STM and LTM - Duration

AO1 for STM

Peterson and Peterson:

  • 24 university students as participants
  • Gave them a consonant syllable followed by a 3 digit number.
  • Told to count back in 3's or 4's to prevent rehearsal.
  • 2 practice trials, 8 real trials - 3,6,9,12,15,18 retention intervals
  • 90% for 3 seconds - 2% for 18 seconds
  • STM Duration = 20 seconds max

AO1 for LTM

Bahrick et al:

  • Asked participants to match names to faces from a high school year book 48 years later
  • Accuracy was 70%


  • Gave participants 612 memorable pictures one by one. 
  • 1 hour later when these pictures were mixed with other pictures, people could still recognise the orginal pictures correctly
  • Even after 4 months, recognition rate was 50%.
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STM and LTM - Duration Evaluation

AO2 for STM

Nairne et al

  • Found that STM could last up to 96 seconds.
  • In his study, he made participants recall the same items across trials. Rather than different items each time.
  • Suggests that STM can last a while aslong as it isn't overwritten.

Marsh et al

  • Participants in the Peterson study knew that they were going to asked the 3 letters given to them originally.
  • Marsh suggests that forgetting can occur after 2 seconds if we didn't know we were being tested.
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STM and LTM - Capacity

AO1 for STM

Joseph Jacobs 'Digit Span Technique'

  • Used the digit span technique to find out the capacity of STM.
  • Average span for digits 9.3 and for letters 7.3
  • More for digits because there are less of them.

George Miller

  • Reviewed psychological research and wrote the article 'the magic number seven plus or minus two'
  • Concluded that the span of immediate memory is 7.
  • Also found that people can recall 5 words as well as 5 letters because of chunking.
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STM and LTM - Capacity Evaluation

AO2 for STM

Joseph Jacobs

  • Found that capacity increases with age.
  • 8 year olds 6.6 digits whereas 19 year old 8.6 digits
  • He says this is because of increase in brain capacity and as you get older you develop more strategies to improve capacity.
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STM and LTM - Encoding

AO1 for STM & LTM


  • Tested the effects of acoustic and semantic similarity on short and long term recall.
  • Gave participants lists of words that were semantically similar/ disimilar and acoustically similar/disimilar
  • Found that participants found is hard to remember acoustically similar words in STM.
  • Also found that participants found it hard to remember semantically similar words in LTM as it led to muddled memories.

AO2 for STM & LTM - they do use other types of processing

Brandimote et al

  • Found that STM uses visual encoding when participants are given a visual task and are prevented from doing any verbal rehearsal.
  • NOT BRANDIMOTE - LTM may use others such as visual encoding and there is even evidence for acoustic encoding.
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The Multi-Store Model

Atkinson and Shriffin

  • Made up of 3 stores: Sensory Memory Store, STM store and LTM store

Their original explanation:

1. Environmental stimuli (what we we hear and see) goes into the sensory memory store.

2. However, in order for it to go further attention must be paid to the info in the sensory memory store from the environmental stimuli.

3. If attention is paid, it goes into the STM store. Maintenance rehearsal is then needed to keep it in.

4. In order to move it to LTM, maintenance rehearsal has to keep happening and the more we rehearse something the more likely it is to move into our LTM.

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The Multi-Store Model Evaluation

AO2 Support

Glanzer and Cunitz

  • Gave participants 20 words one by one and asked them to recall them in any order.
  • They tended to remember the first and last words of the 20.
  • First - because it has been rehearsed and moved into the LTM
  • Last - still fresh in the STM
  • Middle - these words have been overwritten in the STM

PET scans and fMRI

  • Modern day brain scanning technology can show us what parts of the brain are active when someone is doing a certain activity.
  • It has been found that when the STM is at work the prefrontal cortex is active and when the LTM is at work the hippocampus is active.
  • This shows a clear distinction between the two memory stores.

Criticism - KF Case Study suffered brain damage, difficulty in dealing with verbal info but not visual. Shows STM is not a single store

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Working Memory Model

Baddeley and Hitch

Central Executive: Key component of the WMM. It allocates information to the slave systems. Limited capacity and duration. 

Phonological Loop: deals with auditory information. This can be split into two parts: Phonological store (keeps hold of info) and the articulatory process(allows maintenance rehearsal). Limited capacity and duration

Visuo-spatial sketchpad: deals with visual and spatial information. Limited capacity and duration.

