Cognitive neuroscience of memory

Question 1

What are the stages in memory processing?

Answer 1

1. Encoding of information into memory
2. Storage of information into memory systems
3. Retrieval of information from memory

Question 2

What is the multi-store model for memory?

Answer 2

1. Sensory memory: Brief store of sensory information that does not need to be attended to.
2. Short-term store: Holds information for longer period of time that requires attention (limited capacity).
3. Long-term store: Information from short-terms store passes into this and can be held for indefinite amount of time (virtually unlimited capacity).

Question 3

Who proposed the multi-store model?

Answer 3

Atkinson & Shiffrin (1968)

Question 4

What type of information is stored in sensory stores?

Answer 4

• All information detected by sensory systems.
• Stores are independent of attention.

Question 5

What are the types of sensory stores?

Answer 5

1. Iconic memory: Visual information
2. Echoic memory: Auditory information

Question 6

What was the experiment on iconic memory performed by Sperling?

Answer 6

• 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.

Question 7

What is the duration of iconic memory?

Answer 7

~1 second

Question 8

What was the experiment on echoic memory performed by Treisman?

Answer 8

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.

Question 9

What is the duration of echoic memory?

Answer 9

~2 seconds

Question 10

What is short-term memory?

Answer 10

STM is used to hold information ‘in mind’ for short periods of time while performing complex tasks.

Question 11

What is the capacity of short-term memory?

Answer 11

7 ± 2 chunks

Question 12

What is the duration of short-term memory?

Answer 12

A few seconds

Question 13

What is loss of information from short-term memory mediated by?

Answer 13

Displacement by interference, with no contribution from temporal decay

Question 14

What was the experiment on short term memory performed by Waugh & Norman?

Answer 14

1. Subjects were presented with a string of 16 numbers under 2 conditions:
   - Slowly with long intervals between numbers
   - Quickly with short intervals between numbers
2. Subjects were then asked to count backwards and then recall the numbers in digit string.

Question 15

What was the purpose of the Waugh & Norman experiment?

Answer 15

Showed that loss of information from short term memory was due to displacement, not decay.

Question 16

What are the criticisms of the multi-store model for short-term memory?

Answer 16

1. 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.
2. 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.

Question 17

What is the working memory?

Answer 17

1. Central executive: Modality-free and is responsible for selecting information from the 2 associated stores.
2. Phonological loop: Stores auditory information (and auditory representation of other forms of information).
3. Visuo-spatial sketchpad: Stores visual and spatial information.

Question 18

What is the phonological similarity effect?

Answer 18

Subjects were much better at remembering phonologically distinct words than phonologically similar words, implying that this information was stored in an auditory-dependent manner.

Question 19

What is the explanation for the phonological similarity effect?

Answer 19

There is confusion between the similar sounding words in the phonological store, making recall much more difficult.

Question 20

What is the word length effect?

Answer 20

• 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).

Question 21

What is the explanation for the work length effect?

Answer 21

• 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.

Question 22

What are the components of the visuo-spatial sketchpad?

Answer 22

1. Visual cache: All visual information regarding form and colour pass into this first. Information here can be displaced by new visual information.
2. Inner scribe: Visual information passes into this component where it can be rehearsed. This component also used for spatial processing.

Question 23

What are the similarities between the phonological loop and the visuo-spatial sketchpad?

Answer 23

Phonological loop = Visual cache

Articulatory control process = Inner scribe

Question 24

What is the recency effect?

Answer 24

Items at the end of a list are often remebered much better than items in the middle of the list

Question 25

What causes the recency effect?

Answer 25

Information being still available in short-term memory

Question 26

What evidence is there to support link between recency effect and STM?

Answer 26

1. Asking subjects to count backwards eliminates the recency effect as it causes displacement of information from STM.
2. Patient KF, who had impaired STM, did not show the recency effect.

Question 27

What is the primacy effect?

Answer 27

Items at the beginning of a list are often remebered much better than items in the middle of the list

Question 28

What causes the primacy effect?

Answer 28

Information passing into long-term memory, probably due to having more time for rehearsal.

