Memory

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Definition of Coding

Changing the format of information for use in memory (also reffered to as enconding)

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Definition of Capacity

The amount of information that can be held in memory

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Definition of Duration

The length of time information remains in memory. 

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The Multi-store Model of Memory

It was Proposed by Atkinson and Shiffrin (1968)

They saw it as a flow system dividd into a series of interacting memory store. Each store has a different purpose, an each varies in terms of coding, capacity and duration.

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Definition of Sensory register

A store of sensory information that lsts no more than a few seconds.

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Iconic Register

Refers to our memory for visual information. (You can view an Icon)

Cartoons are made up of a series of photos, we don't see th blank spaces between them

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Echoic Memory

Is the sensory register for auditory information. Research by Darwen et al (1972). The length of time information is stored in echoic memory is about 3 secs. This is much longer than the 0.5 secs that information in memory lasts.

Cowan (1984), says echoic memories last longer because of the important role language.

Darwen et al (1972) conducted a similiar study to Sperling's but using auditory rather than visual stimuli. Ppts were presented with spoken recordings of letter and number lists.

Lists were presented over headphones, one list came from the left headphone, one for the right, and one from behind. They were given a cue to remeber one of the lists.

Length of time from the presentation to the cue varied between 0-4 secs.

Darwin found that as time between presentation and cue increased, the recall performance of ppts decreased.

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Definition of Short-term memory (STM)

A temporary memory store that holds limited amount of information for a short period of time.

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STM

A temporary holding area- it has limited capacity, short duration and acoustic encoding.

You need to repeat and rehearse in the STM until used, otherwise it disappears (short duration)

If the set of numbers you are remebering is too long you remeber the latter ones (limited capacity)

You need to verbalise the whole process, repeating the numbers out loud or in your head (acoustic encoding) 

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STM-Capacity

Jacobs (1887) The digit span technique- presenting ppts with sequence of letters or digits at half-second intervals that can then be recalled in the correct order.

He then started by presenting three-item sequences, increasing by one item until ppts were unable to recall the sequence correctly.- this is their digit span.

Jacob found that ppts recalled on average 5-9 items. Digits are recalled better than letters.

Miller (1956) suggested that while STM is indeed limited to 7+- 2

Capacity is determined by the number of 'chunks' of information rather than the number of individual letters or numbers.

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STM-Duration

Atkinson and Shiffrin saw STM as a temporary store. Anything we need to retain for longer periods of time has to be transferred to long term memory.

Craik and Tulving (1973) said it's not about the amount of rehearsel time but it's STM that determines long-term retention. 

They suggested that there are two types of reharsel:

Maintenance Rehearsal- a person keeps info in STM by continually repeating it. (no transfer to LTM)

Elaborative Rehearsel- It is processed in a way to make it meaningful. E.g. you might remeber a new tlelephone number because of its similarity to a number you already know. 

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STM- Encoding

When information arrives in the sensory register, it is still in its original form. (visual image or as a sound)

Atkinson and Shiffrin saw STM as a single storage space that operated in the auditory (or acoustic) modality.

Definition of Modality- Sensory experience such as vision, sound or touch.

Conrad (1964)- STM: he showed ppts a random sequence of six consonants. projected very rapidly on a screen.  

Some ppts were shown consonants that were acoustically similiar (B,C,D,T)

Others were shown acoustically dissimiliar letters (R,F,J,B) It was all in the 5-9 capacity- should have been simple

Ppts frequently made errors of recall. Ppts found it harder to recall acoustically similiar words than dissimiliar ones.

Supported by Posner and Keele

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Definition of Long-term memory (LTM)

A permanent store where limitless amounts of information can be stored for long periods of time.

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LTM-Capacity

Don't know what the capacity of LTM is. Accepted it has no upper limit. 

Loses things because of decay and interference.

Not because of capacity limitations.

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LTM-Duration

It is hard to measure how long LTM lasts, there are few studies.

Bahrick et  al (1975)- Ppts aged up to 74 years were tested on their memory of their former classmates, demonstarating that memories can be accurate for a very long period of time.

He found that people seem to remember things from the past better if they had a cue (photograph).

Accuracy increased when measured by recognition not recall.

How well LTM is recalled depends on how well the information was learned in the first place. 

Bahrick and Hall (1991) tested long-term memory for algebra and geometry. Ppts who had taken maths courses up to secondary school had a steady deline in recall in comparison to those who had taken higher level courses in maths. 

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LTM-Encoding

Research has consistently demonstrated the semantic encoding, is preffered in LTM.

