Memory Processes and Models
Memory Overview
Definition of Memory: An active system that receives information from the senses, converts it into a usable format, organizes it as it stores it away.
Example: seeing a dog () is encoded as an image and the word 'dog' in the brain ().
6.1 Three Processes of Memory
Encoding (Getting Information In)
The process of converting sensory input (e.g., sights, sounds) into a format that the brain can use.
Involves mental operations such as transduction: e.g., the ears converting sound vibrations into neural signals; the eyes converting light waves into neural signals.
Variability in Encoding: - Use repetition (to retain) or elaboration (to understand meaning).
Example: repeating a phone number () vs. understanding why a historical event occurred ().
Storage (Keeping Information There)
Maintaining information over time.
Depends on: - Short-term memory (STM): Holds information for approximately 12-30 seconds.
Example: remembering a phone number just long enough to dial it.
Long-term memory (LTM): Stores information permanently or semi-permanently.
Example: recalling your childhood home address.
Retrieval (Getting Information Out)
The process of accessing stored information.
Considered the most challenging part of memory where individuals often struggle to recall information, even if it is stored.
Example: struggling to recall a name even though you 'know' it ().
6.2 Models of Memory
Information-Processing Model
Sensory Memory: - A brief retention of sensory data.
Example: briefly seeing a flash of lightning before processing its shape.
Capacity and duration characteristics:
Capacity: Decent size
Duration: Very short.
Veridical Storage: Retains a truthful representation.
Sperling's Study: Investigated iconic sensory memory with a grid of letters showing that full report is problematic, but partial report indicates all rows are available in memory, illustrating that we briefly store a large amount of visual information, but it fades quickly.
Short-term Memory: - Holds a small amount of information for a short time.
Capacity is traditionally 7 2 items (Miller), e.g., remembering a 7-digit phone number without writing it down.
Chunking: Combining information into meaningful units to extend STM capacity (e.g., remembering the number sequence 177614921945 as three chunks: 1776 (Declaration of Independence), 1492 (Columbus), 1945 (end of WWII)).
Brown et al. (Peterson and Peterson): Studied STM duration and rehearsal blocking.
Long-term Memory: - Sequential processing model: encoding storage retrieval, illustrating memory system interactions.
Parallel Distributed Processing (PDP) Model: - Inspired by AI, processes information across a network of neurons simultaneously which aids faster retrieval.
Levels-of-Processing Model: - Proposes that memory strength depends on depth of processing:
Shallow Processing: Recognizing superficial features leads to weaker memory.
Example: remembering the font of a word without recalling its meaning.
Deep Processing: Engaging with meaning leads to stronger memory retention.
Example: understanding the plot of a novel compared to just skimming it.
6.3 Sensory Memory Detailed
Definition: The initial stage of memory; briefly holds incoming sensory information as neural messages, acting as a filter to perception.
Only some information passes through for further processing.
Example: smelling smoke () and only focusing on the 'fire' aspect while ignoring other background smells.
Iconic Memory (Visual Sensory Memory): - Duration: Lasts a fraction of a second.
Function: Maintains stable visual experiences during rapid eye movements (microsaccades).
Masking: New input quickly replaces old information.
Sperling’s Experiment: Utilized a grid to illustrate that participants store an entire image for a brief time, confirmed via partial report method.
Eidetic Imagery: Rare ability to retain images in detail over time; more common in children and fades with age.
Highly Superior Autobiographical Memory (HSAM): Exceptional ability to recall personal events in vivid detail.
Example: a child describing a picture in extreme detail minutes after seeing it, as if it's still present.
Visual Persistence: Explains light trails seen from sparklers.
Microsaccades: Tiny eye movements preventing visual fading.
Echoic Memory (Auditory Sensory Memory): - Duration: Lasts 2-4 seconds, longer than iconic memory.
Capacity: Limited to sounds perceptible at one time.
Function: "What?" phenomenon aiding with auditory processing.
Example: asking 'What did you say?' but then recalling the words before the person repeats them.
Key Terms: - Reticular Formation: Detects significant sensory information.
6.4 Short-Term Memory vs. Working Memory
Short-term Memory (STM):
Holds information for about 12 to 30 seconds without rehearsal.
Encoding: Primarily auditory; internal auditory dialogue prevalent.
Example: silently repeating a new acquaintance's name to remember it.
Capacity: 7 2 items (Miller) vs. newer findings suggesting 3-5 items (variable with age/complexity).
Chunking: Grouping information enhances STM capacity.
Maintenance Rehearsal: Repetition retains information longer.
Example: repeating a grocery list to yourself until you reach the store.
Selective Attention: Filters which sensory inputs enter STM.
Example: focusing on a friend's voice in a noisy crowd.
Broadbent’s Filter Theory: Important stimuli alone pass through a 'bottleneck' into STM.
Example: only processing the message from your boss in a meeting and ignoring background chatter.
