Human MemoryClass 11 Psychology Notes

Introduction to Human Memory

Memory is a fascinating and complex human ability that allows us to store and recall information. It's central to our identity, relationships, and daily problem-solving. Think about it: without memory, you wouldn't know who you are, recognize your friends, or even know how to solve a simple math problem.

Psychological research on memory began over a century ago with the work of Hermann Ebbinghaus, a German psychologist. In 1885, he conducted experiments on himself and discovered that we don't forget things at a steady rate. Instead, forgetting is rapid at first and then slows down over time.

Nature of Memory

Memory is the process of retaining and recalling information over a period of time. This process can be broken down into three distinct, interrelated stages. A failure at any of these stages can lead to memory loss.

• Encoding: This is the first stage, where information is recorded and registered for the first time. When our senses receive a stimulus (like seeing a word or hearing a sound), it's converted into neural impulses that our brain can process and understand. Encoding gives meaning to incoming information.
• Storage: This is the second stage, where the encoded information is retained and held over time. If information isn't stored properly, it can't be used later.
• Retrieval: This is the third stage, which involves bringing stored information back into our awareness. We retrieve memories to perform cognitive tasks like solving problems or making decisions.

1. Encoding: You hear the name, see the person's face, and register this information.
2. Storage: Your brain holds onto the name "Alex" and connects it to the memory of the face.
3. Retrieval: The next time you see the person, you bring the name "Alex" from your memory to your conscious awareness.

Information Processing Approach: The Stage Model

Early on, memory was thought of as a simple storehouse. However, with the rise of computers, psychologists began to see human memory as an information processing system, much like a computer. Both systems register, store, and manipulate information.

This comparison led to the first major model of memory, the Stage Model, proposed by Atkinson and Shiffrin in 1968. This model suggests that information passes through three distinct stages or systems.

Memory Systems: Sensory, Short-term and Long-term Memories

According to the Stage Model, there are three memory systems, each with different features and functions.

Sensory Memory

This is the very first stop for all incoming information from our senses.

• Capacity: Very large. It can take in a huge amount of sensory information.
• Duration: Extremely short, lasting less than a second.
• Function: It holds an exact replica of the stimulus for a brief moment. This is why you can sometimes see a trail of light after a bulb is switched off (iconic memory, or visual sensory memory) or hear a sound's echo for a moment after it stops (echoic memory, or auditory sensory memory).

Short-term Memory (STM)

Information that we pay attention to in our sensory memory moves to the next stage, the short-term memory (STM).

• Capacity: Small. It can hold a limited amount of information, typically around 7 items (plus or minus two).
• Duration: Brief, usually 30 seconds or less.
• Encoding: Information is primarily encoded acoustically (in terms of sound). To keep information in STM, it must be continuously rehearsed.

Long-term Memory (LTM)

Information that survives the limitations of STM moves into long-term memory (LTM).

• Capacity: Vast and practically unlimited.
• Duration: Potentially permanent. It can store information for a lifetime, from what you ate yesterday to memories from early childhood.
• Encoding: Information is encoded semantically (in terms of its meaning). Once information is in LTM, it is believed to be stored permanently. Forgetting is often seen as a retrieval failure—the memory is there, but you can't access it.

How Information Moves Between Memory Stores

Atkinson and Shiffrin proposed that control processes monitor and direct the flow of information between these memory stores.

• Selective Attention: This is the first control process. We are constantly bombarded with sensory information, but we only pay attention to a small fraction of it. Only the information that is attended to moves from sensory memory to STM.
• Maintenance Rehearsal: This process keeps information in STM. It involves simple repetition, like repeating a phone number to yourself until you can dial it. When the repetition stops, the information is lost.
• Chunking: This is another control process in STM that helps expand its limited capacity. Chunking involves grouping smaller units into larger, meaningful chunks.

• Elaborative Rehearsals: This process moves information from STM to LTM. Unlike simple repetition, elaborative rehearsal involves connecting new information to existing knowledge in your LTM. You analyze the new information, create associations, form mental images, and organize it in a logical way. The more connections you make, the more likely it is to be stored permanently.

Working Memory

More recent views suggest that Short-Term Memory is not just a passive storage box. In 1986, psychologist Baddeley proposed the concept of working memory, describing it as an active "work bench" where information is constantly handled, manipulated, and transformed.

The working memory has several components:

• Phonological Loop: Holds a limited number of sounds (acoustic information), which decay within two seconds unless rehearsed.
• Visuospatial Sketchpad: Stores a limited amount of visual and spatial information.
• Central Executive: This is the manager of the system. It organizes information from the phonological loop, visuospatial sketchpad, and LTM. It allocates attention, plans, and controls behavior.

Levels of Processing

Proposed by Craik and Lockhart in 1972, this model offers an alternative to the Stage Model. It suggests that how deeply we process information determines how well we remember it. There are three levels of processing:

1. Shallowest Level (Structural): Processing information based on its physical features. For example, noticing that the word 'CAT' is written in capital letters. This leads to fragile memory that decays quickly.
2. Intermediate Level (Phonetic): Processing information based on its sound. For example, recognizing that the word 'grew' rhymes with 'crew'. This also leads to a memory that is likely to be forgotten.
3. Deepest Level (Semantic): Processing information based on its meaning. For example, thinking about a 'cat' as a four-legged mammal with fur and connecting it to your own experiences with cats. This semantic encoding leads to a much more durable and long-lasting memory.

Types of Long-term Memory

Long-term memory is not a single, unitary system. It is made up of different types of memories.

Declarative and Procedural Memory

A major distinction within LTM is between what you can say and what you can do.

