- Memory- mental process to encode, store and retrieve information.
- Encoding- change information to a different form, STM encode rehersal terms sound, LTM encode terms meaning.
- Capacity- STM limited capacity, 7 items, LTM unlimited capacity, potentially last forever.
- Duration- info last longer in LTM than STM, if not rehearsed, loose from STM in 18-20seconds. elderly recognise names fellow students 48years ago.
- Storage- result encoding, info stored memory system, remain for long time, entire life.
- Retrieval- recover info from memory system, recall on remembering.
Peterson and Peterson
- AIM- study duration STM, info not rehearsed, lost rapidly.
- PROCEDURE- used brown-peterson technique, trigram of 3 consonants e.g. BVM, CTG given to participant, knew had to read correct order.
- Recall delay 3,6,9,12,15 seconds, between time asked count back random 3 digit number.
- Assesed by number of trigrams correct.
- FINDINGS- after 3 seconds, 80% correct, 6 seconds 50% correct, 18+ seconds, fewer than 10% remembered.
- CONCLUSIONS- Little information remain in STM after 18 seconds if rehersal prevented by another task.
- Lab experiment, repeated measures design
- Lack mundane realism, repeated trials may have confused participants, only 1 stimulus measured, not pictures/smells/melodies etc.
- AIM- investigate nature coding in STM
- PROCEDURE- present participants series 6 letters, have 0.75 seconds per letter selected from B C F M N P S T V X
- Write down order immediately after and analyse errors.
- FINDINGS- many made errors substitiute letters that sound the same not look the same, acoustic confusions e.g. write B for V or F for S etc.
- CONCLUSIONS- STM is encoded semantically (by sound) rather than meaning.
- lab experiment, high control, lack of extraneous variables
- not rule out other methods of coding, assume semantic but other studies do rule out other methods of coding possible e.g. Baddeley proved mainly semantic coding used.
Bahrick et al
- AIM- investigate duration of VLTM (very long term memory), to see if it lasts for decades, and support assumption duration of LTM is a lifetime. Also aimed for external validity by testing on real life information.
- PROCEDURE- 329 American ex-high school students aged 17-74, opportunity sample.
- Given free recall of school, photo recognision test of 50 photos, some were/weren't classmates, name recognision test, name/photo match test. Accuracy against yearbook.
- FINDINGS- 90% accuracy on face and name recognision, after 48yrs drop to 80%, face regonition 40%, on free recall 60% accurate, after 15yrs, after 48yrs drop to 30%
- Classmates rarely forgotten, after given clues.
- CONCLUSIONS- Memory can last a lifetime, although accuracy and details may be lost.
- evidence assumptions of LTM duration, high mundane realism.
- Very particular type of information to recall.
- AIM- Investigate how the LTM and STM are encoded.
- PROCEDURE- participants gien 4 sets words to recall in order, STM recall immediately, LTM longer time given
- 1- words sound similar, e.g. cat, map, lap, man.
- 2- words sound different e.g. dog, bin, cup, pen.
- 3- words similar meaning e.g. big, large, huge, vast.
- 4- words different meaning e.g. huge, good, light, blue.
- FINDINGS- STM made more mistakes on words that sound alike.
- LTM made more mistakes on words with similar meaning.
- CONCLUSIONS- STM is encoded acoustically, whereas LTM is encoded semantically.
- controlled environment, lack of extraneous variables as lab experiment.
- lack ecological validity, demand characteristics
- Developed by Atkinson and Shiffrin, describes memory flowing through a system, passing each stage in a fixed sequence, transfer requrires re-coding.
- External stimuli put in sensory memory, as uncoded input. Some information is lost via decay, but some is re-coded to the STM.
- the STM can store information for several seconds, it encodes acoustically. Some information is lost via decay/displacement but if rehearsed, it is transferred to the LTM.
- the LTM is semanticallly encoded and has unlimited capacity, information can still be lost via decay, or retrieval failure.
