Lecture 5 & 6 - Memory Flashcards
What is memory?
Processes involved in retaining, retrieving and using information about a stimuli, images, events. Ideas and skills after the original information is no longer present
Active any time some past experiences has an impact on how you think or behave now or in the future
Memory is a behaviour of neurones, not a passive storage
Memory types and storage length
Sensory memory - initial stage that holds all incoming information for seconds or fractions of a second
Short-term memory - holds 5 to 7 items for about 15 to 20 seconds
Long term memory - can hold a large amount of information for years of even decades
Modal memory of memory
Atkinson and Shiffrin’s (1968) model of memory conatins features of many of the memory models that were being proposed in the 1960s
Sensory, short-term memory and long-term memory were understood as structural fesatures
Different types of memory work together at al times
Control processes - active processes that can be controlled by the person
- rehearsal
- strategies used to make a stimulius more memorable (e.g. connecting to existing knowledge, mnemotechniques)
- strategies of attention nthat help you focus on specific stimuli (e.g. memorising details)
The primary form of information less from ASTM is through decay
Sensory memory
Sensory memory:
- retention of the effects of ness Roy stimulation for brief periods of time
- information decays very quickly
Persistence of vision:
- retention of the perception of light
- trial of light from a moving sparkler
- frames in film
Capacity of sensory memory
Sperling (1960) attempted measuring the capacity and duration fo sensory memory
- presented an array of letters flashing quickly on a screen
- ppts asked to report as mnay letters as possible
Whole report method:
- ppts asked to report as many as could be seen
- average of 4.5. Out of 12 letters *37.5%)
Partial report method:
- ppts heard tone that told them which row of letters to report
- average out 3.3. Our of 4 letters *82%)
- ppts could report any of the rowsa
Delayed partial report method:
- presentation of tone delayed for a fraction of a second after the letters were extinguished
- average of 1 out of 4 letters (25%)
- performance decreases rapidly
Results of Sperling’s (1960) partial report experiments:
The decrease in performing is due to the rapid decay of iconic memory (=sensory memory in the modal model)
The letters that wer reported were moved form sensory memory to short term memory
Short-term memory (STM)
Stores small amounts of information for a brief duration
Includes new information received from the sensory stores and information recalled from long term memory
What we expeirnce as the present
Duration of STM
15-20 seconds
STM duration is tested with recalling letter and digit series tasks
- ppts read aloud a series of letters and/or digits
- recount them backwards
- after a set time (decay interval), they recall a part of the series
After 3 seconds,ppts performed at 80%
After 18 seconds, ppts performed at 10%
Reductions in performance is explained by decay, the vanishing of a memory trace due to the passage of time and competing stimuli
Is decay the only reason?
Revisiting data from the experiment revealed that the poor performance after long intervals happened towards the end of the experimenter and not in the beginning
Proactive interference: previous knowledge interferes with new information
Retroactive interference: new information interferes with existing knowledge
How big is the STM?
