Memory Studies

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Capacity in STM - Jacobs

Aim: To investigate how much info can be held in STM

Procedure: -Lab experiment, Using the digit span technique 

                 -P's verbally presented with a sequence of digits, increasing in length on each trial.

                 -The presentation time between each digit was half a second.  The trial ended when                   the p failed to recall digits correctly

Findings: The average recall was between 5 and 9 digits.

Conclusion: STM has limited capacity between 5 and 9 items.  This is not determined by the                        nature of the info, but the size of the STM.


  • The study has led to further research - e.g. Miller described the capacity of STM as 'the magical number  7+/-2'.  Also showed Chunking could improve the amount that could be held in STM
  • Findings have been usefully applied to aid memory.  e.g. tellephone numbers, postcodes etc. are based on digit span and chunking 
  • Lab exp and an unmeaningful task - lack mundane realism.  Its possible that STM capacity is greater for everyday memory.
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Duration in STM - Perterson and Peterson

Aim: To test that info in STM has a duration of about 20 secs without rehersal.

Procedure: -Lab exp.

                -P's presented with a trigram of 3 constanants. 

                -They had to recall after a delay of 3,6,9 secs etc up to the time they couldnt recall                          correctly

                -To prevent rehersal, p's had to count back from 300 in threes out loud.

Findings: Recall decreased steadily between 3 and 18 secs

Conclusion: the memory trace just about disappeared after 18 secs elapsed


  • Lab exp - highly controlled; the IV is under the manipulation of the experimenter, and cause and effect can be inferred.
  • Lacks mundane realism - does not reflect how we remember in everyday life.
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Duration in LTM - Bahrick et al

Aim: To investigate the duration of LTM in a real life setting.

Procedure: -Oportunity sample of 392 ex-high school students from 17-74 years taken.

                 -Asked to undertake 2 tasks: (1) free recall of former students in their class; and (2)                         recall names from a photograph. 

                 -Some of the photos werent from the school.

Findings: A 90% accuracy of photo recall was found and free recall declined with age.

Conclusion: Face and face recognition are rarely forgotten when recognition cues are given,                              supporting the contention that recognition is better than recall.


  • Does not take place in lab, therfore high mundane realism 
  • It was representitive of a more natural activity that people might do, has high ecological validity and thus findings can be generalised to other settings.
  • There may have been opportunities to revist the photos over a persons life, which is akin to rehersal, and there may have been contact with people.
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Encoding in STM and LTM - Baddeley

Aim: To show that encoding is mainly acoustic cod in STM and semantic in LTM

Procedure: -Independant measures design

                 -One group asked to recall words immediately (STM) and another asked to recall                         after a delay of 20 mins (LTM)

                 -4 lists were presented: the first pair had one list of words with similar sounds and a                         control of words with non similar sounds

                 -The second pair had one list of words with similar meaning and a control of words                     with dissimilar meaning.

Findings: In the STM the words that sounded similar were least well remembered and in LTM                   the words with similar meaning were least well remembered.

Conclusion: The importance of sound was shown in ST and the importance of meaning in                             LTM.  This has implication for improving memory.


  • Lacks mundane realism - the recall task is not representative of what we do in everyday life.
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Encoding in STM - Conrad

Aim: To investigate whether people use acoustic coding when ifo is presented visually.

Procedure: - P's shown a sequence of 6 consonants, either similar in sound or dissimilar, in rapid                       succession.

Findings: Most errors came when the sounds were similar. e.g. B and V

Conclusion: Even when ifo is presented visually, p's encode acoustically in STM.


  • Although acoustic encoding may be preferable, there are other ways in which humans encode info in STM.  
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The Serial Position Effect - Glanzer and Cunitz

Aim: To show that when presented with a list of words, the first few and the last few are                         remembered, but those in the middle are forgotten.

Procedure: -A list of words was presented to the p's, who were asked to recall the list in order.

Findings: p's could rememeber the first and last few, but not those in the middle.

Conclusion: First few remembered because they had already been transferred to LTM and last few                    rememebered because they were still in the STM.  This supports the idea that STM                        and LTM are 2 different stores.


  • supported by a no. of other studies that show that STM and LTM are qualitatvely different types of stores.
  • a lab study where people are recalling word lists is not a normal practise and therefore lacks mundane realism and ecological validity.
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How Eyewitness testimony is affected bu misleading


Aim: To investigate the effect of a leading question on eyewitness accounts

Procedure: -Lab exp.

                 -shown video clip of car accident

                 -P's divided into groups

                 -Each p only did 1/5 groups, making it an independant groups design.

                 -Each group given a questionaire that included a critical leading Q, wich was slightly                         different for each group.