- distinguish STM, LTM, sensory memory in terms of capacity, duration, encoding.
- evidence for separate stores in primary and recency effects (remember first/last info better).
- too simplistic/inflexible, strategies for memory improvement, focus structure not explanation.
- Rehersal only means of transfer between STM and LTM
- Supporting evidence for Multi-store model.
- H.M. left secure memory impairment after brain surgery.
- Could talk and recall what happened before surgery, but could not recall new information.
- Told uncle died and was in considerable distress, but later asked about him.
- Support model as show clear distinction between LTM and STM as H.M. was able to recall from the LTM but not able to recall new information that was lost in the STM.
Glanzer and Cunitz
- AIM- Give evidence of separate STM and LTM stores (evidence for multi-store model)
- PROCEDURE- participants presented with list of words, asked to recall immediately, then after an interval, count back 30 seconds before recall.
- FINDINGS- after immediate recall, remembered 1st and last words best.
- after delayed recall, remembered 1st best, both had difficulty remembering middle.
- The first words were already in LTM, the end still in STM so could not recall, delay a disruption, unable to rehearse STM, not maintain information givne.
- CONCLUSIONS- There are separate STM and LTM stores due to primary and recency effects.
- lab experiment, high contorl, lack of extraneous variables.
- other researchers interpret differently, recency effect occur as most recent words most distinctive, not held in separate STM store.
- AIM- evidence for existance of sensory memory.
- PROCEDURE- participants look at a chart for 50 miliseconds, asked to recall letters.
- Also asked to recall rows when certain tone played, e.g. high tone is top row, low tone is bottom row etc.
- FINDINGS- Participants could remember 4-5 letters and aware of others.
- In second instance, could remember 3 items from the row.
- CONCLUSIONS- Can remember on average 4 items as each item fades during time of task.
- Sensory memory exists.
- lab experiment, high control of variables, easily replicated.
- lack of ecological validity.
Working Memory Model
- STM a flexible multi-component system, explain why able to to two tasks separately as use different storages in the STM.
- Evidence supporting that each system exists, explain ability to do mental maths, store numbers and process at the same time.
- Central executive, main component most ambiguous, not much mentioned of LTM.
Robbins et al
- AIM- study the role of central executive in remembering chess positions.
- PROCEDURE- 20 chess players had 10 seconds memorise 16 chess pieces from a real game, repeated 20 times with different games.
- While memorising, either had to generate random letter strings or do an articulatory suppresison task (e.g. say "the" continuously)
- After they were given 10 seconds to place pieces on board in same way.
- FINDINGS- with articulate task, participants performed well, but with letter strings, performed weakly as central executive was engaged.
- CONCLUSIONS- Central executive plays a role in remembering chess positions as when suppressed, the positions cannot be recalled correctly.
- repeated with different games so pieces in different places, meaningless letter generation is a valid way of engaging the central executive.
- population bias, very specified task.
Baddeley, Thomson and Buchanan
- AIM- provide evidence for the phonological loop.
- PROCEDURE- participants given brief exposures to lists of words, and asked to write down in serial order. There were two groups:
- 1- Given list 5 familiar, one-syllable words in English e.g. harm, wit, twice.
- 2- Given list 5 polysyllablic words e.g. university, association
- Average recall over several trials recorded.
- FINDINGS- It was easier to remember shorter words over the longer ones.
- CONCLUSIONS- "word length effect", capacity of the loop defined by length of time to say the word rather than amount of items, decay rate is about 1.5 seconds.
- lab experiment, repeated measures design.
- Longer words could just be less familiar not than the shorter ones.
Baddeley, Grant, Wight and Thomson
- AIM- Provide evidence for visuo-spatial sketchpad.
- PROCEDURE- Participants given a simple tracking task, e.g. follow point of light in circular path, and visual imaging task, imagine block capital, start bottom left corner, say yes if the corner touches the top/bottom line and no if doesn't.