Treisman's Attenuation Model: Less important stimuli are weakened in processing rather than completely discarded.
Example: in a noisy party, you might faintly hear your name from across the room even though you were focusing on a conversation with someone else.
Working Memory (WM):
An active system for processing and manipulating information in STM.
Baddeley & Hitch Model: Components include: - Central Executive: Directs attention and coordinates the subsystems.
Example: planning your day, deciding which tasks to do first.
Visuospatial Sketchpad: Manages visual and spatial information.
Example: mentally rotating an object to see how it fits into a space.
Phonological Loop: Manages auditory information.
Example: remembering a phone number by repeating it to yourself.
Revised Model: Adds Episodic Buffer integrating STM and LTM.
Example: imagining a past vacation by integrating visual memories () with sounds () and knowledge of the event ().
Utility of WM Research: Improves understanding of teaching strategies and investigations into ADHD, aging, and other neurological conditions.
6.5 Long-Term Memory Processes
Long-Term Memory (LTM): - Duration: Changes in the brain are relatively permanent.
Capacity: Seemingly unlimited.
Encoding: Acquires meaningful forms (images, sounds, smells).
Example: recalling the smell of your grandmother's cooking or the layout of your childhood home.
Max Capacity and Duration.
Rehearsal: Linear repetition not effective for retention.
Organization: Effective use of other meaningful structures.
Example: grouping historical events by century or topic simplifies recall.
Elaboration: Tying new info to existing knowledge significantly enhances retention.
Example: connecting the concept of 'memory encoding' to your own experience of studying for an exam.
Types of Long-Term Memory:
Nondeclarative (implicit) memory: - Lacks conscious recollection (e.g. skills like walking).
Stores learned skills, habits, and conditioned responses in areas like the amygdala and cerebellum.
Example: riding a bike, typing on a keyboard, or classical conditioning like salivating at the sound of a bell.
Declarative (explicit) memory: - Conscious knowledge of facts/events (semantic vs. episodic):
Semantic Memory: General knowledge and concepts.
Example: knowing that Paris is the capital of France, or that a 'cat' is an animal.
Episodic Memory: Personal experiences tagged in time (e.g. details of a vacation).
Example: remembering your last birthday party, or what you ate for breakfast this morning.
Autobiographical Memory: Encompasses both semantic and episodic memory components.
Example: recalling details about your high school graduation, including facts about the speakers and personal feelings.
Memory Encoding Techniques: - Maintenance Rehearsal: Less effective for long-term memory.
Example: reciting random numbers to keep them in mind for a few seconds.
Elaborative Rehearsal: More adaptive, promotes integration with existing knowledge.
Example: creating a story or a mental image involving new vocabulary words to better remember their definitions.
6.6 Effects of Cues on Memory Retrieval
Retrieval Cues: Stimuli aiding access to stored memories.
Elaborative Rehearsal: Integrating meaning generates multiple cues, easing recall versus mere repetition.
Example: understanding the cause and effect of historical events creates multiple retrieval paths, rather than just repeating dates.
Priming: Enhances memory retrieval unconsciously through prior exposure.
Example: if you recently saw the word 'doctor,' you are more likely to complete 'NUR_E' as 'NURSE' unconsciously.
Encoding Specificity: Suggests that retrieval is improved when the context during recall aligns with that during encoding.
Context-dependent Learning: The physical environment serves as cues (e.g., taking a test in the same seat).
Example: performing better on a test when you study in the same classroom where the test will be held.
State-Dependent Learning: Memory retrieval is influenced by psychological or physiological states (e.g., emotions impacting recall).
Example: recalling happy memories more easily when you are in a good mood.
6.7 Recall vs. Recognition Retrieval Processes
Recall: - The act of retrieving information with minimal to no external cues (e.g., essay questions).
Associated with the tip-of-the-tongue (TOT) phenomenon linked to brain areas like the fusiform gyrus.
Recognition: - Identifying information presented with cues (e.g., multiple-choice tests).
Generally easier than recall and has a highly accurate retrieval for images, especially faces, though risks false positives.
Example: recognizing familiar faces in a crowd, or picking out the correct answer from a list of options on a multiple-choice exam.
Serial Position Effect: - People remember items at the beginning (primacy effect) and the end (recency effect) of a list better than those in the middle.
Example: remembering the first few and last few items on a shopping list, but forgetting those in the middle.
This has implications for job interviews and study strategies (e.g., reviewing notes before exams).
Testing Effect: - Practicing retrieval enhances long-term memory and reinforces learning.
Example: self-quizzing or practicing retrieval of information rather than just rereading notes, leading to better exam performance.
Eyewitness Testimony: - Research by Elizabeth Loftus reveals memory as a reconstructive process, easily swayed by post-event information leading to potential inaccuracies.
Example: someone incorrectly identifying a suspect in a lineup because they were influenced by leading questions about the event.