Question 29

What evidence is there to supprot link between LTM and the primacy effect?

Answer 29

1. Age of subject, presentation rate… are factors that influence development of long-term memory, and affect the primacy effect but not the recency effect.
2. Patient HM, who had impaired LTM, did not show the primacy effect.

Question 30

What areas of the brain are involved in STM?

Answer 30

• Inferior frontal lobe
• Parietal lobe

Question 31

What areas of the brain are involved in LTM?

Answer 31

Medial temporal lobe

Question 32

What was Ebbinghaus’s experiment on LTM?

Answer 32

1. Ebbinghaus taught himself lists of nonsense syllables until he could repeat the list twice without error and measured the time taken
2. He then waited set intervals before re-learning the list until he could repeat it twice again
3. He measured the time saved learning the list second time round compared to first

Question 33

What were the results of Ebbinghaus’s experiment?

Answer 33

1. As longer the time interval waited, the longer it took for him to relearn the list, signifying that he has forgotten more information.
2. 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.

Question 34

What is loss of information from LTM caused by?

Answer 34

Interference from newly acquired information

Question 35

What are the types of interference?

Answer 35

1. Proactive interference: Previous interference Previous learning interferes with later learning.
2. Retroactive interference: Later learning interferes with previous learning.

Question 36

What evidence is there for LTM interference?

Answer 36

1. Underwood (1957): The more nonsense syllables learnt previously, the more forgetting of new syllables learnt within first 24 hours. Proactive
2. Loftus & Palmer (1974): Memory from previous events can ne interfered by questions asked in post-event questioning. Retroactive

Question 37

What is the function of forgetting?

Answer 37

It allows for important information to be easily accessible from a very large pool of information.

Question 38

What are the components of LTM?

Answer 38

1. Explicit memory: Information that needs conscious recollection of previous experience.
2. Implicit memory: Information that does not need conscious recollection of previous experience.

Question 39

What types of word-based memory tests can be used to test different components of LTM?

Answer 39

1. Explicit memory:
   - Recognition: Old-new distinction test
   - Cued recall: Recalling all words in certain category from list
   - Free recall: Recalling all words from list
2. Implicit memory:
   - Fragment completion: Filling in partially fragmented words
   - Word stem completion: Filling in word stem
   - Degraded word naming: Distinguishing degraded words

Question 40

What evidence is there for the existence of the explicit/implicit memory distinction?

Answer 40

1. Patients with medial temporal lobe damage had impaired explicit memory but not implicit memory.
2. Patients with occipital lobe damage and basal ganglia damage (e.g. Huntington’s disease) had impaired implicit memory but not explicit memory.

Question 41

What are the components of implicit memory?

Answer 41

1. Perceptual representation systems: Involves phenomena such as Pavlovian conditioning.
2. Procedural memory: Involves the ‘muscle memory’ associated with performing complex tasks such as riding a bike or playing the piano.

Question 42

How can implicit memory be tested?

Answer 42

1. Pursuit rotor test: Patient asked to track rotating target with pointer.
2. 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.

Question 43

What are the components of explicit memory?

Answer 43

1. Episodic memory: Memory of specific events or episodes occurring in a particular time and space (e.g. remembering what was had for breakfast).
2. Semantic memory: General knowledge about objects, people, facts and concepts independent of any temporal or spatial component (e.g. remembering what breakfast is).

Question 44

What evidence is there for the existence of semantic/episodic memory distinction?

Answer 44

1. Patients with medial temporal lobe damage seemed to have impaired episodic memory damage, but less severe semantic memory damage.
2. Children with specific hippocampal damage seemed to also have impaired episodic memory but not semantic memory.
3. 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.

Question 45

What are the stages in LTM processing?

Answer 45

1. Encoding: Sensory information is encoded into the form it will be stored in, including forming links with pre-existing memories.
2. Storage: Physical process and changes that occur in the brain neural circuitry to store information.
3. Consolidation: Physical changes that occur in order to make neural changes occurring in “storage” permanent (e.g. LTP).
4. Retrieval: Recalling information stored when specific cues are presented.