term retention, advocating against rote memorisation.
Types of Long-term Memory
Similar to the multicomponent view of short-term memory, long-term memory is also considered non-unitary, containing various types of information. Contemporary theories classify LTM into different categories.
Declarative and Procedural; Episodic and Semantic
One major classification divides LTM into:
- Declarative Memory: Stores factual information, names, dates, events, concepts, etc. It contains knowledge that can be verbally stated or declared (e.g., "A rickshaw has three wheels," "India's independence date").
- Procedural Memory (Nondeclarative Memory): Stores information about procedures, skills, and how to perform tasks (e.g., how to ride a bicycle, make tea, play an instrument). The contents of procedural memory are often difficult to describe verbally, even if the skill is well-learned.
Tulving further classified Declarative Memory into two types:
- Episodic Memory: Stores biographical details and personal life experiences. These memories are often emotionally charged and tied to specific times and places (e.g., remembering how you felt winning a competition, a friend's reaction to a broken promise). While vivid, not all life events are remembered, and painful experiences might be less detailed than pleasant ones.
- Semantic Memory: Stores general knowledge, concepts, ideas, rules, and facts about the world that are not tied to specific personal experiences. This memory is affect-neutral and generally highly resistant to forgetting (e.g., meaning of 'non-violence', mathematical facts, capital cities).
See Box 6.2 for other classifications of long-term memory phenomena.
Long-term Memory Classification (Box 6.2)
Beyond the primary classifications, researchers have identified other interesting phenomena related to long-term memory:
- Flashbulb Memories: These are exceptionally vivid, detailed, and long-lasting memories of emotionally arousing or surprising public events (e.g., remembering exactly where you were and what you were doing when you heard about a major historical event). They are like mental photographs, often tied to specific times and places, possibly due to deeper processing and multiple retrieval cues.
- Autobiographical Memory: Refers to personal memories across one's life. Memories are not evenly distributed; there's typically a period of childhood amnesia (very few memories from the first 4-5 years). Memory frequency increases dramatically in early adulthood (twenties), possibly due to the novelty and significance of events during this period. In old age, recent events are often better remembered.
- Implicit Memory: Refers to memories that influence behaviour without conscious awareness. Individuals are not consciously aware that they possess these memories. A classic example is procedural knowledge (like typing skills) which may be difficult to verbalise consciously. Implicit memories are retrieved automatically and can be demonstrated even in individuals with explicit memory impairments (e.g., brain-injured patients who can complete word fragments of previously seen words without conscious recall).
Methods of Memory Measurement (Box 6.3)
Various methods are used to measure memory, depending on the type of memory being studied:
| Method | Type of Memory Measured | Description |
|---|---|---|
| Free Recall | Facts/Episodes (Declarative, Episodic/Semantic) | Participants memorise a list of items and recall them in any order after a time interval. Higher recall indicates better memory. |
| Recognition | Facts/Episodes (Declarative, Episodic/Semantic) | Participants see items they memorised presented alongside new distracter items and must identify the memorised items. Higher recognition of old items indicates better memory. |
| Sentence Verification Task | Semantic Memory | Participants judge whether sentences stating factual information are true or false. Faster response times indicate better access to the semantic knowledge needed for verification. |
| Priming | Implicit Memory / Non-verbal Information | Participants are exposed to stimuli (e.g., words) and later show facilitated processing (e.g., completing word fragments faster) of those stimuli compared to new ones, even without conscious awareness of remembering the initial exposure. Measures memory that cannot be verbally reported. |
Nature and Causes of Forgetting
Forgetting is the inability to retrieve information that was previously learned or stored in memory. It is a common experience, leading to questions about why it occurs and what causes it.
Hermann Ebbinghaus's pioneering studies using nonsense syllables revealed a characteristic pattern of forgetting: a rapid decline in memory initially, followed by a much slower, more stable rate of forgetting over time (Fig.6.2).
(A graph illustrating Ebbinghaus's forgetting curve, showing the percentage of information retained or forgotten over various time intervals after learning, typically showing a steep drop initially and then levelling off.)
Several theories attempt to explain forgetting:
Forgetting due to Trace Decay, Interference and Retrieval Failure
- Trace Decay Theory (Disuse Theory): An early theory assuming that learning creates physical or chemical changes in the brain called memory traces. Forgetting occurs because these traces naturally fade away or decay over time if they are not used. However, this theory is inadequate; studies show that forgetting is less during sleep (when traces are unused) than during waking hours, suggesting disuse alone isn't the primary cause.
- Interference Theory: A more influential theory suggesting that forgetting occurs due to interference between different pieces of information stored in memory. Learning involves forming associations. Interference happens during retrieval when competing associations make it difficult to access the desired information. There are two types:
- Proactive Interference: Earlier learning interferes with the recall of subsequent learning (forward moving).
- Retroactive Interference: Later learning interferes with the recall of earlier learning (backward moving).