- FINDINGS- participants had enormous difficulty doing both at once, as both tasks competing for resources of visuo spatial sketchpad, but could do task with a verbal task.
- CONCLUSIONS- visuo-spatial skethpad exists as people cannot complete two tasks at once that require the limited resources of it.
- high control lab experiment, repeated measures design.
- Lack mundane realism.
- AIM- provide evidence for the central executive.
- PROCEDURE- participants asked to generate random string digits by pressing numbers on a keyboard. Also had to do one of the following tasks.
- 1- recite alphabet
- 2- count from 1 upwards
- 3- alternate between alphabet and numbers, e.g. A1, B2, C3, D4, E5 etc..
- FINDINGS- numbers were generated less randomly in the 3rd condition as participants fell into patterns, as the tasks compete for the same central executive resources.
- CONCLUSIONS- the central executive exists and has limited resources as if two tasks cannot be completed at once.
- lab experiment, high control of extraneous variables.
- lack mundane realism.
Memory Improvement Strategies
- Bower et al- remember more words when organised to categories rather than random.
- Mnemonics- meaningless naterial made meaninfgul, more memorable, e.g. colours of rainbow remember as Richard Of York Gave Battle In Vain.
- Chunking- reduce what remember into meaningful units e.g. chunks of phone number.
- Method of loci- place items in positions on a familiar route e.g. walk to school then walk route in mind and at each place, will remember the items there.
- Mind maps- organise information with links to eachother, memory essentially involve making associations in brain.
Why do we study Eye Witness Testimony?
- Fruzetti et al- thousands of people wrongly convicted every year on the basis of an inaccurate eye witness testimony.
- EWT can be affected by:
- consequences of testimony
- cognitive interview
- leading questions
- misleading information
Factors affecting EWT
STAGE 1 STAGE 2 STAGE 3
Actual events: aquisition of info storage of info. retrieval later of info.
STAGE 1- can be affected by poor sight, weapon focus and expecations of events.
STAGE 2- can be affected by misleading info and source misattribution errors.
STAGE 3- can be affected by best guessing and leading questions
To be accurate all 3 stages of memory processing must be completed without error.
- Categorise things to make sense of the world.
- Simplified generalised representations based on experience.
- Mental representation to categorise objects.
- Help make sense of familiar situations and interpretations of new information.
Brewer and Treyens
- AIM- see the effects of schemas on visual memory.
- PROCEDURE- 30 participants put in an office for 35 seconds that had 61 objects in it.
- Some of the objects were compatable with the schemas, but some weren't.
- FINDINGS- people were less likely to recall items that didn't fit their schema.
- They were most likely to remember items that did fit with the schema.
- 8 recalled the very bizarre items e.g. a skull
- Most of the errors made were substitutions or placement e.g. pad on desk, really on chair.
- CONCLUSIONS- schemas are used for rapid encoding of visual information
- At the retrieval stage, schemas influence recall, typical items recalled even if not present.
- People remember what is consistent with schema, and filter out the inconsistent.
- high control lab experiment, setting same for each participant.
- demand characteristics
- AIM- investigate effects of schemas on EWT
- PROCEDURE- Participants given list of things may occur in shoplifting incident, then rate which were the most likely to occur.
- 8 videos of shoplifting were complied, that included high and low probability elements from lists.
- They were shown to new participants and they were asked to recall the events a week later.
- FINDINGS- Participants were more likely to remember high probability than low probability events, and some reported seeing high probability events in the videos that did not occur.
- CONCLUSIONS- Participants lost some of the information from the videos due to the delays, so they used their own knowledge to fill in the gaps.
- high control lab experiment, can be related to real life scenarios.
- demand characteristics
Tuckey and Brewer
- AIM- investigate reconstructive memories and schemas
- PROCEDURE- found that most people think of robbers e.g. dark clothes, disguise, male etc. (their schema) then showed participants a video of a bank robbery.