                 -The Q for one group was: 'How fast were the cars going when they smashed into                       each other?'.  For the others the word smashed was changed to 'bumped', 'hit',                           'contacted' and 'collided'.

Findings: Those p's that heard the emotive word 'smashed' estimated the highest speed.


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How Eyewitness testimony is affected by misleading


Aim: To investigate the effect of leading Q's on later recall of memory

Procedure: -p's (3 groups) watched a video of a car accident.

                -Then filled in a questionare with the same critical leading Q as the one above asked.

                - G1 given word 'hit', G2 'smashed' and G£ not asked the leading Q (control group)

                -1 week later the groups returned and asked 'Did you see any broken glass?' (there                       was non in the video)

Findings: More p's in 'smashed' group reported seeing broken glass that the other 2 groups.

Conclusion: The 'memory' or some p's influenced by word 'smashed', which led them to assume a                     higher speed.  This is turn meant that they were more litkely to report seeing broken                       glass, suggesting that leading Q;s do have an effect on EWT.

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How Eyewitness testimony is affected by misleading


  • Experiment was very well controlled and p's well matched.  Info was exactly the smae for all p's.
  • Research has canged the way Q's are asked by the police and in the law courts 
  • watching a video isnt the same as seeing things in real life.  Lacking ecological validity.
  • Students were used and their memory might be very good.  validity may be questoned, as the smaple wasnt represtative of the general population.
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How Eyewitness Testimony of a crime is affected by

Aim: To investigate eyewitness accounts of a real event.

Procedure: -Police interviewed 21 witnesses of a real life shooting in the street.

                -Few months later, 13 agreed to be re-interviewed.

                -Natural Study, though not an everyday occurance

                -One misleading Q during the interview was added which was about a 'busted' headlight                  on a car.

                -P's also asked about a slightly different coloured panel on the car.

                -The deets of the event were reconstructed from photos, the police and other                                  professionals.

Findings: Much more info was obtained from the research interview than from the police interview,                 and the misleading Q had no effect.

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How Eyewitness Testimony of a crime is affected by

Conclusion: Contrary to some research, the violence of this event didnt detract from the accurate                       reporting by witnesses.  Other research (usually lab exp.) has suggested that violent                       situations tend to elicit responses that are less accurate.


  • High ecological value - real life situation 
  • A police interview situation may not be the best place to recall an event like this, whereas the researchers may have provided a more ambient setting, making it easier for recall.  the study might therefore have lacked reliability.
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Effect of Anxiety on EWT

1) Peters 

  • When recieving injections, p's didnt recognise a picture of the face of the nurse a week later

2) Loftus

  • Weapon Focus effect
  • P's tend to focus their gaze on the gun rather than on the criminal

3) Loftus and Burns

  • There is better recall of the deets of less violent crimes than violent crimes.
  • Violence causes anxiety, which influences recall
  • Contridicted by Yuille and Cutshall, who found that high anxiety in real-llife gun crime produces higher correct recall.
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Effect of Age on EWT - studies on Children

1) Ceci 

  • 3-4 year olds are most susceptible to reconstructing an event when given a leading Q.

2) Goodman and Schaff 

  • Language ability - understanding of the question affects recall.

3) Saywitz

  • Young children recall less complex memories than older children.  Their memories appear incomplete and 'made-up' - a child can 'invent' extra recall.
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Effect of Age on EWT - studies on the elderly

1) Cohen and faulkner

  • The lederly and young are more prone to the effects of leadingQ's than young adults.

2) Inaccuracy of performance in picking out a person on an identity parade may be very different with young children and the elderly from a young adult.

3) Anastasi and Rhodes 

  • Young and middle aged people are better than the lederly at recognising photos.
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A study of the Cognitive Interview (CI) - Fisher e

Aim: To test the effectiveness of the CI technique.

Procedure: -Interviews conducted by 16 experienced police officers from Florida, 7 of whom where                     trained to use the CI technique.

                -The witnesses/victims  were interviewed twice.

                -The experimental group conducted 2 standard interviews

                -The IV was identifed as the type of interview and the DV was the no. of accurately                        recorded facts.

Findings: The CI obtained 47% more facts than the standard procedure.  The control group on the                 second standard interview didnt improve its scores.

Conclusion: The CI is a useful technique to improve EWT

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A study of the Cognitive Interview (CI) - Fisher e


  • Interviwers real police men, witnesses were real in recalling event that happened, so high ecternal validity.
  • Officers trained in CI may have been better interviewers.  The non-trained officers might not have felt so competent.  There may also have been a difference in how interviewers appeared to the witnesses, which could have affected performance.
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