Introduced in 2000 - Episodic Buffer

  • Limited capacity
  • Integrates all info from the slave systems and LTM.
  • Used for tasks involving visual encoding and acoustic encoding at once.
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Working Memory Model - Evaulation

AO2 Support

1. Baddeley and Hitch

  • Gave participants two tasks to do at the same time
  • Task 1 - occupied the central executive and was slower when task 2 involved the CE and the PS
  • Task 2 - either involved the phonological store, phonological store and central executive or no extra task at all and the pace of task 1 was the same whether using phonological store or no extra task.

Task 1 was slower when task 2 had the CE and PS involved because the CE has limited capacity and they had to deal with that.

Task 2 was the same pace because different components were used.

2. Shallice and Warrington

  • KF case study
  • LTM = Good ; STM = Impaired
  • His short term forgetting was mainly for auditory information, but nowhere near as much for visual info.
  • Therefore, there are seperate stores in STM.
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Working Memory Model - Evaulation

Criticism AO2

1. Central Executive Mare

  • Some psychologists are puzzled on the role of the central executive. It is essentially the same as 'attention' in the multi-store model. They feel the description of the CE is too vague.
  • Critics also argue that the idea of there being 1 central executive is wrong.
  • Eslinger and Damasio
    Case study of - EVR who had cerebal tumour removed
    - He perfomed well on reasoning skills tests which suggested that his CE was intact.
    - But his decision-making was poor (spend hours thinking of a place to eat) which suggests that his CE wasn't fully intanct.
    - This could suggest there is more than one central executive.

2. Evidence for the WMM

  • Evidence to support the WMM come from case studies with brain damaged patients.
  • We cannot make 'before and after' comparisons, so we dont know if changes are actually caused by the damage.
  • Brain injury is traumatic, and hard to understand. We never know what really happens and many cases are completely different.
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Accuracy of EWT

AO1 Key Study Loftus and Palmer

Experiment 1: 

  • 45 students were shown films of different traffic accidents
  • After each film participants were given a questionnaire about the incident with 1 critical question
  • 'About how fast was the car going when they (hit) other?'
  • Different groups were given different verbs (smashed, collided, bumped, hit and contacted)
  • The mean speed was estimate for each group:
    - Smashed (1st) 40.8 mph
    - Contacted (5th) 31.8 mph
  • This shows how inaccurate EWT can be depening on how the question is asked.

Experiment 2:

  • New set of participants divided into 3 groups. Shown a film of a car accident lasting one minute.
  • One group was given the word smashed, the other hit and there was a control group.
  • Participants asked to return a week later and were asked a series of 10 questions with one critical question. 'Did you see any broken glass?' (There was no glass in the film)
  • Participants who had the verb 'smashed' were more likely to think there was glass, even a small amount of participants in the control and and 'hit' group thought there was glass.
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Accuracy of EWT - Evaluation


Yuille and Cutshall - Opposes

  • Interviewed 13 people who had experienced an armed robbery in Canada.
  • These interviews took place 4 months after the crime and included 2 misleading questions.
  • Despite this, the accuracy of recall was quite good.
  • This suggests that accuracy of EWT may not be affected by post-event info.

Real World Applications - Supports

  • Criminal justice systems from many places around the world rely on EWT.
  • Since the introduction of DNA identification, people have been proved to be innocent despite being convicted.
  • This suggests that EWT can be unreliable, like the ones shown in Loftus and Palmers study.

Individual Differences

  • Wells and Olsen - concluded that there is no difference between men and women despite maybe taking more interest in different aspects of the scene
  • Older people are more prone to the effect of misleading info on EWT as they have difficulty remembering the source of their information.
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Factors that influence the accuracy of EWT

Anxiety (and weapon-focus effect)

1. Deffenbacher et al - Negative

  • Meta-analysis of 18 studies (70s-90s) looking at the effects of anxiety on EWT.
  • He found that there was considerable support for the idea that high levels of anxiety negatively impacts the accuracy of EWT.

2. Christianson and Hubbinette - Positive

  • Questioned 58 witnesses to a real bank robbery.
  • The witnesses who had been threatened in some way, were more accurate in recall and remembered more details than those who did not.
  • This continued to be true even 15 months later.

