Study Notes on Memory
Memory
Introduction to Memory
Memory is a multifaceted process that investigates several critical questions:
How do we process and store information?
Are there different types of memory?
How do we retrieve memories?
Why do we forget?
External stimuli, such as photographs, can effectively trigger memories and revive past experiences.
How Memory Functions
Memory functions as an information-processing system, drawing parallels to computers yet differing fundamentally:
The brain does not always retrieve unbiased memories.
Memory is more comprehensive than a mere storehouse; it is a dynamic set of processes used for encoding, storing, and retrieving information over various time periods.
The three foundational components of memory are:
Encoding - The process of inputting information into the memory system.
Storage - The retention of encoded information over time.
Retrieval - The act of recovering information stored in memory and bringing it back into conscious awareness.
Encoding
The brain captures information from the environment through several steps:
Labels: Identification and categorization of information.
Organization: Structuring information alongside similar data.
Connection: Linking new concepts to existing knowledge for better retention.
Encoding can occur through two primary types:
Automatic Encoding:
Involves details like time, space, frequency, and the meanings of words.
Typically occurs unconsciously and without deliberate processing.
Effortful Encoding:
Requires significant time and attention.
Involves conscious work to process information deeply.
Types of Encoding
Semantic Encoding:
Involves encoding words and their meanings.
Considered the most effective encoding method due to its depth of processing and capacity to link meanings to new information, facilitating later recall.
Visual Encoding:
Pertains to the encoding of images.
Concrete words like car and dog that evoke mental images are easier to remember compared to abstract words like honor or truth.
Acoustic Encoding:
Relates to the encoding of sounds.
The self-reference effect enhances memory retention through personal connection to the material being learned.
Storage of Memory
Baddeley-Hitch Model
The Baddeley-Hitch model posits that short-term memory (STM) comprises different systems for storing various types of information, likening storage to computer files/folders:
Three Short-Term Memory Systems:
Visuospatial Sketchpad
Episodic Buffer
Phonological Loop
The central executive oversees information flow between STM and long-term memory (LTM).
Atkinson-Shiffrin Model
According to the Atkinson-Shiffrin model, memory functions in stages to move information from short-term to long-term memory, suggesting that memory processing mirrors computer procedures.
Sensory Memory
Sensory memory is the brief storage of sensory events (sights, sounds, and tastes) for approximately 1-2 seconds. The steps include:
If not deemed significant, information is discarded.
Valuable information transitions into short-term memory.
Short-Term Memory (STM)
Short-Term Memory/Working Memory:
A temporary storage system that processes incoming sensory memory, lasting roughly 20 seconds.
Typically has a capacity of about 7 items, plus or minus 2, as established by researcher George Miller.
Short-term memories may either be discarded or consolidated into long-term memory through memory consolidation.
Rehearsal is the method of consciously repeating information to be remembered.
Long-Term Memory (LTM)
Long-term memory signifies continuous information storage with no capacity limit, functioning similarly to a computer hard drive. Two primary components of LTM are:
Explicit Memories:
Semantic Memories: Knowledge of facts, words, and concepts.
Example: Awareness that Miss Rev is the mascot of Texas A&M University.
Episodic Memories: Personal experiences/events from one’s life.
Example: Remembering when one met Miss Rev.
Implicit Memories:
Procedural Memories: Skill and action-based knowledge (e.g., riding a bike).
Emotional Conditioning: The associations between stimuli and emotional responses.
Example: Having a fear of spiders, possibly linked to previous experiences (often unconsciously oriented).
Retrieval of Memories
Retrieval is the action of accessing stored memory and reactivating it in conscious awareness. There are three major retrieval methods:
Recall: Accessing information without prompts.
Typically used in essay exams.
Recognition: Identifying previously learned information upon encounter.
Common in multiple-choice tests.
Relearning: Re-acquiring previously known information (e.g., re-learning a language).
Brain Regions Involved in Memory
Different brain regions are integrally related to various memory functions:
Prefrontal Cortex: Involved in semantic memory processes.
Amygdala: Critical for emotional memory, particularly fear responses.
Hippocampus: Vital for explicit memory consolidation and spatial memory.
Cerebellum: Plays a role in procedural memory processing, such as learning motor tasks.
Historical Insights into Memory
The early inquiry by Karl Lashley into whether there is a physical trace of memory led to his exploration for an engram, theorized to represent memories in the brain:
Lashley's experiments on rats learning mazes revealed that even with brain lesions, the rats retained their knowledge of the maze.
Results led to the Equipotentiality Hypothesis, implying that memory functions can be taken over by other parts of the brain if one area is damaged.
Additional Notes on Brain Structures
Amygdala
Responsible for regulating emotions associated with memories, particularly in the context of fear and aggression.
The amygdala enhances memory storage for emotionally charged experiences, as seen in Pavlovian conditioning studies.
Hippocampus
Critical for the formation and retrieval of explicit memories, especially recognition and context learning.
