7. EWT misleading information

EWT definition

the ability of people to remember the details of events which they themselves have observed

can be affected like factors such as misleading information and anxiety

misleading information

• incorrect information given to an eyewitness usually after the event

• can take many forms including

  1. leading questions

  2. post event discussion

leading questions

a question which, because of the way its phrased, suggests a certain answer

procedure

loftus & palmer

• arranged 45 participants (students) to watch film clips of car accidents and then asked them questions about it

• in the critical question they were asked to describe how fast the cars were travelling

• five groups and each group was given a different verb in the critical question (hit, contacted, bumped, collided, smashed)

findings

• mean estimated speed was calculated for each group

• contacted - 31.8 mph

  smashed - 40.5 mph

why do leading questions affect EWT

• response-bias explanation suggests the wording has no real effect on their memories, but simply influences how they decide to answer - ie smashed encourages a higher speed estimate

• lofter palmer conducted a second experiment supporting the substitution explanation, proposing the wording changes their memory - those who heard smashed were later more likely to report seeing glass (there was none) than those who heard hit

post event discussion (PED)

• occurs when there is more than one witness to an event

• witnesses may discuss what they have seen which can influence the accuracy of each witness’s recall of the event

procedure

gabbert et al

• studied participants in pairs

• each participant watched a video of the same crime but filmed from different POVs - meant each participant could see elements that the other could no

• then discussed what they had seen before individually completing a test of recall

findings

• found 71% mistakenly recalled aspects of the event that they did not see in the video but picked up in PED

• corresponding figure in control group where there was no discussion was 0%

evidence of memory conformity

why does PED affect EWT

two explanations

1. memory contamination - when witnesses discuss a crime with each other, their EWT may become altered or distorted as they combine (mis)information from other witnesses with their own memories

2. memory conformity - gabbert et al concluded witnesses often go along with eachother either to win social approval or as they believe the others are right and they are wrong

unlike memory contamination, actual memory is unchanged

evaluation

1. real world application

2. high internal validity

3. low ecological validity

4. evidence against substitution

5. explanatory power

real world application

• research on misleading information has practical uses in the criminal justice system

• loftus found leading questions can distort eyewitness memory - police officers need to be careful when phrasing questions to witnesses and psychologists now help courts to understand the limits of EWT

• helps improve the legal system by preventing wrongful convictions based on unreliable EWT

high internal validity

• both studies conducted in controlled lab settings allowing the isolation of variables to establish causation

• high levels of control and replicability strengthens argument misleading information can distort EWT

low ecological validity

• EWT research has limitations as studies often occur in artifical settings

• loftus & palmer study used film clips which lack the stress of real life situations - may mean the effect of misleading information is overstated in lab research

• gabbert - knew in study so paid close attention to details in video clips

• research by FOSTER ET AL found eyewitnesses were more accurate when they believed the event was real and that their responses mattered 

• suggests researchers are too pesimistic about effects of misleading information as EWT may be more dependable than many studies suggest

evidence against substitution

• some aspects of memory are more resistant to misleading information than others

• sutherland & hayne found participants memory for central details of an event was more accurate than for peripheral details - suggests original central memories survive despite misleading information, contradicting the substitution explanation

• not all memory is equally vulnerable to distortion meaning the impact of misleading information may be overstated

demand charectaristics

• lab studies on misleading information may be affected by demand charectaristics

• psychologists argue participants guess answers to appear helpful so if they are trying to please researchers the results may not reflect real life memory processes

• questions validity of lab based EWT research suggesting real world effects may differ

explanatory power

• gabbert could not explain why the effects of PED occurred so the memory distortion could be due to

1. pressure to conform to other eyewitnesses

2. poor memory so unable to distinguish