eyewitness identification

Question 1

eyewitness identification

Answer 1

• testimony of a witness regarding their direct observations during an event, when the identity of a person involved is at issue
• recognition evidence regarding the identity of a person involved in an incident

Question 2

encoding factors

Answer 2

• attention-focus model: high arousal will positively impact the encoding of some aspects of an event (ie. central details) while negatively impact the encoding of others (ie. peripheral details), consistent with easterbrook, very high levels of arousal may narrow the focus to a level vs as a whole
• viewing distance and time
• weapons focus

Question 3

signal detection theory

Answer 3

• witness compares the person to their memory of the offender
• based on this comparison, decides whether to identify the person as the offender or not
• if the person matches their memory above a certain decision criterion, the witness will identify the suspect as the offender

Question 4

signal detection theory con’t

Answer 4

• both guilty and innocent people will match the witness’ memory to varying extents
• some innocent people will match very well
• some guilty people will not match well due to errors in memory storage or retrieval

Question 5

signal detection theory con’t 2

Answer 5

• ability to discriminate between the witnessed offender and an innocent person depends on the overlap in how well they each match the person’s memory
• changing diagnostic criteria does not reduce the errors, but changes the type of errors made
• increase decision criterion = reduce false and correct identification rate
• decrease decision criterion = increase correct and false identification rate

Question 6

identification process: show up

Answer 6

• single suspect shown to witness, at which time they will provide a judgement of whether that person is the offender
• may occur shortly after a crime, such as when a person is observed near the scene who fits the description

Question 7

identification process: lineup

Answer 7

• presented with a suspect, along with fillers (people who are innocent)
• match fillers to the suspect (not necessarily to the description of the offender)
• blind lineup administration
• instructions: the person who committed the crime may or may not be present, eyewitnesses not required to make an identification

Question 8

biased vs. unbiased instructions

Answer 8

• nyman et al hostage situation
• ecologically valid
• the rate of correct decisions (identification or non-identification) was higher with unbiased instructions
• biased instructions decreased the decision criterion (but more people identified, including guilty)
• unbiased instructions increased the decision criterion

Question 9

identification process: lineup (canada)

Answer 9

• in canada, this is typically presented sequentially (rather than previously common simultaneous presentation of a suspect and fillers)

Question 10

show up vs. lineup

Answer 10

• research since 1993 has found: higher false identification rates (compared to lineups), correct identification rates are equal to lineups
• eisen et al compared showups and lineups in the field, where participants believed an identification would lead to an arrest: showup decisions went up, lineup decisions went down

Question 11

eyewitness confidence

Answer 11

• eyewitness identification confidence a the time of initial identification is related to accuracy
• later confidence in eyewitness identification weakly or not, related to accuracy (memory may be distorted)
• biased instructions tend to inflate confidence)

Question 12

accuracy of identification (short & dalby)

Answer 12

• participants identified the offender they had seen commit a theft in a video
• asked what led them to select a person and mental images mentioned in the post-identification were probed for details
• content analysis of post-identification statements resulted in correctly classifying identification as accurate or inaccurate 70% of the time
• accurate identification accompanied by statements that are low on quality of description and high on amount of detail

Question 13

decision making with identification

Answer 13

• the use of experts in court to educate on the fallibility of eyewitness memory is viewed as redundant and unnecessary (caution by trial judge is used to deal with risk of eyewitness misidentification)
• jurors or judge need to determine how much weight to give identification in their decisions

Question 14

canadian recommendations for lineups

Answer 14

• only use show ups in exceptional circumstances
• double blind
• witness instructions
• filler selection
• sequential presentation
• lineup size (10 people maximum)