ITP Topic 6 Memory

Memory

the ability to store and retrieve information, allowing organisms to retain experiences for later use

Perception

The organization and interpretation of current sensory information to understand our environment.

Amnesia

a deficit in long term memory — resulting from disease, brain injury, or psychological trauma — in which the individual loses the ability to retrieve vast quantities of information

Amnesia types

• Retrograde amnesia: loss of past memories for events, facts, or people

• Anterograde amnesia: inability to form new memories

Amnesia types

Retrograde amnesia

loss of past memories for events, facts, or people

Amnesia types

Anterograde amnesia

inability to form new memories

Explicit (declarative) memory

Memory that involves conscious recollection of information.

It includes:

• Episodic memory – personal experiences/events

• Semantic memory – facts and general knowledge

Episodic memory (what is it, and the brain region)

• a subtypes of explicit memory

• personal experiences tied to a specific time and place

• medial temporal lobe, especially the hippocampus (for formation); sensory cortex (for storage)

Sematic memory (what is it, and the brain region)

• a subtype of explicit memory

• knowledge of facts, concepts, and categories, independent of personal experience (e.g. the capital of Canada)

• medial temporal lobe (acquisition); cortical regions

Implicit (non-declarative) memory

Memory that influences behaviour without requiring conscious recollection.

it includes:

• procedural memory, priming, classical conditioning, and non-associative learning.

Procedural memory(what is it, and the brain region)

• subtype of implicit memory

• motor skills, cognitive skills, and habit (e.g. riding a bike, reading)

• Basal ganglia, cerebellum

Priming

• subtype of implicit memory

• facilitated response to a stimulus die to recent experience (perceptual or conceptual)

• relevant sensory/conceptual processing circuits

classical conditioning (in terms of implicit memory) (what is it, and the brain region)

• subtype of implicit memory

• learned associations between stimuli

• basal ganglia, amygdala, cerebellum

non-associative learning as implicit memory (what is it, and the brain region)

• subtype of implicit memory

• habituation and sensitisation (changes in response to repeated stimuli)

• neurons involved in perception

Memory operates over time in three phases

• Encoding: taking in information and converting it into a memory

• Storage & consolidation: maintaining and stabilizing information in memory traces

• Retrieval: accessing stored information

  • Recall: producing information from memory

  • Recognition: identifying previously encountered information

Encoding

the process of transforming perception into a memory. it can be automatic or effortful

Factors influencing encoding

• attention: the more attention paid to a stimulus, the more likely it is to be encoded. without attention, even familiar details (like the layout of a penny) are often not encoded

• duel-coding hypothesis: information coded both verbally and visually is remembered better than information coded only verbally. concrete words (e.g dog) are easier to encode than abstract ones (e.g keep)

Levels of processing model

• Visual (shallow): process appearance — “Is CAT in capitals?”

• Acoustic (medium): process sound — “Does cat rhyme with hat?”

• Semantic (deep): process meaning — “Is a cat an animal?”

Rehearsal strategies

1. maintenance rehearsal: repeating an item over and over (shallow)

2. elaborative rehearsal: linking new information to existing knowledge or making it personally relevant (deep)

Organisational tools

• schemas: cognitive structure that help perceive, organise, and understand information based on past experience (e.g a “grocery shopping” schema). they can lead to errors if the new situation differs from the schema

• chunking: breaking down information into meaningful units

• mnemonics: strategies to improve recall through retrieval cues:

  • method of Loci (memory palace): associating items with physical locations

  • Peg method: hanging memories on mental “pegs”

  • Story method: linking items into a narrative

Organisational tools

Schemas

cognitive structure that help perceive, organise, and understand information based on past experience (e.g a “grocery shopping” schema). they can lead to errors if the new situation differs from the schema

Organisational tools

Chunking

breaking down information into meaningful units

Organisational tools

Mnemonics

• strategies to improve recall through retrieval cues:

  • method of Loci (memory palace): associating items with physical locations

  • Peg method: hanging memories on mental “pegs”

  • Story method: linking items into a narrative

The Atkinson and Shiffrin model (1968) proposes three distinct storage system

1. Sensory memory: a temporary system tied to sensory input, lasting only a fraction of a second.

   1. iconic memory: visual sensory memory (1/3 of a second)

   2. echoic memory: auditory sensory memory (allows you to repeat the last few words spoken to you)

2. Working memory (short-term): an active process that retains and manipulates information for 10-30 seconds

   1. capacity: historically cited as 7±2 items (Miller, 1956), though recent research suggests it may be as few as 4 items

   2. maintenance: requires active focus or rehearsal; distraction causes rapid forgetting

3. Long term memory (LTM): a relatively permanent storage system with limitless capacity, lasting from minutes to a lifetime

Sensory memory

(Atkinson and Shiffrin)

• a temporary system tied to sensory input, lasting only a fraction of a second.

