Cognitive neuroscience of memory Flashcards
What are the stages in memory processing?
- Encoding of information into memory
- Storage of information into memory systems
- Retrieval of information from memory
What is the multi-store model for memory?
- Sensory memory: Brief store of sensory information that does not need to be attended to.
- Short-term store: Holds information for longer period of time that requires attention (limited capacity).
- Long-term store: Information from short-terms store passes into this and can be held for indefinite amount of time (virtually unlimited capacity).
Who proposed the multi-store model?
Atkinson & Shiffrin (1968)
What type of information is stored in sensory stores?
- All information detected by sensory systems.
- Stores are independent of attention.
What are the types of sensory stores?
- Iconic memory: Visual information
- Echoic memory: Auditory information
What was the experiment on iconic memory performed by Sperling?
- Subjects were presented with 3x4 grid of random letters for 50 ms.
- An auditory cue was then played (high, medium, low) after set time intervals, prompting subject to recall all letters in line indicated.
- This was called a “partial report” condition.
What is the duration of iconic memory?
~1 second
What was the experiment on echoic memory performed by Treisman?
2 different audio messages were played in the ears of subjects while the subject was asked to repeat out loud (i.e. attend) to the message in one ear while ignoring the message in the other.
What is the duration of echoic memory?
~2 seconds
What is short-term memory?
STM is used to hold information ‘in mind’ for short periods of time while performing complex tasks.
What is the capacity of short-term memory?
7 ± 2 chunks
What is the duration of short-term memory?
A few seconds
What is loss of information from short-term memory mediated by?
Displacement by interference, with no contribution from temporal decay
What was the experiment on short term memory performed by Waugh & Norman?
- Subjects were presented with a string of 16 numbers under 2 conditions:
- Slowly with long intervals between numbers
- Quickly with short intervals between numbers - Subjects were then asked to count backwards and then recall the numbers in digit string.
What was the purpose of the Waugh & Norman experiment?
Showed that loss of information from short term memory was due to displacement, not decay.
What are the criticisms of the multi-store model for short-term memory?
- According to the model, memory processing is linear, in the sense that information needs to pass through each store before entering the next. Evidence against this comes from the fact that in patient KF, who suffered brain damage leading to a short-term memory deficit, but no long-term memory deficit.
- Another assumption made by the model is that each type of memory uses a uniform store for all information. Evidence for this again came from KF who had worse STM deficits for auditory and numerical information than visual information, suggesting different stores for these types of information.
What is the working memory?
- Central executive: Modality-free and is responsible for selecting information from the 2 associated stores.
- Phonological loop: Stores auditory information (and auditory representation of other forms of information).
- Visuo-spatial sketchpad: Stores visual and spatial information.
What is the phonological similarity effect?
Subjects were much better at remembering phonologically distinct words than phonologically similar words, implying that this information was stored in an auditory-dependent manner.
What is the explanation for the phonological similarity effect?
There is confusion between the similar sounding words in the phonological store, making recall much more difficult.
What is the word length effect?
- Subjects were much better at remembering shorter words compared to longer words.
- In addition, individuals who spoke languages where digits could be spoken much more quickly had longer digit spans compared to English.
- This effect was eliminated when articulatory suppression was used (subjects were asked to silently mouth digits).
What is the explanation for the work length effect?
- All information regarding language needs to be converted to auditory information in order to be stored into working memory, a process carried out by the “articulatory control process” .
- The longer the words are, the longer it takes for them to be spoken, the fewer times they can be rehearsed in a given time interval, the less likely they are to be remembered.
- When articulatory suppression was used, the articulatory control process was occupied so that it cannot be used for rehearsal, decreasing performance of both long and short word recall equally as short words no longer benefit over long words via this process.
What are the components of the visuo-spatial sketchpad?
- Visual cache: All visual information regarding form and colour pass into this first. Information here can be displaced by new visual information.
- Inner scribe: Visual information passes into this component where it can be rehearsed. This component also used for spatial processing.
What are the similarities between the phonological loop and the visuo-spatial sketchpad?
Phonological loop = Visual cache
Articulatory control process = Inner scribe
What is the recency effect?
Items at the end of a list are often remebered much better than items in the middle of the list
What causes the recency effect?
Information being still available in short-term memory
What evidence is there to support link between recency effect and STM?