Damage can impede forming new declarative memories, as evidenced in the case study of patient H.M., whose brain surgery impacted his ability to form new semantic or episodic memories while preserving his procedural memory.
Cerebellum and Prefrontal Cortex
Cerebellum: Engaged in procedural memory processes and classical conditioning tasks, with damage preventing such conditioning from occurring.
Prefrontal Cortex (PFC): Engaged in semantic tasks, with areas of activation differing between encoding (left brain) and retrieval (right brain).
Neurotransmitters and Memory
Memory consolidation occurs due to the repeated activity of neurons, enhancing neurotransmitter concentration in synapses and thereby strengthening synaptic connections.
Key neurotransmitters involved in memory include:
Epinephrine, Dopamine, Serotonin, Glutamate, Acetylcholine.
Arousal Theory: Higher emotional arousal enhances memory formation, leading to strong emotional memories, such as flashbulb memories, which vividly recall significant emotional events.
Flashbulb Memories
A type of explicit memory characterized by exceptionally vivid recollection of highly significant emotional events, often serving as generational touchstones:
Examples include:
Assassination of JFK
Moon Landing
9/11 Attacks
COVID-19 Lockdowns.
These memories can vary based on cultural background and personal involvement, influencing how deeply they are embedded in memory.
Amnesia
Amnesia is characterized by the loss of long-term memory due to various reasons, including disease, physical trauma, or psychological factors.
Types of Amnesia
Anterograde Amnesia:
The inability to form new memories following a traumatic event, often linked to hippocampal damage.
Retrograde Amnesia:
The loss of memories before the onset of trauma, which can be partial or total.
Clive Wearing Case Study
Clive Wearing’s experience illustrates both anterograde and retrograde amnesia, showcasing the profound impact on his memory and sense of self. His condition causes him to live in a continuous present, experiencing profound gaps in memory.
Memory Construction & Reconstruction
Construction: The process of forming new memories.
Reconstruction: The retrieval process which modifies old memories, often leading to inaccuracies or alterations.
Suggestibility: Refers to how external misinformation can affect memory recall, producing false memories and implications for the reliability of eyewitness testimonies.
The Misinformation Effect
Misinformation Effect Paradigm: Demonstrates how post-event misinformation can alter a person's memory of the original experience.
Example Study (1974):
College students watched films of car accidents and were led to estimate speed based on varying question phrases (e.g., "smashed" vs. "contacted").
Those exposed to the word “smashed” estimated higher speeds and reported seeing broken glass more frequently, illustrating how suggested phrasing influenced memory recall.
Repressed and Recovered Memories
The concept of false memory syndrome indicates the phenomenon where one recalls autobiographical memories inaccurately. The notion of repressed memories, particularly from childhood trauma, is debated:
Some psychologists assert that these memories can later resurface, while others argue such recollections are influenced by suggestion rather than genuine recall.
The Process of Forgetting
Forgetting refers to the loss of information from long-term memory, which may occur due to various factors:
Encoding Failure
Occurs when information fails to be stored correctly in memory, often due to lack of attention or effort in encoding.
Memory Errors: Schacter’s “7 Sins”
Schacter identifies seven categories of memory errors:
Transience: Forgetting over time.
Absentmindedness: Memory lapses due to inattention.
Blocking: Inability to access stored information.
Misattribution: Incorrect assignment of memories to the wrong source.
Suggestibility: Effects of misinformation altering memory recall.
Bias: Past experiences influence present recollection.
Persistence: Involuntary recollection of memories.
Transience and Storage Decay
Memory decays when unused, represented by Ebbinghaus’ Forgetting Curve, which reveals the rapid loss of newly learned information:
50% retention after 20 minutes.
30% retention after 24 hours.
Interference in Memory
Forgetting can also stem from retrieval failures caused by interference, categorized into:
Proactive Interference: When prior learning hinders new material learning.
Retroactive Interference: When new information disrupts the retrieval of previously learned information.
Strategies to Enhance Memory
Rehearsal: Consciously repeating information to solidify retention.
Chunking: Organizing data into small, manageable units (e.g., formatting phone numbers).
Elaborative Rehearsal: Deepening understanding by relating new information to existing knowledge.
Mnemonic Devices: Tools to aid memory, such as the phrase for planet names: “My Very Educated Mother Just Served Us Noodles.”
Other strategies may include expressive writing, vocalizing lessons, and using melodies to facilitate memorization.
Effective Study Practices
Utilize elaborative rehearsal by linking new information to existing knowledge.
Apply the self-reference effect to make materials personally meaningful.
Advise against neglecting the forgetting curve by routinely revisiting study materials to reinforce retention.
Engage in deep rehearsal focusing on the meaning and contextual associations of the material.
Minimize interference by studying in distraction-free environments.
Maintain physical activity to promote neurogenesis within the hippocampus.
Ensure adequate sleep for memory consolidation processes.
Implement mnemonic tactics to better structure information for retention.