  • iconic memory: visual sensory memory (1/3 of a second)

  • echoic memory: auditory sensory memory (allows you to repeat the last few words spoken to you)

Working memory (short-term)

(Atkinson and Shiffrin)

• an active process that retains and manipulates information for 10-30 seconds

  • capacity: historically cited as 7±2 items (Miller, 1956), though recent research suggests it may be as few as 4 items

  • maintenance: requires active focus or rehearsal; distraction causes rapid forgetting

Long term memory (LTM)

(Atkinson and Shiffrin)

• a relatively permanent storage system with limitless capacity, lasting from minutes to a lifetime

Serial position effect

• primacy effect: better memory for items at the start of a list (encoded into long term memory)

• recency effect: better memory for items at the end of a list (still in working memory)

Consolidation

it is the gradual process of forming lasting neural connections

so encoded information becomes stored in memory → transient and fragile potential memory contents are transformed into a more permanent state

Consolidation:

Long term Potentiation (LTP) and NMDA receptors

the strengthening of synaptic connections, making postsynaptic neurons more easily activated. this supports Hebbs law: “cells that fire together wire together”

NMDA receptors: glutamate receptors critical for LTP

Factors enhancing consolidation

• sleep: neural circuits replay memories during sleep, strengthening connections

• emotion: the amygdala facilitates consolidation in the hippocampus and basal ganglia when an event triggers autonomic arousal (stress hormones)

Reconsolidation

and

memory updating and memory strengthening

when a memory is retrieved, it enters an active state and must be stored again. this allows for:

• memory updating: incorporating new relevant information

• memory strengthening: making the memory more durable (triggered by retrieval practice)

Retrieval

The expression of stored memories — bringing previously stored information back to mind.

Principles of retrieval

• encoding specificity principle: any stimulus encoded with an experience can trigger its memory

  • context-dependent memory: better recall when the physical environment matches the encoding environment

  • state-dependent memory: better recall when internal states mood, intoxication) match at encoding and retrieval

• prospective memory: remembering to perform a future task. this often requires external cues (alarms, sticky notes) to avoid the effort of active monitoring

Principles of retrieval:

Encoding specificity principle

• context-dependent memory

• state-dependent memory

• any stimulus encoded with an experience can trigger its memory

  • context-dependent memory: better recall when the physical environment matches the encoding environment

  • state-dependent memory: better recall when internal states mood, intoxication) match at encoding and retrieval

Principles of retrieval

Prospective memory

remembering to perform a future task. this often requires external cues (alarms, sticky notes) to avoid the effort of active monitoring

Patterns of forgetting

• Ebbinghaus forgetting cues: forgetting is rapid initially and then levels off. if a memory persists for 5 years, it is likely to last a lifetime

• retrieval induced forgetting: retrieving one item from LTM can impair the ability to recall related items (e.g remembering “apple” from a list makes it harder to later remember “orange”)

Memory distortions

• flashbulb memories: vivid episodic memories of surprising, consequential, or emotional events (e.g 9/11)

  • accuracy: while people are highly confident in these memories, details are often inconsistent and inaccurate over time

• source misattribution: forgetting the origin of a memory

• false memories: constructing memories of events that did not occur, often influenced by schemas or misleading information

Memory distortions:

Flashbulb memories

• vivid episodic memories of surprising, consequential, or emotional events (e.g 9/11)

  • accuracy: while people are highly confident in these memories, details are often inconsistent and inaccurate over time

Memory distortions:

Source misattribution

forgetting the origin of a memory

Memory distortions:

False memories

constructing memories of events that did not occur, often influenced by schemas or misleading information

Absentmindedness

the inattentive or shallow encoding of events

Memory decay

forgetting over time

Proactive interference

Old information interferes with remembering new information.
Example: You keep typing your old password instead of your new password.

PROactive = Past → interferes with Present/new

Retroactive interference

New information interferes with remembering old information.
Example: After learning your new password, you struggle to remember your old password.

RETROactive = Recent/new → interferes with old

Memory bias

the changing of memories over time so that they become consistent with current beliefs or attitudes

Suggestibility

The development of biased memories due to misleading information. Memories can be altered or even implanted by false information, leading questions, or existing knowledge/associations.

Example: Loftus showed that changing the wording of questions after an event can change how people remember the event.