Digit span task: how many digits a person rember
- typical result: 5 to 8 bites (magic number is 7+/-2)
- lasts 15 to 20 seconds or less
What is an item
- about individual letter sequences
Chunking
- small units can be combined into larger meaningful units
- very effective learning strategy and STM and control process
Chunk:
- a collection of elements strongly associated with one another but bleakly associated with elements in other chunks
- increases capacity for STM
Digit span task:
- 5-9 numbers
- 5-9 letters or ciders
5-9 words or numbers
- 5 to 9 images/memes/faces
Change detection paradigm
STM test that prevents chunking strategies cia meaningful units Luck and Vogel (1997)
- memory capacity = amount of information rather than number of items
- used coloured squares as well as complex objects to prevent (verbal) rehearsal
Alvarez and Cavanagh (2004)
- results showing the average number of objects that could be remembered for each type of stimulus
- true STM capacity (without chunking) is liekly around 4 fr most people
Working memory
Baddeley and Hitch (1974)
WM is a limited capacity system for temporary storage and manipulation of information for complex tasks such as comprehension, learning and reasoning
WM differs from short-term memory
- STM holds information for a brief period of time
- WM stores, processes and manipulates and is active during complex recognition
Differences from STM:
- dynamic system
- subdivision
- facilitates parallel processing
- interferes if similar information types are processes Ed simultaneously
Phonological loop
Verbal and auditory information
Two components:
- phonological store - limited capacity for verbal and auditory information, only hold information for few seconds
- articulately rehearsal process - responsible for research that keeps information from decaying
Visuospatial sketch pad
Holds spatial and visual information (visual imagery) in the mind is absence of a physical visual stimulu
Mental rotation task:
- tasks that need more rotations ind the mind take longer
The central executive
Acts as the attention controller and access long term memory
Focuses, divides, switches attention
Contra;s suppression of irrelevant information and phonological loop and visuospatial sketch pad
Perseveration: typical behaviour patients with damage in frontal lobe, repeatedly performing the same action nor thought even it is not achieving desired f goal -> damage to central executive
WM capacity
Tested with reading span task and operation span task (diagnostic tool to assess individual differences in WM)
WM capacity is affected by interference e.g.:
Phonological similarity affect
- letters or words that sound similar are confused
Articulatory suppression
- speaking prevents ppt from rehearsing items to be remembered
Word length effect
- memory for wordlists is better for short words
- it takes longer to rehearse long worlds and to produce them during recall
What makes a good WM?
Having a good WM is not so much about amount of infro you can hold in WM, but the efficiency with which you can control different processes (e.g. attentional control)
The episodic buffer
Baddeley’s revised working memory model (200() added the episodic buffer
Back up store that can hold information long and has greater capacity than PL or VSP
Uses techniques like chunking
Communicated with long-term memory and working memory components
Other WM models
Difference between WM and LTM is defined by which information si currently achieved
Central executive is controlling nformation and deactivation
While these models cannot explain everything, they are more in line with neuroscientists data (neural coding, memory as behaviour)
Working memory and the brain
The neural basis of WM is highly influenced by task and context
There is not 1 neural correlate of WM
From a neural perceptive, WM is a bhevaiour of neurones (being active) while controlled attenton (executive function) mediates different processes
Executive function and attention do have clear brain network - WM is not localised
Prefrontal cortex responsible for progressing incoming visual and auditory information
- monkeys without a pre frontal cortex have difficulty holding information in working memory
Funsahashi and coworkers (1989)
- single cells recordings form monkey’s prefrontal cortex during a delayed-response task
- neurones that responded to stimulus location kept firing for the delay time
Long term memory
Archive of information about past events and knowledge
Works closely with working memory
Storage stretched form a few moments ago to as far back as one can remember
More recent memories are more detailed
Thre process of moving information from Wm to LTM is called consolidation
Different types of LTM
Explicit (conscious)
- episodic memory (experiences in the past)
- semantic memory (facts, knowledge)
Implicit (not conscious/non-declarative)
- procedural memory
- priming
- classical conditioning
Duration
Covers a span that stretched from about 30 seconds ago to your earliest memories
Serial position curve
Distinction between STM and LTM using the serial position curve (Murdoch 1962)
Read word list -> write down all words remembered
Memory is better for words presented at the beginning o the list (primary effect) and at the end (recency effect)
Coding in WM and LTM
Coding happens on all levels (e.g. auditory, visual, semantic)
Sensory coding (sensory memory and WM) is encoded into mental coding (LTM)
Recognition memory: identification of a previously encountered stimulus
Exmaple:
You don’t remeber the exact wording of most stances after an while, but you will remeber the semantic/content (information had moved from snesnroy memory/WM to LTM)
Locating memory in the brain
Patient HM: surgery removed hippocampus
- retained STM BUT UNABLE TO TRANSFER INTO LONG-TERM
-unable to form new LTMS
Patient KF: accident damaged parietal lobe
- impaired STM (rescued digit span) but functional LTM
- able t form and hold new memories
Highlights the role of hippocampus for encoding information and the parietal lobe for attention and LTM
Declarative memory: Episdic vs semantic (Tulving 1985)
Episodic:
