factors affecting eyewitness testimony

• what is eyewitness testimony?

  • legal term
  • refers to evidence given in court room or in a police investigation by someone who has witnessed/heard a crime/accident
• wells 1998?

  • studied 40 people who were convicted & later released as a result of dna evidence
  • more than 90% were wrongfully convicted due to ewt evidence
• 2 factors affecting accuracy of ewt?

  1. misleading info - leading questions & post event discussion
  2. anxiety
• define misleading info?

  • incorrect info given to an eyewitness following an event
• what are leading questions?

  • a question in which because of the way its phrased suggests a certain answer & thus leads to the individual to answer in that way
• loftus & palmer 1974 car crash study?

  • used 45 participants
  • split into 5 groups
  • were shown 7 vids of cars colliding
  • after watching each vid all participants were asked "about how fast were the cars going when they ... each other?"
  • each group was given a different verb to fill in blank
• 5 verbs used in loftus & palmer study?

  smashed

  collided

  bumped

  hit

  contacted
• loftus & palmer car crash findings?

  • how the question was phrased influenced participants speed estimates misleading them to give incorrect estimates of recalled event
  • smashed - 40.8 mph
  • collided - 39.3 mph
  • bumped - 38.1 mph
  • hit - 34 mph
  • contacted - 31.8 mph
  • when "smashed" was used participants estimates were much higher than when "contacted" was used
• loftus & palmer 1974 alteration of memory study?

  • investigated if wording of question has ability to change memory
  • used 150 participants
  • split into 3 groups
  • participants were shown a short film that showed multi vehicle car accident
  • were then asked questions about it
• loftus & palmer alteration of memory method?

  g1 - how fast were the cars going when they hit each other?

  g2 - how fast were the cars going when they smashed into each other?

  g3 - not asked about speed

  one week later all participants were asked "did you see any broken glass?"

  THERE WAS NO GLASS
• loftus & palmer alteration of memory findings?

  • found that participants in 2nd group who had originally heard "smashed" were more likely to report seeing broken glass
• what is post event discussion?

  • occurs when there is more than one witness to an event by which witnesses disscuss what they have seen with each other
  • this influences accuracy of each persons recall of event
• gabbert et al 2003 study?

  • investigated effect of ped on accuract of ewt
  • sample consisted of 60 students & 60 older adults
  • participants independently watched video of girl stealing money from wallet
  • then were tested individually or as pairs (co witness)
• gabbert et al 2003 method?

  • participants in co witness were told they watched same vid as partner but had seen it from different angle so had different perspective of crime
  • participants in co witness group discussed crime together & all were asked to complete questionnaire testing memory of event
• gabbert et al 2003 findings?

  • 71% of witnesses in co witness group went on to mistakenly recall info they had acquired from discussion & not actually seen
  • 60% said girl was guilty despite not having seen her commit crime
  • results highlight the issue of ped & powerful effects this can have on accurary of ewt
• 2 * of misleading information?

  1. evidence to support belief that misleading info is a factor affecting ewt from loftus
  2. practical uses in real world
• 3 X misleading information?

  1. research is artificial
  2. ewt can be affected by own age bias - anastasi & rhodes 2006
  3. evidence to suggest ewt influenced by demand characteristics from zaragosa & mccloskey 1989
• * evidence to support that m i is factor affecting ewt explain?

  • loftus asked p to take part in ad evaluation program
  • all visited disneyland/disneyworld
  • were split into 4 groups & read printed ad for dl
  • g1 - no mention of cartoons in ad
  • g2 - same ad with 4ft tall cardboard cutout of bugs bunny was placed in room
  • g3 - fake ad featuring bb
  • g4 - both fake ads & in room with cutout
  • bugs not mentioned in dl as its part of warner bros
  • p had to recall if they had met bb or shook hands with him
  • 40% claimed they saw/shook hands with him
• evidence to support mi is factor affecting ewt conclude?

  * valid - results demonstrate that presence of incorrect info can mislead & impact participants ability to accurately recall an event they experienced
• * practical uses in real world?

  • as a result of her findings loftus believes leading questions can have distorting effect on memory that police officers need to be very careful about how they phrase questions when interviewing witnesses
  • * ecological
  • research into leading questions has allowed police to develop new interviewing techniques which avoid language that may affect certain answers
  • overall leads to more accurate recall in court
  • can have further economic implications for society by reducing amount of wrongful convictions
• X artificial research?

  • participants in loftus & palmer watched clips of car accidents
  • this is very different experience from witnessing a real accident as watching a vid is less emotionally arousing than witnessing it in real life
  • ? ecological
  • artificial materials used to study these factors may not provide us with accurate representation of how our memory would be influenced in recall of real events
  • difficult to generalise findings to real life situations of ewt
• X affected by own age bias?

  • anastasi & rhodes 2006 investigated individuals from 3 diff age groups were shown photos & asked them to rate on attractiveness
  • 18-25 35-45 55-78
  • were later given photo recognition task & asked to identify faces that they have already seen & rated earlier on
  • all age groups were accurate identifying faces from own age groups
  • suggests presence of misleading info is not only factor which impacts accuracy of ewt
  • may be other factors
• X evidence to suggest ewt influenced by dc?