- FINDINGS- Participants had better recall of parts of the film that conformed to schema rather than the elements that didn't.
- CONCLUSIONS- schemas affect the recall of events as the idea is already stored in memory.
- no real ethical issues with experiment.
- some people may have different schemas to others which would affect what they recall
- Misleading information can change the memory of an eyewitness as the information given is incoporated into the memory that wasn't previously there.
- AIM- investigate the effects of misleading information on EWT
- PROCEDURE- participants were shown a set of photo slides leading to a car accident.
- Group 1- a red car stopped at a juntion with a yield sign then answer 20 questions.
- Group 2- a red car stopped at a junction with a stop sign then answer 20 questions.
- 1/2 of each group were given questions implying the car stopped at a junction with the opposite sign, e.g. shown stopped at yield sign, implied stopped at stop sign.
- 20 minutes later they were shown 15 pairs of slides, select the correct one, the critical pair being of the stop or the yield sign.
- FINDINGS- 41% chose the correct slide with the misleading question.
- 75% chose the correct slide without the misleading question.
- A week later 20% chose correct on the misleading question.
- CONCLUSIONS- misleading information can replace true information from a scenario, called the misinformation effect.
- Independent groups design, so participants not suffer from order effects.
- deception used as participants were mislead.
Loftus and Palmer
- AIM- investigate the effects of leading questions on EWT accounts.
- PROCEDURE- 45 American students opportunity sample, shown brief car accident with a number of cars, asked to describe what happens.
- asked how fast the car was going when it- hit/smashed/collided/bumped/contacted eachother.
- a week later they were asked if they saw any broken glass, misleading as no glass in film.
- FINDINGS- the speed written was influenced by the verb used in the question, smashed had 41mph, hit had 34mph average.
- 32% said they saw glass a week later with smash, 14% with hit.
- CONCLUSIONS- EWT is easily affected by leading questions and is easily distorted.
- lab experiment, high control of variables.
- population bias, lack mundane realism- real life different emotional impact, film may contaion much less info than observing in real life.
- Anxiety- state of apprehension, worry, fear.
- experienced time of incident can affect accuracy of EWT
- occurs during encoding/aquisition stage of memory
- There are two different verdicts reached about anxiety and EWT, one from lab experiments and one from real life eyewitnesses.
- AIM- investigate the effects of anxiety on EWT (lab experiment)
- PROCEDURE- participants were exposed to one situation of the following:
- 1- overhear low key discussion in a lab, sound of equipement failure and man emerges holding pen with grease on his hands.
- 2- overhear heated exchange, sound breaking glass, smash chair, man emerges holding a paper knife covered in blood.
- They were then given 50 photos to identify the person who had emerged from the room.
- FINDINGS- in situation 1, 49% correctly identified the person.
- in situation 2, 32% correctly identified the person.
- CONCLUSIONS- When participants feel anxiety, they are less accurate at recalling events, and may focus on the weapon on the person holding it (weapon focus effect)
- high control lab expermient.
- results different to research using real life situations, deception used as participants not told the real nature of experiment.
Loftus and Burns
- AIM- Investigate the effects of anxiety on EWT
- PROCEDURE- participants either watched a non-violent film of a crime, or a violent film of a crime in which a boy was shot in the face.
- FINDINGS- participants who watched the violent film were much less accurate on recalling information about the crime.
- CONCLUSIONS- anxiety has a negative effect on EWT as it can cause less details to be remembered.
- high control, lack extraneous variables, reliable.
- lack of validitiy- real life situations different results, deception used, lack ecological validity, demand charactersistics, psychological harm of participants due to distressing images.
Yuille and Cutshall
- AIM- provide evidence of accuracy of EWT in real life events.
- PROCEDURE- 13 witnesses of a real life shooting- owner wounded but recovered, thief was shot dead, some witnessed the events close, others distant.
