AQA A-LEVEL PSYCHOLOGY REVISION NOTES: MEMORY

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PSYCHOLOGY AQA A-LEVEL UNIT 1 (7182/1)

THE SYLLABUS

MODELS OF MEMORY; SHORT-TERM MEMORY AND LONG-TERM MEMORY

• The multi-store model of memory: sensory register, short-term memory and long-term memory. Features of each store: coding, capacity and duration
• Types of long-term memory: episodic, semantic, procedural
• The working memory model: central executive, phonological loop, visuo-spatial sketchpad and episodic buffer. Features of the model: coding and capacity

 FORGETTING

• Explanations for forgetting: proactive and retroactive interference and retrieval failure due to absence of cues

 EYEWITNESS TESTIMONY

• Factors affecting the accuracy of eyewitness testimony: misleading information, including leading questions, post-event discussion, and anxiety
• Improving the accuracy of eyewitness testimony, including the use of the cognitive interview

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INTRODUCTION

Cognitive Psychology studies mental processes and abilities such as thought, language, perception, decision-making, etc. Memory is the cognitive ability which underlies much of what makes us human. It allows complex thought, language, learning, prediction and anticipation of the future, reflection on past events, etc.

As the neurophysiology (biological structure and function of the brain) of memory is extremely complex, cognitive psychologists generally use theoretical models to understand the processes underlying memory. There is a basic division between short-term memory (STM) and long-term memory (LTM) in terms of these different stores’ capacity, duration and encoding (in what format a memory trace is stored – visually, acoustically or semantically).

The Multi-Store Model examines how material is passed from short-term memory to long-term memory, and the Working Memory Model focuses on the different component parts of short-term memory.

The study of long-term memory reveals that memories relating to what we know about the world, ourselves and how to do things seem to be stored and accessed in different ways, and that forgetting in long-term memory may be the result of interference from competing memories or a failure to locate a particular memory due to a lack of cues (hints or reminders that aid recall).

An important practical application of memory research relates to the accuracy of people’s memories of crimes they may have witnessed (eye-witness testimony), and crime investigators use cognitive interview techniques derived from psychological findings to improve the accuracy and detail of witnesses’ memories.

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DEFINITIONS & STUDIES – STM, LTM & DURATION, CAPACITY & ENCODING (Psychology A-level revision)

• Short-term memory (STM) refers to recall of information from the very recent past: e.g. remembering a telephone number or items on a shopping list.
• Long-term memory (LTM) refers to all memories which are more permanently stored: e.g. your own telephone number, names of old class mates, etc. 

• Duration refers to the length for which memories can be stored.
• Capacity refers to the amount of information that can be stored.
• Encoding (or Coding) refers to how a memory is processed and This could be visually (as an image), acoustically (what the word sounds like) or semantically (to do with the meaning of the memory). For example, we may remember ‘dog’ by visualizing a dog we know, remembering the sound of the word ‘dog’, or recall a memory of being bitten by a dog when we were young.
• Retrieval refers to one’s ability to recall a memory.

In summary, basic findings regarding memory are

	SHORT-TERM MEMORY	LONG TERM MEMORY
DURATION	Approx. 18-30 seconds	Hours/Days/Years
CAPACITY	7 (+/- 2) chunks of information	Potentially unlimited
ENCODING	Acoustic	Semantic

 A STUDY INTO DURATION OF SHORT-TERM MEMORY

Peterson and Peterson (‘59)

• Conducted a study into the duration of STM using 24 students.
• Subjects were given a nonsense trigram (three random, non-meaningful letters: e.g. HXT rather than JAR, to prevent words being ‘meaningful and thus better remembered) and then given a number from which they had to count backwards from in 3s or 4s to stop them rehearsing the trigram.
• After either 3, 6, 9, 12, 15 or 18 seconds they were told to stop counting and remember the trigram. The researchers recorded the % of trigrams correctly recalled for each time interval.
• After 3 seconds, participants remembered about 90% of the time. After 18 seconds, this fell to only 2%.
• This suggests that the duration of STM is 18 seconds at most when rehearsal is prevented.

A STUDY INTO CAPACITY OF SHORT-TERM MEMORY

Miller (‘56)

• Reviewed a number of studies where participants were asked to remember the number of dots flashed up onto a screen, musical notes, digits, letters or words.
• All studies found that STM’s capacity was 7 (+/-2) items.
• More can be remembered by chunking information together, e.g. remembering 5, 2, 7, 4, 6, 1 as 52, 74, 61. Equally, we can remember 5 words as well as we can 5 letters, although the larger the chunk, the less chunks can be remembered.

A STUDY INTO ENCODING IN MEMORY

Baddeley (‘66)

• Gave participants lists of words that were either
  • Acoustically similar – cat, cab, can
  • Acoustically dissimilar – pit, few, cow
  • Semantically similar – great, large, big
  • Semantically dissimilar – good, wide, thin

They were then asked to recall these words immediately.