  • zaragosa & mccloskey 1989 argue that many answers participants given in lab studies of ewt are result of dcs
  • do not want to let researcher down & want to appear helpful/attentive when trying to recall events of crime
  • when asked a question they dont know anwer to may guess especially at yes/no question
  • ? internal
  • hard to tell if participant is behaving naturally
  • means it is difficult to generalise findings to real life explanations of factors that affect accuracy of ewt
• what is the weapon focus effect?

  • during violent crimes increased arousal (anxiety) may cause a witness to focus more on central details of attack
  • e.g presence of weapon rather then peripheral details leading to poor & inaccurate recall of details in violent crimes
• effect of anxiety on ewt?

  • has strong physical & emotional effects
  • not clear whether these effects would make eyewitnesses recall better or worse
• johnson & scott 1976 negative effect?

  • led p to believe that they were going to be taking part in lab experiment
  • while seating in waiting room p heard an argument in adjoining room
• johnson & scott 1976 method?

  • low anxiety condition - discussion was heard followed by a man leaving room with a pen & grease on hands
  • high anxiety condition - heated discussion was heard accompanied by sound of breaking glass & man leaving room holding pen knife & hands covered in blood
• johnson & scott 1976 findings?

  • low anxiety condition - 49% accurate
  • high anxiety condition - 33% accurate
  • shows that when participants in condition 2 saw knife presence of weapon caused them to be more anxious & as a result focused on details of weapon rather than identifying perpetrator
• yuille & cutshall 1986 positive effect?

  • conducted study of real life shooting in gun shop in canada
  • shop owner shot thief dead
  • were 21 witnesses & 13 agreed to take part
  • interviews were held 4/5 months after incident & these were compared with original police interviews at time of shooting
• yuille & cutshall 1986 method?

  • using 7 point scale on questionnaire witnesses were asked to rate how stressed they felt at time of incident & if had any emotional problems since then(ptsd, lack of sleep)
  • p were very accurate in their accounts & there was little change 5 months after
• yuille & cutshall 1986 findings?

  • p who had reported highest levels of stress were more accurate - 88%
  • less stressed p - 75%
  • shows that presence of stress can be a useful factor in improving accuracy of ewt as p who had high level of anxiety were more alert & thus paid more attention to details of event & as a result had most accurate recall
• explain yerkes-dodson law 1908?

  • relationship between emotional arousal & accuracy is not a single one
  • if anxiety too high/too low accuracy is poor
  • an increase in anxiety improves performance as become more alert but only upto a certain point
  • once arousal has passed optimum accuracy tends to decline
• 5 X of research into anxiety?

  1. evidence to contradict weapon focus effect from pickel 1998
  2. ethical issues surrounding research
  3. influenced by individual differences - bothwell et al 1987
  4. yerkes-dodson law too simplistic
  5. evidence to suggest ewt influenced by dcs
• X evidence to contradict weapon focus effect?

  • j & s study may actually test element of surprise rather than anxiety
  • p focus on weapon as they are surprised by what they see not always because are scared/anxious
  • pickel 1998 conducted study where thief entered hairdressing salon carrying scissors,handgun,wallet,raw chicken as random items
  • found ewt was poor in high unusualness conditions
  • shows presence of unusual items are just as significant in influencing accuracy of ewt
  • meaning cannot be sure if its anxiety which makes us focus on weapon or if its just we are shocked to see it
• X ethical issues?

  • ethical issues of protection from psychharm may be broken as research is creating anxiety in participants purely for purpose of research
  • p are experiencing more harm than they would in real life meaning it would be difficult to replicate these studies in future to check for reliability
  • may be more ethical ways to conduct research into this area
• X influenced by individual differences?

  • in bothwell et al 1987 study p were assessed for neuroticisim - personality trait where individuals tend to become anxious quite quickly
  • p tested & labelled as neurotic/stable
  • stable p showed rising levels of accuracy as stress levels increased but opposite for neurotics - accuracy decreased as stress increased
  • shows there are individual differences in way levels of arousal impact accuracy of ewt depending on our personality type
  • not a consistent explanation that can be applied to recall accurately in entire population
• X yerkes-dodson law too simplistic?

  • anxiety is difficult to define & measure accurately
  • has many elements - cognitive/behavioural/emotional/physical
  • inverted u explanation assumes only one of these is linked to poor performance - physical arousal
  • suggests that only physical arousal has an impact but anxiety has multiple components which have not been considered so may be other aspects to anxiety which increase/decrease accuracy of ewt
• X evidence to show ewt influenced by dcs?

  • most lab studies showed p a filmed/staged crime
  • these p were aware they are watching a filmed crime for a reason to do with study
  • chances are most will work out what questions are going to be asked about what they have seen meaning will guess aim of study & change behaviour accordingly
  • ? ecological
  • rm involved are prone to dcs
  • behaviour is unlikely to be natural meaning its difficult to generalise findings to real life explanations of how anxiety influences ewt