- FINDINGS- impressive accurate account several months later, closest gave most detail.
- misleading questions had no effect on the accuracy.
- The most distressed had most accuracy 5 months later, heightened awareness associated with anxiety enhanced accuracy of EWT.
- CONCLUSIONS- anxiety can improve the accuracy of EWT in real life situations
- used real life events, ecological vaildity, reduction of demand characteristics
- extraneous variables, psychological harm, not generalise to all crime types.
Christianson and Hubinette
- AIM- investigate the effects of anxiety on EWT accuracy in real life events.
- PROCEDURE- 110 witnesses, who between them had seen 22 genuine bank robberies asked to recall the events.
- Some onlookers, others directly threatened, e.g. staff etc.
- FINDINGS- victims more accurate than robbers wore, behaviour, weapons than bystanders.
- Superior recall continoued after 15 months interval.
- CONCLUSIONS- people are better at remembering stressful life events than artificial situations in a lab experiment.
- reduction of demand characteristics, real situation, easier to generalise.
- likelihood of behaviour needed slim, cannot generalise to all situations as speficic, loss of control, psychological harm as asked to recall stressful situations.
Age of Witness
- The age of the EWT can affect how accurate their account of a situation is.
- People also tend to recall the faces of people in their own age group better which could make their testimonies more or less accurate
Goodman and Reed
- AIM- investigate the effect of age on EWT
- PROCEDURE- 3 groups of participants, aged 3, 6, 22yrs old, recorded them for 5 mins with male adult stranger, asked questions and taught movements, 4-5 days later told not for motor learning but for EWT study.
- They were then asked questionnaire with leading questions, free-recall and identity of man from a line-up.
- FINDINGS- the younger participants were more suggestive to leading questions.
- The accuracy of free-recall increased with age.
- Line-up match was of 6-22yr olds was better than that of 3yr olds.
- Recall of false information minimal across all.
- CONCLUSIONS- accuracy of EWT increases across age, 3yr olds were the worst as they attended for less time, many wanted parents present/felt distressed, and limited language capabilities, may have been better if use props etc.
- high control lab experiment
- Deception used on participants, 3yr olds felt stressed
Kent and Yuille
- AIM- investigate the accuracy of child EWT
- PROCEDURE- group of children asked to chose a person they had interacted with earlier from a photo lineup.
- FINDINGS- 9yr olds more likely than older children to select from a photo display even if the person asked to identify is not present.
- Younger than 5yrs old can reliably identify unknown person brief intraction 2 days before from line up, but peform poorly if person not there, even when interact at length.
- CONCLUSIONS- young children capable of correct identification but find it difficult to admit they do not recognise anyone and respond to demand characteristics.
- High control lab experiment, show that young children can give accurate EWT
- younger children may have found experience stressful, consent from parents not them.
Poole and Lindsay
- AIM- investigate source missatribution in children and EWT
- PROCEDURE- children aged 3-8 watched a science demonstration, then listened to a story with some of the science in and some new information.
- Later questionned on what happened in the demonstration.
- FINDINGS- some of the children added details from the story to the science experiment
- Later when asked where the information came from, older children mostly do successfully, but younger children had poor source recognition, less able to distinguish source.
- CONCLUSIONS- younger children have poor source recognition and are unlikely to make good EWT due to this.
- high control lab experiment, lack extraneous variables.
- Consent from parents not children, 3yr olds may have been worse as have limited language.
Flin et al.
- AIM- Investigate the effect of age on EWT
- PROCEDURE- interviewed children and adults 1day then 5months after an incident.
- FINDINGS- no difference in accuracy between the children/adults after 1 day, but after 5months, children were less accurate in detail than adults.
- CONCLUSIONS- This has implications for EWT as often there are long delays between crime and proceedings in which the details of the event could be forgotten by the EWT
- children unable give fully informed consent, given by parent
Ceci and Bruck
Drew conclusions and made recommendations for EWT and children:
- Preschool age children capable relevant EWT, but more suggstible than older children, who are more suggestible than adults.