Individuals with HSAM are also prone to memory distortions despite their vivid recall.
6.8 Automatic Encoding of Memories
Automatic Encoding: - Some memories enter long-term storage without conscious effort.
Example: remembering what you ate for lunch yesterday without actively trying, or the route you took to school this morning.
Individuals may remember time, space, and frequency of occurrences automatically.
Flashbulb Memories: - A specific type of automatic memory formation during emotionally charged events (e.g., trauma).
Example: vividly remembering where you were and what you were doing when a major event like occurred.
Often described as vivid and detailed, though not always more accurate than standard memories.
6.9 Constructive Processing and Memory Retrieval Issues
Constructive Processing: - Memory is not verbatim but reconstructed at every retrieval instance.
Described by Sir Frederic Bartlett as a narrative-building process influenced by prior knowledge.
Hindsight Bias: Alters perceptions post-event, creating a false sense of having known before learning new information.
Example: after an event, saying 'I knew that would happen all along,' even if you didn't.
Memory Retrieval Problems: - Total recall is rare; most individuals face inaccuracies.
Misinformation Effect: Example where the introduction of misleading information alters original memory (e.g., after watching a simulated car crash, if asked 'How fast were the cars going when they smashed into each other?', witnesses estimate higher speeds and report seeing broken glass (even if none was present) compared to being asked 'How fast were the cars going when they hit each other?').
False Memory Syndrome: The impact of suggestion, hypnosis, or social pressure in forming recollections of events that never occurred.
Example: a patient under hypnosis recalling a traumatic childhood event that never actually took place, due to therapist suggestion.
Factors Influencing False Memories: - Plausibility: Higher chances of false memories for plausible events.
Example: it's easier to implant a false memory of getting lost in a mall as a child than a false memory of flying to the moon.
Feedback/Suggestion: Increased personal relevance enhances false memory formation.
Example: if a therapist or interviewer repeatedly suggests that a certain event might have happened, an individual might start to 'remember' it.
Individual Differences: Trauma, depression, or PTSD can escalate vulnerability to false memories.
Example: someone experiencing depression might be more susceptible to negative false memories.
Schemas and Culture: Individual backgrounds shape memory processing and distortion susceptibility.
Example: cultural narratives about family or community events can shape how individuals 'recall' their own experiences.
6.10 Biological Bases of Memory
Nondeclarative (Implicit) Memory
Hippocampus: Involved when relational or stimulus-reward learning occurs.
Cortex: Priming.
Striatum: Procedural memory.
Amygdala: Emotional responses.
Cerebellum: Skeletal musculature, reflex pathways, nonassociative learning.
Declarative (Explicit) Memory
Includes semantic (facts) and episodic (events) memory.
Medial Temporal Lobe and especially Hippocampus.
Working and Short-Term Memory
Prefrontal Cortex (PFC): Maintains and rehearses items in working memory. Works with inferior temporal cortex, perisylvian cortex, and posterior parietal cortex.
Broca's Area: Rehearses verbal information.
Wernicke's Area: Comprehends and represents words.
Memory Formation and Consolidation
Synaptic Plasticity: Changes in receptor sites, synapse sensitivity (long-term potentiation), and dendritic proteins.
Molecular Mechanisms: , , , .
Consolidation: Structural and functional changes across neurons, from minutes to years.
Sleep and Memory
N2 Sleep: Sleep spindles.
Slow-Wave Sleep (SWS): Benefits declarative memory.
REM Sleep: Enhances emotional and procedural memory.
Posterior Cingulate Cortex: Involved in episodic memory retrieval and rehearsal.
Thalamus: Temporarily retains sensory info before processing.
Association Areas: Likely storage sites for semantic and long-term memory.
6.11 Biological Causes of Amnesia
Types of Amnesia
Retrograde Amnesia: Loss of memory from injury or trauma, disrupts memory consolidation.
Anterograde Amnesia: Inability to form new memories after an injury (e.g., Dementia and Alzheimer’s disease).
Alzheimer’s Disease
Most common form of dementia.
Progresses from anterograde to retrograde amnesia.
Associated with brain atrophy, beta-amyloid plaques, and tau tangles.
Risks: Genetics, hearing loss, hypertension, diabetes.
Incurable, treatment can only slow the disease.
Infantile Amnesia
Most people can't recall events before age 3.
Due to early memories being implicit and an underdeveloped hippocampus.
Brain Areas and Memory Types (Summary)
Procedural Memory: Cerebellum.
Short-Term Memory: Pre-frontal cortex and temporal lobes.
Semantic and Episodic Long-Term Memory: Frontal and temporal lobes.
Hippocampus: Crucial for forming new declarative long-term memories.
Reliability of Memory
Overall, memories are seldom completely accurate and degrade over time.
Conditions under which false memories can occur are much more flexible than the processes which allow for true recollection.
Variation in individual and cultural factors significantly influences memory formation and reporting.