Baddely (1966)- he found that ppts had difficulty remebering similiar sounding words when tested immediately, but after 20mins had greater difficulty remembering words of the same meaning. 

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Strengths of the Multi-store model

  • It has enabled psychologists to construct models of memory that can be tested and further refined. (The model is influential as it has generated a lot of research into memory)
  • The model is supported by studies of amnesiacs: For example the HM case study. HM is still alive but has marked problems in long-term memory after brain surgery. He has remembered little of personal (death of mother and father) or public events that have occurred over the last 45 years. However his short-term memory remains intact.
  • Many memory studies provide evidence to support the distinction between STM and LTM (in terms of encoding, duration and capacity).  
  • It is supported by the primacy and recency effect (you can remember the start of a piece of info as its in your long term store, you can remember the end as its still in your short term store)
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Weaknesses of the Multi-store memory

  • The model is oversimplified, in particular when it suggests that both short-term and long-term memory each operate in a single, uniform fashion. 
  • It has now become apparent that both short-term and long-term memory are more complicated that previously thought.  For example, the Working Model of Memory proposed by Baddeley and Hitch (1974) showed that short term memory is more than just one simple unitary store and comprises different components (e.g. central executive, visuo-spatial etc.).
  • Different types of LTM exsist: Episodic, Procedural and Semantic.
  • The model suggests rehearsal helps to transfer information into LTM but this is not essential. Why are we able to recall information which we did not rehearse (e.g. swimming) yet unable to recall information which we have rehearsed (e.g. reading your notes while revising). Therefore, the role of rehearsal as a means of transferring from STM to LTM is much less important than Atkinson and Shiffrin (1968) claimed in their model.
  • The multi-store model has been criticized for being passive/ one way/ linear model
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The Working Memory Model

Baddeley and Hitch (1974) reffered to the case of patient KF who only had a digit span of 2 but could transfer new info into LTM.

They concluded that STM must have more than one component and must be invloved in processes other than simple storage.

It's a flexible, complex system.

Episodic buffer was added later

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Definition of the Central executive

The part of the working memory that coordinates other components

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Definition of the Phonological loop

The part of working memory that deals woth auditory information.

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The central executive

It has limited capacity, but can process information from any sensory system.

It is an important control process (attention, monitoring, correcting errors and setting goals)

This core component is supported by slave systems, the phonological loop, the visuo-spatial sketchpad and the episodic buffer. 

They can be used as temporary swtroage ystems freeing up capacity in the central executive to deal with more deanding inofrmation processing tasks.

Hardest to investiagte and has the least research. The research that is there focuses on areas of the central exuctive rather than the whole.

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The phonological loop

Limited capacity, temporary storage sytem for holding vebal information in a speech-based form.

Phonological store (inner ear)- linked to speech perception, holds information in speech-based form (i.e. spoken words) for 1-2 secs

Articulatory control process (inner voice)- linked to speech production. Used to rehearse and store verbal information form the phonological store.

Baddeley et al (1975) gave visual presentations of 5 word lists for very brief exposures and then asked ppts to write them down in the same order. 

In one condition, the lists consisted of single-syllable english words.

In the second condition, the words were polysyllabic (2 or more syllables)

The average correct recall over several trials showed a marked superiority for the short words.

Baddeley called it the 'word length effect'- the time it takes for the word to be said rather than by the number of items. They estimated this time to be 1.5 secs

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Definition of the visuo-spatial sketchpad

The part of working memory that deals with visual information

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Definition of the episodic buffer

A part of working memory which is a temporary store integrating information from the other components.

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The visuo-spatial sketchpad

It is the "inner eye"

It has limited capacity, temporary memory system for holding visual and/or spatial information.

Klauer and Zhao (2004) asked ppts to carry out one of two tasks, either a visual task or a spatial task. At the same time as doing one of these tasks. Either a spatial interference task, or a visual interference task.

They found that a spatial memory task was more strongly disrupted by spatial than by visual interference.

Brain imaging studies have also provided evidene for seperate spatial and visual systems.

Todd and Marois (2004)- More activity in the left half of the brain of people carrying out visual working memory tasks, but more in the right half of the brain during spatial tasks.

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The episodic buffer

To provide a general storage facility

Baddeley (2000) to the working memory model as an explicit component because of research findings that the original model couldn't explain.

Immediate memory for pose is much greater than for unrelated words. (recll of a 100 word paragraph opposed to 100 words in a random order.

