Forensic psychology
Week 1
Eye-witness testimony:
Apply psychology to crime and law
Areas of practice:
•Police and public safety
•Legal psychology
•Psychology of crime and delinquency
•Victimology and victim services
•Correctional psychology
Eyewitness testimony:
•Witness evidence have an important role in police investigations, irrespective of its
validity
•Particularly problematic in circumstances in which the witness and the offender are
strangers
•Eyewitness misidentification is the greatest contributing factor to wrongful
convictions
•Many cases have been overturned through DNA testing/DNA-based exornerations.
Example: EYEWITNESS TESTIMONY:
A MURDER IN ALASKA
•A 1997 murder case in Alaska involving the murder of a teenage boy, resulted in the
arrests of 4 suspects, 2 of whom were tried for their crimes.
•The centerpiece of the prosecution’s case was the testimony of Arlo Olson, who,
while drunk, had seen the perpetrators at night and from a distance of 450 ft (≈
137m).
•Olson picked the defendants from photographic line-ups, despite perceptual
disadvantages.
IDENTIFICATION PROCEDURES
May include mugshot, lineup, photo array and in-court identification.
•Show-up procedures
•A witness is presented with a single suspect and asked, ‘Is this the person you saw
commit the crime?’ typically happens in crime scene.
•Line-up procedure (identification parade)
•The suspect and 5 ‘fillers’ are shown to the witness, who decides which, if any, of
the line-up members is the perpetrator
A key challenge is to administer an identification procedure that is unbiased
,CULPRIT-PRESENT VS CULPRIT-ABSENT
LINE-UPS
•Culprit-absent line-ups problematic for eyewitnesses
•How do eyewitnesses choose the culprit from the line-up?: Relative judgement
theory: In the absence of a culprit, the line-up members most similar to the culprit
will be picked out, even if the person who commited a crime is absent.
ESTIMATOR VARIABLES
•Something which affects the accuracy of the eyewitness but is not within the powers
of the criminal justice system to influence
•E.g., age of the eyewitness, how close the witness and the offender were at the
crime scene, lighting conditions at the time of witnessing, whether the witness and
the offender are of the same or different races
•Four broad categories
•Characteristics of the witness
•Characteristics of the event
•Characteristics of the testimony
•Abilities of the testimony evaluators to discriminate between accurate and
inaccurate witness testimony
CHARACTERISTICS OF THE WITNESS:
RACE
•Own-race bias (cross-race effect/other-race effect)
•People are better at discriminating faces of their own race/ethnic group than faces
of other races/ethnic group (Meissner & Brigham, 2001)
•Infants as young as 6 months old exhibit ORB (Xiao et al., 2018).
•Cross-racial identification
•Can hinder eyewitness description effectiveness, testimony, and identification –
“they all look alike”
INTERPRETATIONS OF OWN-RACE BIAS
•Racial attitudes related or not? (Meissner & Brigham, 2001; Vitriol et al., 2019)
•Racial bias → group differentiation → categoristion
•In-group/out-group model: Witnesses use a more liberal criterion with other-race
faces than with own-race faces? (Doyle, 2001)
•Other issues…
•How do people end up in lineups in the first place?
•Strategic colourblindness potentially hinders eyewitness testimony? (Egan,
Gilzeane, & Viskaduraki, 2011)
CHARACTERISTICS OF THE EVENT:
PRESENCE OF A WEAPON
, •Weapon-Focus Effect
•The presence of a weapon draws attention toward the weapon and away from the
weapon-holder's face (and other details of a criminal event), influencing the reliability
of eyewitness reports (Steblay, 1992).
•Why does a weapon attraction attention?
•Weapon focus is diminished when the weapon is anticipated on the basis of the
environment (Fawcett, Peace, & Greve, 2016), or due to prior knowledge of the
person holding the gun (Pickel, 2009)
•Weapon-focus effect may occur because the presence of a weapon is unexpected
rather than because it is threatening
•Witnesses are more likely to commit false identifications when a weapon was
involved in a mock crime
•Individuals exposed to weapons are also more susceptible to false information –
e.g., through leading questions or exposure to police suspects (Saunders, 2009)
CHARACTERISTICS OF THE TESTIMONY:
WITNESS CONFIDENCE
•Elizabeth Loftus (1979): “There is almost nothing more convincing than a live
human being who takes the stand, points a finger at the defendant, and says “That’s
the one!”
•There is little to no relationship between accuracy and confidence of eyewitnesses
(Smith, Kassin, & Ellsworth 1989) – traditionally used procedures
•BUT… when pristine procedures are used, confidence can be highly indicative of
accuracy, according to lab and field data (Wixted & Wells, 2017).
•A confidence statement should be collected at the time of the identification.
