Memory Flashcards
What is memory
Memory is a change in the brain or mind following experience
Processes that retain, retrieve and use info after stimuli is no longer present
Activity-dependent memory
Short-term memory
Structural memory
Long term
Early theories of memory
19th century - William James
Distinguished primary and secondary memory
Primary memory
Things we are presently aware of
Current consciousness content
Secondary memory
Mental representations of distant past
Not in current consciousness
Must be bought back by retrieval process
Modal model of memory (basics)
Atkinson and shiffrin (1968) Computer as model for human cognition Memory is an integrated system that processes info Eg - encoding, storage, retrieval components do not act in isolation Memory has a limited capacity
Modal model of memory diagram
Input → sensory memory → STM → (encoding or retrieval) LTM
In STM there’s control processes - active processes that can be controlled by the person eg - rehearsal, imagery, attention
STM where output occurs
Sensory memory
‘Buffer’ that briefly holds all info from senses
Vast capacity and short timescale
Collects and holds info for initial processing which helps fill in the blanks
Iconic memory
Sensory memory for visual info
Helps explain persistence of vision illusion - New info blends with info already in iconic memory
Eg - sparklers trail of light
Capacity and duration of iconic memory
When told where to focus memory is better
Sterling (1960) - whole report all letters 37.5%, focused (partial) report 82.5%
Delayed partial (focused) worsens performance
Change blindness
An interruption erases iconic memory
Stops from registering differences in 2 scenes
Coordination of sensory processing
To bind info from senses we need to be able to remember it all together
Abc/12,13,14 - context from prefrontal cortex to processing areas of brain - info needs to be held in iconic memory
Short term memory
Stores small amount of info for short time
New info from senses and recalled info from LTM
Duration and capacity increased by control processes (rehersal)
Only had STM
Clive wearing - medial temporal lobes damaged
Still has STM and LTM for prior damage events
No longer encode new LTM
Duration of STM
When rehearsal is prevented STM has a duration of 15-20 seconds
3 Seconds interrupted recall 80%
18 seconds interrupted recall 10%
Capacity of STM
Digit span task - typically remember 5-9 items
Miller’s law of 7 +/- 2
Chunking
Collection of elements strongly associated with each other but weakly with other chunked items
Eg-phone number
People can improve chunking
Ericcson(1989) - trained college student from digit span of 7 to 79 after 230 1 hour sessions
Eg - chess pieces randomly positioned master and beginner performed same
Item complexity
Not all items are equal - some require more mental resources to hold in memory
Eg- highest-lowest capacity = coloured shapes, Chinese letters, random polygons, shaded cubes
Auditory coding STM
More likely to make mistakes with similar sounding letters eg- T V P
Less likely to make mistakes based on visual similarity
Coding of info in STM is auditory
Visual coding STM
Some STM coding must be visual as we can recall complex patterns difficult to verbalise
Semantic coding STM
STM must involve some semantic coding and not just lower level features (visual and auditory)
Proactive inference - previously remembered items interfere with subsequent items = cannot be recalled accurately
Memory is released from proactive interference when items come from different categories
Eg professions for 3 trials then fruit for 1 = last and first remembered much better
Working memory
Limited-capacity system for temporary storage and manipulation of info for complex tasks
Eg - comprehension, learning, reasoning
STM and working memory distinction
Subtle but important
STM is onecomponent of working memory
STM holds info for brief period while working memory processes and manipulates info for complex cognition
Example: STM repeat digits, working memory repeat digits in reverse
Limitations of modal model
1- seem to be multiple STM stores (verbal, visual, semantic)
2- doesn’t explain how info is manipulated during problem solving
Baddeleys working memory model
Phonological loop and visuospatial sketch pad are STM stores with different types info coding
The central executive coordinates and manipulates info from these stores eg focusing attention on relevant info
Phonological loop
Specialised for verbal and auditory info
2 parts:
1- phonological store: where info is temporarily held
2- articulatory control process: ‘inner speech’ -has a fixed duration and constantly repeats info from store to prevent it disappearing
Evidence for phonological loop
1: phonological similarity effect- letters/words most likely to be mistaken for similar sounding ones
2: articualtory suppression: repeating a seperate word aloud interrupts with working memory for verbal stimuli
3: word length effect: memory’s poorer for long words - long words take longer to rehearse so phonological loop gets to practice less in its fixed duration
Visuospatial sketchpad
Stores visual and spatial info eg- maps, pictures, objects
Mental images
Evidence for mental imagery is from mental rotation studies (cube diagrams more rotation = longer reaction time)
Distinct phonological and visuospatial memory stores
Brooks (1968) - participants memorised sentences in either store then mentally considered words and answered with either store.
Participates were slower when responses required same memory store as the stimulus uses to be memorised
Central executive
Controls focus of attention (focus, switching, divided attention)
Controls suppression of irrelevant info
Also retrieves and manipulates info from stores
What makes working memory work
Engrams
Memories are stored in cell assemblies called engrams
Re-activation of engrams by recall strengthens connections between cells = consolidation of memory
Nuerons that fire together wire together
Same cells can be used in many engrams
Double dissociation
Different memory stores are described as dichotomies
Some people blind but not deaf show double dissociation between sight and vision = senses must be independent in brain
Anterograde amnesia
Inability to form new memories
Retrograde amnesia
Inability to access old memories
Double dissociation: STM and LTM
Patient 1: temporal lobotomy = anterograde amnesia effects specific to declarative memory (explicit memory)
Patient 2: Damage parietal lobe = poor verbal STM, visospational STM intact (can read) and form LTMs
Semantic memory
Holds info for facts
Eg- Brisbane is QLD biggest City
Type of explicit memory
Episodic memory
Holds memories of experiences. Events
Eg - I remember when I was in Brisbane we travelled to the zoo
Type of explicit memory
Double dissociation: episodic and semantic memory
Patient 1: medial temporal lobe and hippocampus damage = severe anterograde amnesia and retrograde amnesia for episodic memory but intact semantic memory
Patient 2: left temporal lobe damage = impaired semantic memory
LTM and temporal lobe
LTM deficits = temporal lobe damage
Within temporal lobe hippocampus important for laying down new LTMs
Doesn’t mean memories stored in temporal lobe - more likely its crucial in retrieval
No single place for LTM storage
Working memory and prefrontal cortex
Delayed response task and single neuron recordings in monkeys show that the prefrontal cortex is important for working memory
Distributed representations
Like other memory types, working memory relies on distributed neural representations
Primary auditory cortex involved in auditory working memory - more activation in 2 back than 0 back (because requires working memory to manipulate in 2 back)
Explicit and implicit memory
Explicit is declarative and conscious
Implicit is non-declarative and unconscious
Where is explicit memory held
Medial temporal lobe
Types of implicit memory.
Procedural memory - know cake recipe
Perceptual priming
Classical conditioning
Non-associative learning - habitation or sensitisation