- Retrieval Failure Theory: This theory suggests that forgetting is not due to the decay of memory traces or interference from competing memories, but because the necessary cues for retrieving the information are either absent or inappropriate at the time of recall. Retrieval cues are aids that help access stored information. Tulving's research supports this, showing that providing relevant cues (like category names for a list of words) can significantly improve recall of seemingly inaccessible information. The physical context of learning can also serve as an effective retrieval cue.
| Interference Type | Phase 1 | Phase 2 | Testing Phase |
|---|---|---|---|
| Retroactive Interference | Experimental Group: Learns A Control Group: Learns A |
Experimental Group: Learns B Control Group: Rests |
Experimental Group: Recalls A Control Group: Recalls A |
| Proactive Interference | Experimental Group: Learns A Control Group: Rests |
Experimental Group: Learns B Control Group: Learns B |
Experimental Group: Recalls B Control Group: Recalls B |
Repressed Memories (Box 6.4)
Traumatic or emotionally painful experiences can sometimes be difficult to recall. Sigmund Freud suggested that highly traumatic, threatening, or embarrassing experiences are pushed out of conscious awareness into the unconscious mind, a process called repression, making them unavailable for retrieval.
In some cases, extreme trauma or stress can lead to psychological amnesia or dissociative disorders like a fugue state, where individuals may lose memory of their past identity and assume a new one. Forgetfulness or memory loss under stress and high anxiety is also a common phenomenon, where individuals may forget information they know well when facing high-stakes situations like examinations.
Enhancing Memory
Improving memory is a common desire. Various strategies called mnemonics are used to enhance memory performance. Mnemonics either utilise images or emphasise organising information.
Mnemonics using Images and Organisation
Mnemonics using Images: These techniques involve creating vivid mental images of the material to be remembered.
- The Keyword Method: Useful for learning foreign language vocabulary. Involves identifying an English word (keyword) that sounds similar to the foreign word and creating an interacting image of the keyword and the foreign word's meaning (e.g., Spanish 'Pato' (duck) - keyword 'pot' - imagine a duck in a pot).
- The Method of Loci: Useful for remembering items in a serial order. Involves visualising familiar physical locations in a sequence and then mentally placing the items to be remembered at these locations through interacting images. During recall, one mentally walks through the locations, retrieving the associated items.
- Chunking: Already discussed as an STM control process, it involves combining smaller units into larger, meaningful chunks to increase memory capacity. Requires finding organisation principles to link units.
- First Letter Technique: Creating a word or sentence from the first letters of the items to be remembered (e.g., VIBGYOR for rainbow colors).
While mnemonics can be helpful, a more comprehensive approach to memory improvement suggests focusing on fundamental memory processes:
- Engage in Deep Level Processing: Process information in terms of its meaning (semantic encoding), not just physical features or sounds. Ask questions about the information, relate it to existing knowledge and personal experiences to embed it in your knowledge network.
- Minimise Interference: Avoid learning similar materials in sequence. Distribute study sessions with breaks to reduce proactive and retroactive interference.
- Give Yourself enough Retrieval Cues: Identify potential cues within the study material and link parts of the information to these cues during learning. This facilitates retrieval later, as cues are easier to remember than the entire content.
Thomas and Robinson's PQRST method is a study strategy incorporating these principles: Preview (get an overview), Question (formulate questions), Read (find answers), Self-recitation (recite what you learned), and Test (assess recall).
True memory improvement is not achieved overnight or through a single method. It requires attending to various factors like health, interest, motivation, familiarity with the subject, and consistently using appropriate memory strategies based on the task.
Key Terms
Chunking, Control process, Echoic memory, Encoding, Episodic memory, Elaborative rehearsals, Fugue state, Information processing approach, Maintenance rehearsals, Memory making, Mnemonics, Semantic memory, Serial reproduction, Working memory
Summary
Memory involves encoding, storage, and retrieval.
The Stage Model proposes three stores: Sensory (brief, large capacity), Short-term (limited capacity/duration, acoustic encoding, maintenance rehearsal, chunking), and Long-term (vast capacity, semantic encoding, permanent, elaborative rehearsal). Working memory is a multi-component STM (phonological loop, visuospatial sketchpad, central executive).
Levels of Processing view suggests depth of encoding (structural, phonetic, semantic) determines retention; deeper semantic processing is better.
LTM types: Declarative (facts, names - Episodic/Semantic) vs. Procedural (skills). Episodic is personal, dated, emotional; Semantic is general knowledge, undated, affect-neutral.
Other LTM concepts: Flashbulb (vivid, arousing events), Autobiographical (personal life, childhood amnesia, memory surge in twenties), Implicit (unconscious, influences behavior, e.g., priming).
Forgetting: Rapid initial loss, then gradual (Ebbinghaus). Theories: Trace decay (fading over time), Interference (proactive/retroactive competition), Retrieval failure (absent/inappropriate cues). Repression pushes traumatic memories to unconscious.
Memory enhancement: Mnemonics (images like keyword, method of loci; organization like chunking, first letter technique). General strategies: deep processing, minimizing interference, using retrieval cues (PQRST method).