principles of memory: distinctiveness

Question 1

Discuss how serial position curve data has been used as support for dual-store (STM/LTM) models of memory

Answer 1

Dual store models of memory
- ideas like the standard model of memory where long-term and short-term memory are different stores
- STM around 18 seconds with 3-7 items, can explain recency effects
- LTM any more that 22 + seconds it from LTM: can explain primacy effects

serial position curve
- Order of presentation predicts the probability of free recall of each item
- Any given item on the list can be mapped as either recalled from STM or recalled from LTM
- At the beginning of the curve: LTM (Primacy effect)
- At the end of the curve: STM (recency effect)
- In the middle of the curve: easily forgotten

when you add conditions of -
immediate long: see both effects well
immediate short: good recency effects but substantially decreased primacy effects
delay long: the recency effects completely vanish eg no short-term memory anymore, cannot rehearse cos doing distractor task
delay short: still primacy but no recency effects

Question 2

Explain the principle of (general) distinctiveness in memory

Answer 2

Distinctiveness is memory
- Unique or distinctive stimuli are easier to remember
- Overarching principle ^

Distinctive faces
- Distinctive faces are better remembered than typical faces
- Faces made more distinctive by caricaturing are better remembered

Distinctive lists
- Distinctive sequences recalled better
- Irregular pronunciation: denial, glove, comb
- Low word frequency found in English language more distinct
- Encode distinctively by pronouncing regularly
Distinctively pronounced lists remembered extremely well (+25%)

Question 3

Explain the principle of temporal distinctiveness (TD) and its main assumptions

Answer 3

Temporal distinctiveness
- Temporal distinctiveness is based on the idea that memories are—at least in part—organised in terms of their time of acquisition (psychological time)
- Memories that are encoded at the same time are more difficult to retrieve
- Therefore memories can be retrieved with reference to a time dimension (time as a retrieval cue)
- If remembered temporal position is used as a cue the success of that recall depends on temporal isolation

• Temporal distinctiveness is defined as the extent to which an item is separated from its neighbours in psychological (i.e., compressed) time
• Less distinctive items are harder to retrieve
• Due to interference from neighbours (the closer, the more interference)
• Therefore items are only distinct for a brief amount of time

Time scale invariance:
- time is log-transformed in our heads
- time is physiologically compressed In our heads.
- events from further back in time appear closer together, they are not temporally distinct therefore harder to retrieve
- Amount of recency determined by the ratio of time between the inter-presentation interval (IPI) and retention interval (RI) eg the recency of an items relative to the distance between items

Question 4

Understand how TD theory can explain serial position curves (i.e. primacy and recency effects)

Answer 4

Serial position curve Can explain recency effects
- Even if we increase the time between items we still see primacy effects, even if the items go further than 20 seconds (max STM storage in dual effect models) even in the delay condition.
- Essentially there is no effect of delay
- last few items are not scrunched up they’re easy to retrieve
- even in a delayed condition t also explains why there is less recency effects and the items become scrunched up

serial position curve primacy effects
Primacy effect
- If more distant neighbours are also important, then this “edge effect” benefits more than just one item
- The further away from the edge we move the more interference from neighbouring items
- Therefore memory of items in the middle will be the worst
- Time is a bad retrieval cue for early items
- In this case something like and n emotional cue would be better

• So for patients who have access to LTM but not STM could be explained that they have lost access to that temporal dimension and instead can use emotional cues to remember things

Question 5

Cite a piece of evidence that TD theory but not dual-store theory can handle

Answer 5

recency effects with increased IPI
- increasing the inter-presentation interval
- instead of 1 second between each stimulus there are 5 seconds and there is still a 30second delay
- we see recency effects return looks like the immediate recall condition again as in psychological time we are seeing the same pattern
- duel store can not explain this as it goes beyond the scope of STM so we should not see recency effects

• Amount of recency determined by the ratio of time between the inter-presentation interval (IPI) and retention interval (RI) eg the recency of an items relative to the distance between items

Question 6

Understand what is meant by the time-scale invariance of TD

Answer 6

• the recency of an item relative to the distance between items
• Amount of recency determined by the ratio of time between the inter-presentation interval (IPI) and retention interval (RI)

therefore we see recency effects if
- if last item is recent and they are all close together
- if last item is distant and they are all widely separated in time

Question 7

Discuss the implications of TD theory

Answer 7

effects of post-study rest
- Rest after study can lead to astonishing improvement in recall, especially in memory-impaired patients (Della Sala, Cowan et al., 2005)
- Increases temporal distinctiveness and prevents interference

Beneficial Effects of sleep on Memory
- Most likely a combination of temporal distinctiveness and neural ‘consolidation’ mechanism during slow-wave sleep (Born et al., 2006)
- Synaptic consolidation is a Presumed neural process (synaptic transmission enhancement and protein synthesis), stabilizing newly created memory traces during periods of mental inactivity. The reactivation of newly established patterns and connections

Rest before study can also improve memory:
- predicted only by TD theory (Ecker et al., 2015; McGhee et al., 2020)
- Maybe you can insulate something you’ve learnt by resting before and after

Question 8

limits of temporal distinctiveness

Answer 8

• Continuous input of information is not preserved as continuous
• People spontaneously parse ongoing events into episodes
• Memory is better for information from the current episode
• Crossing event boundaries impairs memory

Radvansky & Copeland (2006)
- “Walking through doorways causes forgetting”
- People picked up, carried, and put down various objects in a virtual environment
- Memory for objects currently carried or just put down was better while still in the same room
- Independent of time or temporal distinctiveness

Ezzyat & Davachi (2011)
- Reading of narrative text
- Boundary markers such as “After a while,…” leads to parsing into episodes
- Given a sentence, retrieval of the subsequent sentence better within such episodes than across

TD cannot account for this difference in memory performance across conditions where the boundary marker is different but the TD is the same