Outline the Multi Store Model
- Information from the environment passes through sensory register to sensory memory
- If you pay attention to the sensory memory it passes through to short term memory (acoustic encoding)
- Elaborative rehearsal passes it though to long term memory (semantic encoding)
-All ca be lost by displacement or decay
Short Term Memory Capacity?
- Miller (1956): the STM can hold ‘the magic number seven, plus or minus two’
- Duration – 18-30 seconds
Short Term Memory Duration?
-Peterson & Peterson (1959) got students to recall combinations of 3 letters (trigrams), after longer and longer intervals.
- Participants shown trigrams and then distracted, were able to recall about 90% after 3 seconds and only 5% after 18 seconds.
- This shows that the duration for which STM can retain info is temporary and will be lost unless it is rehearsed.
Long Term Memory Encoding?
- Baddeley (1966) presented lists of 10 short words one at a time.
- Found that after 20 mins, they did poorly on the semantically similar words.
- This suggests that we encode LTMs according to what they mean – so we get similar-meaning things confused!
Strength of MSM -case studies
- Clive Wearing and HM
- The MSM explains their disability as a failure to rehearse information, preventing them from encoding information in LTM.
Strength of MSM -researchers
- Glanzer and Cunitz conducted an experiment where participants recalled a list of 20 words.
- They were interested in seeing if the position of the words had any effect on whether participants can recall them
- Participants recalled more words from the beginning (primacy effect) and the end (recency effect) of the word list.
- The words in the middle were poorly recalled.
- The words in the beginning were rehearsed more and had been linked to the long term store.
- The words in the end occupied the capacity of the short term store, displacing the words in the middle.
-This research provides evidence that the short term store and the long term store are separate and process memories differently.
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Weakness of MSM
- It does not account for memories which do not require rehearsal eg flashbulb memory.
- This directly contradicts the Multi-store model which says that information must be rehearsed in order to be transferred to the LTM
- Its description of STM may be too simplistic.
- Dual task experiments show that we perform poorly when trying to complete two similar tasks at the same time (eg two verbal tasks), but we perform well when doing two tasks of a different nature (eg on verbal and one visual).
- This dual capacity cannot be explained by MSM as it suggests that the limited capacity of STM is not dependent on the type of information.
Therefore Working Memory may be a better explanation as it explains dual task performance and is seen as a more dynamic model of STM.
Outline the Working Memory Model
- Central Executive: briefly process different forms of information.
- It focuses, divides and switches our limited attention.
- It monitors incoming data, makes decisions and allocates slave subsystems to tasks.
- Has a very limited processing capacity and does not store information
- Phonological Loop: Auditory short term memory
- Can store and repeat verbal information for a limited period of time.
- Two subcomponents:
1) The articulatory process, e.g. remembering a phone number by repeating it in your head.
2) The phonological store, e.g. you will be able to hold an auditory memory of your teachers last sentence when she dictates notes to you in class.
-Visuo-spatial sketchpad: Visual and spatial short term memory – temporarily stores visual and/or spatial information.
- Episodic buffer:
- Temporary store that integrates the acoustic, visual and spatial information processed by other subsystems.
- It also maintains a sense of time sequencing, basically recording events (episodes) that are happening.
Outline Tulving’s Long Term Memory Theory
split into 4 sections
- Episodic memory: These are autobiographical
- Semantic memory: Facts/knowledge of something, but you do not recall how you gained the knowledge. Like a mental encyclopedia.
1) Nature of memory
2) Time referencing
3) Spatial Referencing
4) Retrieval
Strength of WMM
- There is evidence from brain damaged patients which support the idea of separate short-term memory stores.
- KF suffered brain damage after a motorbike accident and this left him unable to form or recall memories of personal events in his life (episodic). However, he was able to recall factual information (semantic).
- This case study supports the idea of separate long-term stores, but also indicates that these may be stored in different regions of the brain giving avenues for further research.
Weakness of WMM
- Other case studies such as that of HM and Clive wearing, demonstrate a weakness of the model.
- In both of these cases they were unable to recall long-term memories from episodic storage, however they were able to remember how to perform tasks, for example Clive Wearing could still play the piano.
- Therefore, there must be a further long-term store for remembering practiced skills. In a reformulation of his theory, Tulving 1985, suggested we have a separate procedural memory which contains memory for skills and abilities such as learning grammar or riding a bike.
What is Reconstructive memory and what does it consist of?