Working memory model can't account for this

Remebering prose requires complex information processing 

Baddeley therefore proposed that there must be an additional subsystem

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Strengths of the working memory model

  • Researchers today generally agree that short-term memory is made up of a number of components or subsystems. The working memory model has replaced the idea of a unitary (one part) STM as suggested by the multistore model.
  • The working memory model explains a lot more than the multistore model. It makes sense of a range of tasks - verbal reasoning, comprehension, reading, problem solving and visual and spatial processing. And the model is supported by considerable experimental evidence.
  • The working memory applies to real life tasks, reading (phonological loop), problem solving (central executive) and navigation (visual and spatial processing)

  • The KF Case Study supports the Working Memory Model. KF suffered brain damage from a motorcycle accident that damaged his short-term memory. KF's impairment was mainly for verbal information - his memory for visual information was largely unaffected. This shows that there are separate STM components for visual information (VSS) and verbal information (phonological loop).
  • The working memory model does not over emphasize the importance of rehearsal for STM retention, in contrast to the multi-store model.
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Weaknesses of the Working memory model

  • Lieberman (1980) criticizes the working memory model as the visuo-spatial sketch pad (VSS) implies that all spatial information was first visual (they are linked). However, Lieberman points out that blind people have excellent spatial awareness, although they have never had any visual information. Lieberman argues that the VSS should be separated into two different components: one for visual information and one for spatial. 

  • There is little direct evidence for how the central executive works and what it does. The capacity of the central executive has never been measured.

  • Working memory only involves STM so it is not a comprehensive model of memory (as it does not include SM or LTM).

  • The working memory model does not explain changes in processing ability that occur as the result of practice or time. 

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Types of LTM

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Definition of Declarative memory

Long term memory for "knowing that"

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Definition of Procedural memory

Long-term memory for "knowing how"

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Distinction between Declarative and procedural mem

Milner (1962) discovered that HM was able to learn to trace a shape using its mirror image, and retain this skill over a number of days. HM was able to ise procedural memory to learn this skill, his operation had damaged his ability to use his declarative memory to consciously recollect this experience.

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Defintion of Semantic memory

A type of long-term memory for information about the world that is not linked to particular events or contexts. 

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Defintion of Episodic memory

A type of long-term memory for specific events and experiences in our lives.

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Explanations of forgetting

Info can be lost in a number of ways.

The capacity limits STM, new info in STM can only be accomodated if existing info is displaced.

The limited duration of info in STM means without reharsel info decay quickly

Forgetting from LTM is often explained by interference theory and failure to find (i.e. retrieved) relevant info. 

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Defintion of Interference theory

Memory can be disrupted not only by previous learning but also by what is learned in the future.

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Proactive and retroactive interference

Proactive interference (pro=forward): occurs when you cannot learn a new task because o an old task that had been learnt. When what we already know interferes with what we are currently learning- where old memories disrupt new memories.

Retroactive interfernce (retro=backward): occurs when you forget a previously learnt task due to the learning of a new task. In other words later learning interfers with earlier larning-where new memories disrupts old memories.

Waugh and Norman (1965) provides evidence for retroactive interfernece. They presented ppts with a sequence of 16 digits, after which they were shown one of the digits from the list. Ppts had to say which digit in the sequence appeared just prior to this probe. Researchr found that fewer items there were following the probe in the original sequence, the more likely the ppts were to recall the preceding digit correctly. (retroactive interference)

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Definition of Retrieval failure

Difficulties in recall are due to the absense of the correct retrieval cues.

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Retrieval failure

Tulving and Thompson (1973)- the encoding specificity principle- you are more likely to forge something when the context during encoding is different to that during retrieval.

Marian and Fausey (1986)- they found that memory for a story was better if the language in which it was presented and the language that was used to test memory were the same.

Ppts were residents of Chile, who were fluent in Spanish and English. 

They were required to listen to 4 academic type stories, 2 in Spanish and 2 in English.

Shortly after they were questioned about each story and asked to answer in the same language

Half the stories matched the language and half didn't.

Ppts who heard the story and questions in the same language had greater accuracy of recall.

Shows encoding specificity, as memory is better when there is a match between contects during encoding and retrieval- the language used in the questions provided a retrieval cue for the recall of story details.

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Factors affecting eyewitness testimony

Juries have great reliance on the EWT

Fruzzeti et al (1992) suggested that thousands of people are wrongly convicted every year on the basis of inaccurate EWT.

Wells at al (1998) have reported 40 cases in the US where individuals have been convicted based on EWT, and cleared on DNA.

5 of these were awaiting execution.

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The effects of misleading information on the accur

The memory laid down at the time seem to be quite fragile and subject to distortion by post-event information. Misinformation canintroduce series errors into Eyewitnesses' recall of events.