• Words that sounded similar were by far the hardest to remember suggesting that STM stores information acoustically: e. subjects confused the acoustically similar words with each other.
• He then presented lists of words in one of the 4 categories above and tested recall after 20 minutes. This time, words that were similar in meaning had the poorest recall. Thus, he concluded that LTM mainly codes memories

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THE MULTI-STORE MODEL OF MEMORY (MSM) (A-level Psychology revision)

Atkinson & Shiffrin (‘68)

Sensory store/register

• Environmental stimuli from the senses is received by the sensory memory (SM), where it remains for split seconds (Duration: approx. 250 milliseconds, Capacity: unlimited).
• If attention is paid to any of this information data is transferred to short-term memory (STM) otherwise it immediately decays and is forgotten.
• (The sensory memory does not have a particular form of encoding – rather encoding depends on which mode (sight, sound, touch, etc.) that it arrived in – therefore, its encoding is referred to as modality specific.

Short-term memory

• Information will decay from the STM very quickly (within 18-30 seconds) if it is not subject to maintenance rehearsal: i.e. repeated over and over again.
• As STM has a limited capacity, it might become displaced by other competing information.

Long-term memory

• Rehearsal of information will allow it to be transferred to LTM – the more it is rehearsed the better it will be remembered.
• Once in the LTM memories can be retrieved.

EVALUATION - strengths

Research evidence supporting the MSM

Milner (‘57)

• HM (the participant in a case study) had his hippocampus removed in an operation to reduce his epilepsy.
• After the operation he could remember things he had just been told suggesting that his STM was intact, but he could not transfer this information to the LTM: for example, he would read the same magazine repeatedly and was unable to recognise the psychologists who treated him.
• He had LTMs from 10 years before his surgery but had lost LTMs for the 10 years up until his surgery.
• This provides evidence for the MSMs claim that STM and LTM are 2 separate and distinct stores.

Glanzer (’66) – The Primacy-Recency Effect

• Found that when subjects were presented with a list of words and then asked to recall these words they tended to remember ones from the beginning (primacy) and from the end (recency). The primacy effect occurs as words have been transferred to LTM through rehearsal; the recency effect occurs as the last words on the list are recalled from STM before they decay.
• By adding a 30m second delay before participants recalled words memory of later words on the list fell dramatically as they decayed from STM.
• This provides evidence for the MSMs claim that STM and LTM are 2 separate and distinct stores.
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Research evidence contradicting the MSM

• The MSM is now considered a rather basic analysis which oversimplifies memory structures and processes: in particular that the structures of STM and LTM each operate in a single, uniform fashion. The Working Memory Model provides evidence that STM is composed of several different stores which handle visual and acoustic information differently and separately. Research into LTM also indicates we have separate memory stores for memories about our knowledge (semantic), our personal history (episodic) and our ability to do things (procedural).

Shallice and Warrington (‘70)

• KF suffered brain damage which resulted in difficulty dealing with verbal information in STM, but a normal ability to process visual information in STM.
• This suggests that STM is not a single store as the model proposes and implies (as the Working Memory Model does) that STM is composed of a number of separate stores.

Craik and Tulving’s Levels of Processing Model argues that the strength of long term memories is not simply determined by the amount of rehearsal that takes place but rather the type of rehearsal that takes place. They conducted a study where participants were given a list of nouns and then asked a question about each word.

1. Is the word printed in capital letters? – shallow processing (what the word looks like).
2. Does the word rhyme with ‘train’? – phonemic processing (what the word sounds like).
3. Is the word a type of fruit? – deep semantic processing (the meaning of the word).

Words from the 3^rd condition were recalled most easily suggesting that elaborative rehearsal (which involves deeper analysis/processing) results in a stronger memory trace: i.e. we will remember material that we find more interesting, relevant and meaningful for us.

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TYPES OF LONG-TERM MEMORY (AQA A-level Psychology revision)

 

EPISODIC MEMORY

LT memories of your personal experiences and the time, place, context and emotions surrounding events which happened in the past: e.g. your 1^st day at school. Episodic memories are explicit: i.e. require conscious effort.

SEMANTIC MEMORY

LT memory of knowledge of factual information which is not personal to you but is shared by a number of people: e.g. the capital of Britain is London. Semantic memories include factual knowledge but also knowledge relating to the properties of objects (e.g. chilli is hot), rules of social behaviour, and abstract concepts such as maths and physics. Semantic memories are explicit: i.e. require conscious effort.

PROCEDURAL MEMORY

Memories of how to do things: e.g. ride a bicycle. These are acquired through learning, repetition and practice and are often implicit - unconscious and automatic (i.e. we don’t need to consciously think about how to swim).

EVALUATION

EVIDENCE FROM BRAIN SCANS

• Research with brain scans has found that different brain areas are associated with the 3 types of LT memory.
  • Episodic memories occur in the hippocampus and other portions of the temporal lobe and the frontal lobe.
  • Semantic memory is associated with the temporal lobe.
  • Procedural memories occur in the cerebellum, basal ganglia and limbic system. The cerebellum is also associated with motor skills: i.e. skills to do with movement.