-Bartlett considers memory as reconstructive, not split into stores. It is based from previous knowledge and experiences
- A schema is an organised package of information that stores our knowledge about the world
- A schema is made up of all our previous experiences and expectations about an event
- Schemas are good: These preexisting frameworks of knowledge can be used to predict things and make short cuts when encountering new situations
- Schemas are bad: Can lead to prejudice, e.g. You have schemas for certain groups of people, which can lead to you to become prejudiced against them
Study for Reconstructive memory
- The aim of his study was to see if cultural background and unfamiliarity with a text would lead to distortion of memory when the story was recalled.
- Bartlett had 20 British participants learn a Native American story named “The War of Ghosts”.
- The participants read the story at their normal reading speed, then made their first reproduction 15 minutes after.
- This was then repeated over several time intervals, few hours, days, weeks, even years…
- This process of repeating the story over time is known as serial reproduction.
- It was culturally unfamiliar to the participants which would make it easier for him to examine the transformations.
- It lacked any rational story order.
- The dramatic nature of the story would encourage visual imaging.
3 Patterns of distortion (Bartlett)
-The story was changed in 3 ways:
Confabulation: The story became more consistent with the participants’ own cultural expectations. E.g. objects within the story were made more familiar – ‘canoe’ was changed to ‘boat’, ‘hunting seals’ changed to ‘fishing’.
- Levelling: The story also became shorter with each retelling as participants omitted information which was seen as not important. (330 words – 180 words) E.g. Many participants did not grasp the role of the ghosts in the story, so simply omitted to mention them.
- Rationalisation: Participants also tended to change the order of the story in order to make sense of it using terms more familiar to the culture of the participants.
Strength of Bartlett’s study
- In his “War of Ghosts” study participants altered the story upon each recall, omitting and rationalising the information.
- Therefore this illustrates how we have SUBJECTIVE MEMORY
Weakness of Bartlett’s study
-it is based on evidence which can be criticised as use of the ‘War of the Ghosts’ story has little relevance in everyday life.
Outline Classic Study
Baddeley
-To find out if LTM is encoded acoustically (based on sound) or semantically (based on meaning).
- There were 72 volunteer participants, a mixture of men and women recruited from Cambridge University, so mostly students.
- List A – Contained 10 acoustically similar words
- List B – Contained 10 acoustically dissimilar words
- List C – Contained 10 semantically similar words
- List D – Contained 10 semantically dissimilar words
- Each list was presented via projector at a rate of one word every three seconds.
- The participants were required to complete six tasks involving memory for digits (interference task to prevent rehearsal). They were given 8 random numbers to write down three times.
- After each interference task participants had to recall the words in the correct order. This was repeated over 4 learning trials (steps 1-3, to measures STM).
- Participants were then given an interference task for 15 minutes and then a surprise 5th test (to test LTM) where they had to recall the words in the correct sequence again.
- When they had to recall immediately (STM recall), they tended to perform worse with acoustically similar words.
- When they had to recall after 20 minutes (LTM recall), they tended to perform worse with semantically similar words.
- This suggests that information is coded acoustically in STM and semantically in LTM.
Weakness of Classic Study
- Baddeley
- A limitation of the study is population validity
- The participant were all volunteer students from a research unit at the University of Cambridge. The participants are likely to be much more highly educated and academic than the general population. They are also more likely to be young as they are university students.
- Therefore the study has low population validity, as the sample is very different from the general population, so the findings that we encode semantically in our LTM cannot be applied to the wider population, to help us understand how memory works.
Strength of Classic Study
- Baddeley
- The study was scientific in that it was conducted in a controlled laboratory environment with a standardised procedure.
- Due to the highly controlled nature of the experiment, Baddeley can also establish cause and effect relationship between the independent variable (semantic or acoustic word list similarity), and the dependent variable (long-term memory).
- Therefore the study can be regarded as replicable and the reliability of the results can be established
- Another strength is that Baddeley’s results can be applied to the wider world, specifically in education.
His finding that we encode semantically in our LTM has enabled teachers and other professionals to promote the best learning strategies to improve memory.
Applying Baddeley’s findings that LTM requires semantic encoding has led to the introduction of memory improvement strategies such as mind maps.
Outline Contemporary Study
- Schmolk et al
- Find out if there was a link between damage to the temporal cortex of the brain and performance on tests of semantic memory in people with amnesia.
- Also to see if there was anything unique about patient HM.
-8 controls healthy males, matched on age and education to experimental group.
-6 amnesic participants (5 male, 1 female) - 2 HF (damage limited to hippocampus), 3 MTL+ (large lesions to medial temporal lobe), and then patient HM (hippocampal and some MTL damage).