Loftus (1992) called this 'misinformation acceptane' - people accept misleading info after an event and absorb it into their memory for the actual

Time since the event ocured increases = tendency to accept misleading post-event information is greater.

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Leading questions and post-event discussion

Loftus and Zanni (1975) showed ppts brief clips of a car accident and then asked a series of questions. 

1/2 the ppts were asked whether they had seen 'a broken headlight'

1/2 were asked if they had seen 'the broken headlight'

There was no broken headlight in the flim.

7% said they'd seen it for "a"

17% said they'd seen it for "the"

Ppts in "the" also gave fewer 'I don't know'.

'the' leads people to belive there was a broken headlight.

The misinformation effect through the use of leading questions has been replicated in many studies.

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Defintion of a leading question

A quesion phrased in a sucha way that it prompts a particular kind of answer.

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Loftus and Palmer (1974)

Showed 45 ppts a film of a car accident.

They were then asked to describe events as though they were eyewitnesses' 

They were asked a series of specific questions about events leading up to the accident.  

One critical question concerned the speed of the car on impact .

One group was asked how fast the cars were going when they Hit each others

Other groups also asked when: Smashed, Bumped, Collided or Contacted.

Contacted- 31.8mph

Smashed- 40.8mph

Week later ppts asked Did you see any broken glass? Smashed condition were more likely to say yes, even though there was none.

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Reasons why memories are affected by misleading in

Due to the constructive nature of long-term memory, leading quesions actually cahnge a witness's perception of the event, resulting in false memory. Recall reflects the actual memory of the event, though the memory is flawed.

Loftus and Palmer (1974) suggste that some people do not have a fasle memory of an event as such, but the retrieval of informationn fom their long-term memory is being influenced by the misleading information.

Loftus (1980) offered a reward if ppts if they could recall details from a film of an accident.

One group saw a pedstrian being knocked over after a car had stopped at a stop sign.

The other group saw the same incident but the car had stopped at a give way sign.

2 days later they were gien a questionnaire. Criticl questions asked stopsign ppts about the give way sign and visa versa. Loftus then asked all the ppts to look at pairs of slides and point out, whichone had been part of the original film.

Ppts split into four groups with varying rewards. Despite the fiancial incentive, 70% of the ppts made an error on the crucial question.

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The effects of anxiety on EWT

Loftus and Burns (1982) showed soe ppts a very voilent version of a crime in which a boy was shot in the face. These ppts had significantly impaired recall of the events running up to the shooting.

Supported by Deffenbacher et al. (2004)- They did a meta-analysis of experimental studies into the effects of anxiety on eyewitness memory and found, high levels of anxiety had a negative impact, not only on accuacy of crime-related details, but also on identity of the perpetrator.

Loftus (1979) reported the "weapon effet", eyewitnesses pay particular attention to the weapon used in the rime, meaning other aspects of the scene goes unobserved.

Loftus (1979) ppts sat outside a lab, thinking they were hearing genuine people inside. One condition say heard there was equipment failure. Man with greasy hands came out of lab with a a pen. econd condition theyheard hostile discussion, sound of breaking glass and overturned furniture, man emerge with bloddy knife.

Ppts given 50 photos and asked to identify the man. Peacful scene had higher accuracy. (49%) vs 33% violent scene. (bloddy knife took attnetion away from mans face.

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Improving the accuracy of EWT

Geiselman et al. (1985) developed a technique for improving the accuracy of eyewitness recall during police investigation.

  • Context Reinstatement (CR) - Menatally reinstate the conext of the event. Recall the scene, the weather, thoughts and feelings at the time.
  • Report everything (RE) -Report every possible detail even if it seems trivial or irrelevant.
  • Recall from a changed perspective (CP) - Try to describe the episode as though it would have been from a different perspective.
  • Recall in reverse order (RO) - Change the order of recall so that the event is reported in different orders,moving backwards and forwards in time.
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Defintion of The cognitive interview

An interview technique devised to improve the accuracy of witness recall.

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The Cognitive Interview

Investigated the effectiveness of the cognitive interview by comparing it to other means used to aquire eyewitness testimony.

89 ppts were shown police training films of simulated violent crimes. 48 hours later they were interviewed about the films by an experienced LA police officer, using either a cognitive interview, a standard polie interview, or an inerview using hypothesis. The interviews were recorded and eyewitness reports assessed for correct and incorect responses.

He found that the cognitive intrview elicited the most accuate recall, followed by hypnosis and then started the interview.

The similarity of results for the cognitive interview and hypnosis was thought to be due to two techniques, RE and CP.

The standard interview did the worse beacuse of repeated focus on encouraging recall f key information without aids to memory retrieval.

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