DIFFERENCE BETWEEN PROCEDURAL AND DECLARATIVE MEMORIES

With the case study of HM we had previously learnt that after surgery his ability to form new LT memories was interfered with. This is a simplification: in fact, he could form new procedural memories in his LTM but could not form new episodic or semantic ones. This provides evidence for the claim that LTM is not a single store but composed of different stores handling different types of information.

DIFFERENCE BETWEEN EPISODIC AND SEMANTIC MEMORIES

It can be argued that the ability to form new episodic memories is the key to allowing us to form new semantic memories; i.e. our memory of events allows us to form memories of new facts. For example, I went to the art gallery (episodic) and learned about Picasso (semantic).

Researchers studying Alzheimer’s patients have found that some patients keep the ability to form new episodic memories but not new semantic ones which provides evidence for this argument. This is an example of dissociation – a separation between 2 abilities.

However, this doesn’t prove that episodic and semantic memories are entirely separate. Also, there are cases where the reverse is true – Alzheimer’s patients who can form new semantic memories but not new episodic ones.

PRIMING – A 4^TH KIND OF LTM

Priming is concerned with how implicit memories affect the responses a person makes: for example, if someone is told the word yellow then asked to name a fruit they are likely to answer ‘banana’ (yellow + fruit). This association is automatic and unconscious. Research has shown that priming is controlled by a different area of the brain from the temporal brain area which controls explicit memories. Some researchers have, therefore, suggested the existence of a 4^th type of LTM – the ‘perceptual-representation system’ (PRS) which is concerned with recognising and forming associations between particular stimuli.

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THE WORKING MEMORY MODEL (WMM) (AQA A-level Psychology revision guide)

Baddeley & Hitch (’74)

The WMM takes a more sophisticated view of STM as being composed of various separate but inter-related stores where different types of operations are performed on incoming information by different parts of the STM before being passed onto the LTM or forgotten.

B&H proposed that the STM is composed of

The Central Executive

• Information arrives from the senses or from the long-term memory and the Central Executive decides which of the ‘slave systems’ (below) are needed to deal with it.
• It deals with a number of tasks, e.g. attention, switching attention between tasks and other higher mental processes such as decision-making and problem-solving.

The Phonological Loop

• Deals with auditory/acoustic information and has a limited capacity.
• Is subdivided into:
  • The Phonological Store (inner ear) – retains words we hear for 1–2 seconds.
  • The Articulatory Process (inner voice) – retains information we hear or see by silently repeating it (looped) like an inner voice.

Visuo-Spatial Sketchpad

• The inner eye - holds visual (how things look) and spatial (the relationship between things) information.
• Manipulates mental imagery, perceives movement and recognises patterns.

Episodic Buffer

• A temporary storage area which combines and brings together information received from the phonological loop, the visuo-spatial sketchpad and the central executive.

EVALUATION - strengths

The WMM is well supported by research evidence.

Baddeley and Hitch (‘74)

• Participants were given digits to rehearse while carrying out a verbal reasoning task. They performed well on both tasks.
• This suggests that working memory consists of several different components that can work independently of one another and so handle more than one task at a time.

Baddeley (‘73)

• Participants followed a spot of light moving round a circular path whilst either performing a visual task or a verbal
• Participants performed poorly at the visual task but not at the verbal task. This is because the visuo-spatial sketchpad became overloaded by having to deal with 2 visual tasks at once whereas performing a visual and a verbal task used 2 separate stores. This suggests that STM has a different visual and auditory store.

The model is also supported by research with brain damaged patients.

• KF - Had difficulty dealing with verbal information in STM, but a normal ability to process visual information in STM.
• SC – Had generally good learning abilities with the exception of being unable to learn word pairs that were presented out loud: i.e. had a problem with the phonological store only whilst other parts of his STM worked normally.

EVALUATION - weaknesses

We know little about the role of the Central Executive and what has been written about it is vague and difficult to test. Critics argue that the notion of a single Central Executive is wrong and there are probably several components. For example, Eslinger studied EVR who, after an operation on a cerebral tumour, performed well on reasoning tasks but had poor decision-making skills. The Central Executive is supposed to manage both of these areas. This case study indicates otherwise.

 The above studies suggest separate stores for verbal and visual information as proposed by the WMM. However, as they are case studies based on single participants there is low population validity and findings should be generalised with caution.

 The model also tends to ignore how STMs are passed on to LTM.

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FORGETTING (A-level Psychology resources)

EXPLANATIONS FOR FORGETTING: PROACTIVE AND RETROACTIVE INTERFERENCE AND RETRIEVAL FAILURE DUE TO ABSENCE OF CUES

PROACTIVE AND RETROACTIVE INTERFERENCE

Interference refers to information heard either before or after another piece of information causing poorer recall of this information....

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