They used MRI scanners to assess the damage
-Each participant completed 9 tasks testing semantic memory, e.g.
-48 drawings sorted into 24 living items (animals) and 24 non-living items (objects), sort into groups.
Define an item from its name, define an item from its picture.
-Answers were recorded and 14 people checked responses
- HF group did just as good if not better than control
- MTL group did the worst in all tasks
- HM did better than MTL but worse than control and HF group
- Therefore the hippocampus is not involved in semantic knowledge
- Semantic memory issues are associated with levels of damage to the medial temporal cortex
Strength of Contemporary Study
- Schmolk et al
- This study used a control group of healthy participants that were ‘matched’ with the patients who had brain damage. As the control group achieved more or less 100% success in the tests, this supports the claim that the tests measured ‘typical’ functioning
- This is a strength because it means we can be reasonably sure that the different scores on the tests were caused by the lesions (damage) in certain parts of the brain, not by individual differences such as age or intelligence.
-Real Life applications:
-It provides a detailed map for neurosurgeons to use when removing a brain tumour so they can avoid areas involved in crucial cognitive functions (not repeat HM surgery in 1953).
Therefore this research has value beyond the theoretical understanding of semantic memory that it provides, as it helps us understand the risks of brain surgery and the side-effects of brain damage
Weakness of contemporary Study
- Schmolk et al
- Schmolck used a small sample – only 3 patients with MTL+ damage, 2 with hippocampus damage (HF) and HM. He compared the brain injured participants to the control group.
- This is a weakness because the case studies of individuals have relatively rare brain injuries. Samples this small are easily distorted by anomalies/outliers and we don’t know about the cognitive functioning of patients before they experienced an unexpected brain injury.
- This makes valid comparisons impossible, so we cannot generalise how semantic knowledge and the medial temporal cortex are related and cannot be sure that other patients with brain damage would show the same pattern of results.
-Participants were asked to complete a variety of tests including naming and categorising drawings on cards in a lab setting.
This is a weakness because these artificial tests conducted in a laboratory environment do not represent how our memory works in everyday life, naming and categorising drawings on cards is more like a game or a puzzle than the sort of semantic memory you need in real life.
-Therefore it could be argued that the measures in this study may not capture ‘the whole picture’ and therefore may not be valid, so this study cannot be used to explain the effect of brain damage on semantic knowledge.
Individual Differences and Developmental Memory Study
Individual:
-Schemas
-Everyone’s experiences in life is different, as such the schemas we form are also different.
-Schemas inform the way we interpret things
-As we rely on schemas to reconstruct our memories according to Bartlett, the way we encode memories differs between individuals
-Memory Ability
-People have dfferent memory capacities
-Palombo et al (2012) tested the autobiographical memory components of semantic and episodic memories in 598 volunteers.
-She found that individuals who score high or low in episodic memory also scores high or low in semantic memories.
-Men also tended to score higher in spatial memory
-Thus demonstrating that people have overall “good” or “poor” memories individually
-Developmetal:
-Alzheimer’s is a progressive, degenerative neurological disorder which affect 1 in 20 people
-Characterised by progressive memory loss, concentration loss and confusion
-Central executive is affected, working memory processes impacted. Dual tasks are particularly difficult. Complex tasks become hard to coordinate and visuospatial processing becomes impaired
-Baddeley et al (2001): Conducted a series of tasks on individuals with Alzheimer’s disease and controls.
- Involving looking for the letter “Z” among easy and difficult distractor letters (ease based on how similar the distractor letters were to the letter).
- A dual task procedure was also utilised. (also processing auditory information)
- People with Alzheimer’s performed worse in the difficult distractor tasks and were also very impaired on dual task procedures.
- This demonstrates Alzheimer’s affects dual attentional memory tasks
HM Case Study
-Was involved in a bicycle accident, which lead him to develop severe epileptic fits several times a day
-Had a neurosurgeon remove parts of his brain to reduce these episodes
-Dr. Scoville removed the hippocampus in his brain.
-This removal was confirmed with an MRI scan
-HM now suffered from retrograde amnesia (cannot access old memories from the past 10 years) and anterograde amnesia (cannot form new memories)
-Procedural memories for HM remained intact, for example he was able to develop his skill in drawing a star within two concentric stars when looking into a mirror
-His short term memory has the same duration as controls
-His intelligence and personality was unchanged according to reports from childhood friends
-No new memories can be stored in STM
-Shows that LTM and STM are separate. LTM functional, but STM damaged
-Showed that to encode information from STM to LTM, the hippocampus needs to be used. As he does not have them, he cannot form new LTM