- exposed leading questions/misleading information techniques can cause peripheral details and central gists of events wrong.
- should be audio/video taped from first interview onwards.
- much evidence rom lab experiments, lack validity, ethically imposibble make lab studies as intense/distressing as real life situation for some children.
- Responsibility involved in collect/evaluate EWT knowledge and factors can affect accuracy of it.
There are many things that can affect recall e.g.:
- interview bias, repeated questions, stereotypes, encouragement to visualise, peer pressure, authority figures.
Cohen and Faulkner
- AIM- investigate the effects of age on EWT.
- PROCEDURE- film of kidnapping shown to a group of middle aged and elderly participants.
- Read a narrative of what just witnessed, groups split again:
- 1/2 read narrative consistent with what they saw.
- 1/2 read narrative inconsistent with what they saw. (misleading information)
- FINDINGS- in recall test, elderly particiants were more susceptible to the effects of misleading information than the middle aged participants.
- CONCLUSIONS- elderly people could make unreliable EWT as they are more suggestible.
- high control lab experiment
- demand characteristics, some participants mislead (make them uncomfortable).
Anastasi and Rhodes
- AIM- Investigate the effects of age on identifying people in a photo lineup.
- PROCEDURE- Compared 3 age groups spread across 18-78 in ability to recall photos people previously seen.
- Photos of all 3 age groups used on all 3 age groups.
- FINDINGS- young/middle aged more accurate overall with the recall than elderly participants.
- All 3 groups peformed best when tested photos on own specific age group. (own age bias)
- CONCLUSIONS- elderly people can make less reliable EWT, but people are better at identifying people in their own age group.
- high control lab experiment
- lack ecological validity
Improving accuracy of EWT- Fisher et al
- Aimed to investigate the accuracy of EWT.
- Recalled the interviews experienced detecives in Florida for 4 month period.
- Witness bombarded with series brief, direct questions, close ended, elicit faster.
- Sequencing out of sync with memory representation of event.
- not allowed talk freely about experiences, breaks concentration.
- encourage shorter, less detailed answers.
The Cognitive Interview
- Designed by Geiselman et al for use in police investigations. There are 4 steps used:
- Context reinstalment (CR)- not revise crime itself, look at setting-weather, lighting, smells, people around.
- Report Everything (RE)- report all information from the event can remember, even if not to do with the crime.
- Recall from changed perspective (CP)- describe from other people who were present.
- Recall in reverse order (RO)- start aspect most memorable, work back from that point.
- AIM- effectiveness of cognitive interview (CI) compared to standard techniques.
- PROCEDURE- police training film violent crime to 89 students, 48hrs later interviewd by police with standard or CI, each taped/analysed for accuracy.
- FINDINGS- CI standard
- correct 41.5 29.4 error rates similar but considerably
- incorrect 7.3 6.1 more remembered with CI.
- confabulated 0.7 0.4
- lab experiment, independent groups design.
- demand characteristics, population/cultural bias.
Milne and Bull
- Aimed to look at the effectiveness of the CI.
- When the parts of the interview were used individually, there was little gain over the standard interview techniques used.
- Only when two or more components are used is there a significant improvement in recall.
Kebbell et al.
- Conducted a survey of police officers in the UK and found there was widespread use of the CI, but while the officers found it useful, they showed concern over the amount of incorrect recall generated and the amount of time necessary to complete an enhanced CI.
- In practice seemed officer rarely used the CP and RO instructions, but used RE and CR more.
CI on children
- Geisleman- number of studies childern under 6 slightly less accurate with the CI, instructions difficult for them to understand, effective for 8yrs +
- Holliday- modified the CI for children, 2 groups 4-5yr olds and 9-10yr olds, shown 5 min video of a birthday, 1 day later they were interviewed with standard or CI.
- They showed more correct recall on CI than standard.