CHARACTERISTICS OF THE TESTIMONY:
LAY OBSERVERS’ JUDGEMENT OF ACCURACY
•Suggestive post-identification feedback can influence evaluators’ abilities to
discriminate between accurate and inaccurate eyewitness (Smalarz & Wells, 2014)
•No feedback – testimony evaluators were more likely to believe the testimony of
accurate eyewitnesses
•Confirming feedback: “Good job! You identified the suspect.” – evaluators believed
accurate and mistaken witnesses at nearly identical rates
SYSTEM VARIABLES
Week 1
Eye-witness testimony:
Apply psychology to crime and law
Areas of practice:
•Police and public safety
•Legal psychology
•Psychology of crime and delinquency
•Victimology and victim services
•Correctional psychology
Eyewitness testimony:
•Witness evidence have an important role in police investigations, irrespective of its
validity
•Particularly problematic in circumstances in which the witness and the offender are
strangers
•Eyewitness misidentification is the greatest contributing factor to wrongful
convictions
•Many cases have been overturned through DNA testing/DNA-based exornerations.
Example: EYEWITNESS TESTIMONY:
A MURDER IN ALASKA
•A 1997 murder case in Alaska involving the murder of a teenage boy, resulted in the
arrests of 4 suspects, 2 of whom were tried for their crimes.
•The centerpiece of the prosecution’s case was the testimony of Arlo Olson, who,
while drunk, had seen the perpetrators at night and from a distance of 450 ft (≈
137m).
•Olson picked the defendants from photographic line-ups, despite perceptual
disadvantages.
IDENTIFICATION PROCEDURES
May include mugshot, lineup, photo array and in-court identification.
•Show-up procedures
•A witness is presented with a single suspect and asked, ‘Is this the person you saw
commit the crime?’ typically happens in crime scene.
•Line-up procedure (identification parade)
•The suspect and 5 ‘fillers’ are shown to the witness, who decides which, if any, of
the line-up members is the perpetrator
A key challenge is to administer an identification procedure that is unbiased
,CULPRIT-PRESENT VS CULPRIT-ABSENT
LINE-UPS
•Culprit-absent line-ups problematic for eyewitnesses
•How do eyewitnesses choose the culprit from the line-up?: Relative judgement
theory: In the absence of a culprit, the line-up members most similar to the culprit
will be picked out, even if the person who commited a crime is absent.
ESTIMATOR VARIABLES
•Something which affects the accuracy of the eyewitness but is not within the powers
of the criminal justice system to influence
•E.g., age of the eyewitness, how close the witness and the offender were at the
crime scene, lighting conditions at the time of witnessing, whether the witness and
the offender are of the same or different races
•Four broad categories
•Characteristics of the witness
•Characteristics of the event
•Characteristics of the testimony
•Abilities of the testimony evaluators to discriminate between accurate and
inaccurate witness testimony
CHARACTERISTICS OF THE WITNESS:
RACE
•Own-race bias (cross-race effect/other-race effect)
•People are better at discriminating faces of their own race/ethnic group than faces
of other races/ethnic group (Meissner & Brigham, 2001)
•Infants as young as 6 months old exhibit ORB (Xiao et al., 2018).
•Cross-racial identification
•Can hinder eyewitness description effectiveness, testimony, and identification –
“they all look alike”
INTERPRETATIONS OF OWN-RACE BIAS
•Racial attitudes related or not? (Meissner & Brigham, 2001; Vitriol et al., 2019)
•Racial bias → group differentiation → categoristion
•In-group/out-group model: Witnesses use a more liberal criterion with other-race
faces than with own-race faces? (Doyle, 2001)
•Other issues…
•How do people end up in lineups in the first place?
•Strategic colourblindness potentially hinders eyewitness testimony? (Egan,
Gilzeane, & Viskaduraki, 2011)
CHARACTERISTICS OF THE EVENT:
PRESENCE OF A WEAPON
, •Weapon-Focus Effect
•The presence of a weapon draws attention toward the weapon and away from the
weapon-holder's face (and other details of a criminal event), influencing the reliability
of eyewitness reports (Steblay, 1992).
•Why does a weapon attraction attention?
•Weapon focus is diminished when the weapon is anticipated on the basis of the
environment (Fawcett, Peace, & Greve, 2016), or due to prior knowledge of the
person holding the gun (Pickel, 2009)
•Weapon-focus effect may occur because the presence of a weapon is unexpected
rather than because it is threatening
•Witnesses are more likely to commit false identifications when a weapon was
involved in a mock crime
•Individuals exposed to weapons are also more susceptible to false information –
e.g., through leading questions or exposure to police suspects (Saunders, 2009)
CHARACTERISTICS OF THE TESTIMONY:
WITNESS CONFIDENCE
•Elizabeth Loftus (1979): “There is almost nothing more convincing than a live
human being who takes the stand, points a finger at the defendant, and says “That’s
the one!”
•There is little to no relationship between accuracy and confidence of eyewitnesses
(Smith, Kassin, & Ellsworth 1989) – traditionally used procedures
•BUT… when pristine procedures are used, confidence can be highly indicative of
accuracy, according to lab and field data (Wixted & Wells, 2017).
•A confidence statement should be collected at the time of the identification.
CHARACTERISTICS OF THE TESTIMONY:
LAY OBSERVERS’ JUDGEMENT OF ACCURACY
•Suggestive post-identification feedback can influence evaluators’ abilities to
discriminate between accurate and inaccurate eyewitness (Smalarz & Wells, 2014)
•No feedback – testimony evaluators were more likely to believe the testimony of
accurate eyewitnesses
•Confirming feedback: “Good job! You identified the suspect.” – evaluators believed
accurate and mistaken witnesses at nearly identical rates
SYSTEM VARIABLES