• Declarative Memory: This includes all memories of facts, names, and dates. It's the "knowing what." This information can be described verbally.
  • Examples: Knowing that India became independent on August 15, 1947, or that a frog is an amphibian.
• Procedural Memory: This refers to memories of skills and procedures for accomplishing tasks. It's the "knowing how." This information is difficult to describe in words.
  • Examples: Knowing how to ride a bicycle, make tea, or play basketball. You can do it, but it's hard to explain the exact steps verbally.

Episodic and Semantic Memory

Psychologist Tulving proposed that declarative memory can be further divided into two types:

• Episodic Memory: This contains biographical details of our personal lives. These are memories of events and experiences tied to a specific time and place. They are often emotional in nature.
  • Examples: Remembering how you felt when you stood first in your class or what your friend said during an argument.
• Semantic Memory: This is the memory of general knowledge and awareness. It stores concepts, ideas, and facts about the world. This type of memory is not tied to a specific time or place and is generally not emotional.
  • Examples: Knowing that the STD code for New Delhi is 011, that 2+6=8, or the meaning of the word 'non-violence'.

Other Classifications of Long-term Memory

• Flashbulb Memories: These are highly detailed, vivid memories of surprising or emotionally arousing events. They feel like a photograph frozen in memory, tied to a specific place, date, and time.
• Autobiographical Memory: These are personal memories from one's own life. Interestingly, most people have very few memories from the first 4-5 years of life, a phenomenon called childhood amnesia.
• Implicit Memory: This is a type of memory that a person is not consciously aware of. It is retrieved automatically and influences our behavior without our knowledge.
  • [!example] Many typists know the layout of a keyboard implicitly. They can type quickly without looking, but they may struggle to correctly label all the keys on a blank drawing of a keyboard. Their fingers "know" where the keys are, even if their conscious mind can't recall it.

Nature and Causes of Forgetting

Forgetting is a common experience. Psychologists have proposed several theories to explain why it happens.

As Hermann Ebbinghaus first showed with his curve of forgetting, the rate of forgetting is fastest soon after learning, then it slows down and stabilizes.

Forgetting due to Trace Decay

Also called the disuse theory, this is the earliest theory of forgetting. It suggests that when we form a memory, it creates a physical change in the brain called a memory trace. If these traces are not used for a long time, they simply fade away and become unavailable.

Forgetting due to Interference

This influential theory suggests that forgetting occurs because different memories stored in LTM interfere with each other, especially at the time of retrieval. There are two main types of interference:

• Proactive Interference: This is when past learning interferes with the recall of new information. (Pro = forward-moving).
  • Example: If you know English well, you might find it difficult to learn French because your knowledge of English grammar and vocabulary keeps getting in the way.
• Retroactive Interference: This is when new learning interferes with the recall of old information. (Retro = backward-moving).
  • Example: After you start learning French, you might find it difficult to recall the English equivalents of the French words you are memorizing.

Forgetting due to Retrieval Failure

Sometimes, information is stored in LTM but we are unable to access it. This type of forgetting is caused by the absence of appropriate retrieval cues—aids that help us recover stored information.

Repressed Memories

Sigmund Freud suggested that some emotionally traumatic or painful experiences are repressed, or pushed into our unconscious mind. These memories are not available for conscious retrieval because they are too threatening or embarrassing. In extreme cases, this can lead to:

• Psychological Amnesia: A person may be unable to cope with a traumatic event and mentally "flee" from it, resulting in memory loss.
• Fugue State: A severe form of amnesia where a person may forget their past, assume a new identity, and have no memory of their previous life.

Enhancing Memory

We can use various strategies, known as mnemonics, to improve our memory. These techniques help organize information, making it easier to encode and retrieve.

Mnemonics using Images

These techniques involve creating vivid mental images.

• The Keyword Method: This is useful for learning foreign languages. You link a new foreign word to an English keyword that sounds similar, and then create an interacting image of the two.
  • Example: To remember the Spanish word for duck, 'Pato', you could use the keyword 'pot' and imagine a duck swimming in a pot full of water.
• The Method of Loci: This is helpful for remembering items in a specific order. You visualize a familiar physical space (like your house) and mentally "place" the items you want to remember in different locations along a route. To recall the items, you take a mental walk along that route.

Mnemonics using Organisation

These techniques involve imposing an order on the material you want to remember.

• Chunking: As mentioned earlier, this involves combining several smaller units into larger, meaningful chunks. This is a powerful way to overcome the capacity limits of STM and improve memory.
• First Letter Technique: This involves using the first letter of each word you want to remember to form an acronym or a sentence.
  • Example: The colours of the rainbow are remembered using the acronym VIBGYOR (Violet, Indigo, Blue, Green, Yellow, Orange, Red).

A Comprehensive Approach to Memory Improvement

Beyond simple mnemonics, applying knowledge of memory processes can lead to significant improvement.

• Engage in Deep Level Processing: Always try to understand the meaning of the material you are learning. Ask questions, connect it to your own life and existing knowledge. This semantic processing creates stronger, more lasting memories.
• Minimise Interference: Avoid studying very similar subjects one after the other. Distribute your study sessions with breaks in between to reduce interference.
• Use Retrieval Cues: While learning, identify potential cues and link them to the material. These cues will help you access the information later.
• Use the PQRST Method: This strategy, developed by Thomas and Robinson, provides a structured way to study and remember material.
  1. P (Preview): Skim the chapter to get a general idea of its contents.
  2. Q (Question): Formulate questions based on the chapter headings.
  3. R (Read): Read the chapter carefully, looking for answers to your questions.
  4. S (Self-recitation): Try to recall and rewrite the information you have read.
  5. T (Test): Test yourself to see how much you have understood and retained.