- Asking subjects to count backwards eliminates the recency effect as it causes displacement of information from STM.
- Patient KF, who had impaired STM, did not show the recency effect.
What is the primacy effect?
Items at the beginning of a list are often remebered much better than items in the middle of the list
What causes the primacy effect?
Information passing into long-term memory, probably due to having more time for rehearsal.
What evidence is there to supprot link between LTM and the primacy effect?
- Age of subject, presentation rate… are factors that influence development of long-term memory, and affect the primacy effect but not the recency effect.
- Patient HM, who had impaired LTM, did not show the primacy effect.
What areas of the brain are involved in STM?
- Inferior frontal lobe
- Parietal lobe
What areas of the brain are involved in LTM?
Medial temporal lobe
What was Ebbinghaus’s experiment on LTM?
- Ebbinghaus taught himself lists of nonsense syllables until he could repeat the list twice without error and measured the time taken
- He then waited set intervals before re-learning the list until he could repeat it twice again
- He measured the time saved learning the list second time round compared to first
What were the results of Ebbinghaus’s experiment?
- As longer the time interval waited, the longer it took for him to relearn the list, signifying that he has forgotten more information.
- The rate of forgetting was quick in the first few hours, but slowed down as the intervals became longer. The rate of forgetting is logarithmic.
What is loss of information from LTM caused by?
Interference from newly acquired information
What are the types of interference?
- Proactive interference: Previous interference Previous learning interferes with later learning.
- Retroactive interference: Later learning interferes with previous learning.
What evidence is there for LTM interference?
- Underwood (1957): The more nonsense syllables learnt previously, the more forgetting of new syllables learnt within first 24 hours. Proactive
- Loftus & Palmer (1974): Memory from previous events can ne interfered by questions asked in post-event questioning. Retroactive
What is the function of forgetting?
It allows for important information to be easily accessible from a very large pool of information.
What are the components of LTM?
- Explicit memory: Information that needs conscious recollection of previous experience.
- Implicit memory: Information that does not need conscious recollection of previous experience.
What types of word-based memory tests can be used to test different components of LTM?
- Explicit memory:
- Recognition: Old-new distinction test
- Cued recall: Recalling all words in certain category from list
- Free recall: Recalling all words from list - Implicit memory:
- Fragment completion: Filling in partially fragmented words
- Word stem completion: Filling in word stem
- Degraded word naming: Distinguishing degraded words
What evidence is there for the existence of the explicit/implicit memory distinction?
- Patients with medial temporal lobe damage had impaired explicit memory but not implicit memory.
- Patients with occipital lobe damage and basal ganglia damage (e.g. Huntington’s disease) had impaired implicit memory but not explicit memory.
What are the components of implicit memory?
- Perceptual representation systems: Involves phenomena such as Pavlovian conditioning.
- Procedural memory: Involves the ‘muscle memory’ associated with performing complex tasks such as riding a bike or playing the piano.
How can implicit memory be tested?
- Pursuit rotor test: Patient asked to track rotating target with pointer.
- Gollin figure test: Patients shown a number of versions of the same pictures, from least to most clear. The patients are often able to identify previously seen pictures much quicker if implicit memory in tact.
What are the components of explicit memory?
- Episodic memory: Memory of specific events or episodes occurring in a particular time and space (e.g. remembering what was had for breakfast).
- Semantic memory: General knowledge about objects, people, facts and concepts independent of any temporal or spatial component (e.g. remembering what breakfast is).
What evidence is there for the existence of semantic/episodic memory distinction?
- Patients with medial temporal lobe damage seemed to have impaired episodic memory damage, but less severe semantic memory damage.
- Children with specific hippocampal damage seemed to also have impaired episodic memory but not semantic memory.
- Alzheimer patients (with impaired episodic memory) have early medial temporal lobe atrophy while patients with semantic dementia (with impaired semantic memory) have early lateral temporal lobe atrophy.
What are the stages in LTM processing?
- Encoding: Sensory information is encoded into the form it will be stored in, including forming links with pre-existing memories.
- Storage: Physical process and changes that occur in the brain neural circuitry to store information.
- Consolidation: Physical changes that occur in order to make neural changes occurring in “storage” permanent (e.g. LTP).
- Retrieval: Recalling information stored when specific cues are presented.