Weapon-focus effect - Loftus et al

  • Condition 1 - participants heard a discussion in an adjorning room, a man emerged with a pen in his hand and his hand was greasy
  • Condition 2 - participants heard a more heated discussion and a man emerged with bloody hands and a paperknife
  • When asked to identify the man from 50 photos, pps in condition one were 49% accurate compared to 33% in condition two
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Anxiety (and weapon-focus effect) - Evaluation

AO2 for Anxiety:

  • Deffenbacher suggests that this apparent contradicition between the two researches  is best explained using the Yerkes-Dodson law.
  • This means that performance increases up to a certain point, and then it begins dropping.
  • Many researchers believe the affects of anxiety on EWT are curvilinear.

Riniolo et al

  • Examined the accuracy of EWT from survivors of the sinking titatinc in 1912.
  • Until the wreck was discovered in 1985, it was widely accepted that the titanic sunk all at once despite contrary evidence from eyewitnesses in which 75% of them said the titanic was breaking apart as it sank.
  • In 1985, eyewitnesses were proved right when it was found that different parts of the boat were 2,000 feet away.
  • This shows that details of an event can be recorded accurately under intense stress and anxiety.

Evaluation for weapon-focus effect:

  • Steblay -done a meta-analysis and found that the prescene of a weapon does reduce EWT.
  • Loftus et al - monitored eyewitnesses eye movements and found that presence of a weapon, causes attention to be more drawn towards the gun/weapon and away from other things such as the person's face
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Factors influence EWT - Age


1. Parker and Caranza

  • Compared primary school children to college students in their ability to identify an individual after a mock crime slide sequence
  • In a photo identification task, primary school children were more likely to choose someone, but were more likely to make errors of judgement.

2. Yarmey

  • Stopped 651 adults in the street and asked for the physical characteristics of one women, in whom they had spoken to for 15 seconds, 2 minutes ago.
  • Young (18-29) and middle aged (30-44) participants were more confident in recall than older (45-60)
  • Found no real difference in recall between ages.

3. Menon et al

  • Studied the accuracy of EWT when the time between incident and recall is increased.
  • When they delay was 35 mins = no difference between young (16-33) and older witnesses(60-82)
  • When the delay was a week = older witnesses were less accurate
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Age - Evaluation

AO2: Anastasi and Rhodes

  • Used 3 groups young (18-25) , middle aged (35-45) and older (55-78)
  • Were shown 24 photos and asked to rate them for attractiveness.
  • After a short 'filler' activity, they were shown 48 photographs (24 new and 24 old)
  • When it came to recognising the original 24 photos, young and middle aged participants were better than older partiticpants
  • However, interestingly for each of the 3 groups, they had better recognition rates for their own age group. This is known as own-age bias.


  • We have more contact and interaction with people for our own age group.
  • Therefore, we can process faces of people our own age group better.
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Cognitive Interview

  • Made by Fisher and Geiselman
  • They reviewed psycholigcal literature and related this to the way police carry out their 'standard' interviews to make the Cognitive Interview.

1. Report Everything - the interviewer asks the witness to recall every single detail, even if it seems irrelevant.

2. Context reinstatement - interviewer encourages the witness to mentally recreate the situation and the environment of the incident

3. Changing the order - the interviewer encourages the witness to change the order of events. E.G/ Start at the end and finish at the start

4. Changing the perspective - the interviewer asks for the witness to change their perspective by maybe putting themselves in somebody else's shoes.

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Cognitive Interview - Evaluation


1. A meta-analysis of 53 studies found that on average the CI can increase accuracy by up to 34% in the amount of correct information generated. However, some of these studies were lab experiments with volunteers.

2. Brazil Study

3. Time-consuming

4. Not all police forces use it, have to be trained

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Strategies for memory improvement


Verbal mnemonics

  • Gruneberg - surveyed psychology students revising for exams. Found that 30% used mnemonics in their revision - with acronyms and acrostics the most popular.
  • Gidden et al - found that verbal mnemonics were helpful for children with disabilities, although this wasn't evident 12 months later when compared to a control group

Visual imagery mnemonics

  • O'Hara et al - training in visual imagery mnemonics such as the method of loci creates long term benefits especially for older people
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