Forensics (need to complete L6) Flashcards
Forensic Psychology
Application of psychological knowledge and theories to all aspect of the criminal and civil justice system
History of Forensic Psychology
- James Cattell (1895) - recall things they witnessed in their everyday life
- Afred Binet (1900) invented the intelligence test
- Varendonck (1911) was called to be an expert witness: 84% of children’s said a colour when the teacher didn’t have a beard, hence inaccurate
- Eyewitness Research: People were not accurate
Functions of an Expert Witness (important)
- Aid in understanding a particular issue relevant to the case
- Allowed to express their opinion
Challenges of Providing Expert Witness
- Lack ecological validity
- Psychologist may become advocates and lose their objectivity
Admissibility Criteria
- Experts must satisfy judge
- Experts have special knowledge above and beyond that of average juror
- R vs Turner 1975: Just because experts are well qualified does not mean they are helpful to the jury
Expert Evidence
- Fingerprints
- Facial Mapping
- Hair analysis
Estimator Variables
- Variables that are present at the time of the crime and cannot be changed
- E.G. lighting at the event, characteristics of witness
Estimator Variables: FLASHBULB MEMORY
- When we experience a traumatic experience, we have a vivid memory
- But memory degrades overtime. E.G. Holocaust survivors who have vivid memories make mistakes in their perpetrators
Estimator Variables: YERKES-DODSON LAW
- Emotional Levels
- Memory best at optimum level of arousal
Easterbrook Hypothesis
- Strong memorise for central details
- Poor memory for peripheral details
- E.G. more alert after hearing a gunshot
System Variables
- Variables that can be manipulated afterwards and impact the accuracy of witnesses
- E.G. The way police question a witness
Misinformation Effect/False Memory
Exposure to incorrect information about an event after it has occurred often causes people to incorporate this misinformation into their memories
- Loftus
- Loftus and Palmer
Loftus and Pickrell (1995)
- Gave participants narratives of being “Lost for an extended time in a shopping mall at age 6 and rescued by an elderly person”
- 25% reported being lost in a mall and gave rich and vivid details
Wade et al (2002)
- Participants were shown a fake print advertisement that described a visit to Disneyland and how they met and shook hands with Bugs Bunny.
- Later, 16% reported meeting and shaking hands with Bugs Bunny
Williams (1994)
- Interviewed 129 women how bad childhood sexual abuse
- 38% of the women did not report any abuse
Implications of Misinformation Effect
Ask open and non-leading questions
Factors increasing susceptibility to the misinformation effect
- Age
- Hypnosis
- Detail is peripheral
Target-Present Lineups
- Lineup contains culprit
- To correctly identify culprit to prove guilty
Target-Absent Lineups
- Lineup does not contain culprit
- To correctly reject all lineup members to prove suspect innocence
How do we know ID evidence is inaccurate
- Surveyed Justice Officials
- DNA Exoneration Cases
- Empirical studies of ID performance
- Surveyed Justice Officials
Over 70% thought that erroneous convictions occurred in less than 1% of the cases
- DNA Exoneration Cases
- Link a person to a crime with a high degree of certainty
- In 2015, 72% of DNA exoneration were due to mistaken identification
- Empirical studies of ID performance
a. Field Studies: high in ecological validity but lack experimental control
b. Laboratory Studies: allow more control but lack ecological validity
Piggott et al., (1990)
- Confederates go into banks and perform an unusual transaction
- Bank teller’s falsely identified 35.8% of IDs
Wells, (1993)
- Participants watch staged crime and required to identify the perpetrator lineup
- False ID varied from about 0% to about 100%
Factors Affecting Estimator Variables
- Viewing conditions
- Fatigue
- Own race bias
Factors Affecting System Variables
- ID procedures
- Composition of lineup
- Instructions given to witnesses
Identification Procedures
- Showups
- Lineups
Identification Procedures: SHOWUPS
- One person lineup containing only the suspect
- Only acceptable if not enough evidence to arrest and conduct lineup
Identification Procedures: LINEUPS
- Ability of the witness to identify the suspect when seen with several foils
Composition of ID Procedure
- Lineup should consist of foils who look like the eyewitness’s description
Format of ID Procedure
- Photo-lineups
- Mugshot Searches: witness sees a face in a mugshot search is likely to pick that person out in a lineup, even if not the culprit due to unconscious transference
Unconscious Transference
- When people remember a face, but mistake the circumstances in which they saw the face
- E.G. Robert Clark
Instructions Given
- Witness should be told that suspect may or may not be in the lineup
- E.G. Police officer officer who knows suspect might unintentionally looking carefully at a particular suspect and witness notices
Lineup Presentation
- Simultaneous Lineup
- Sequential Lineup
- Lineup Presentation: SIMULTANEOUS LINEUP
All lineup members are presented at the same time
- Lineup Presentation: SEQUENTIAL LINEUP
Members are presented one at a time and must decided if is or is not the criminal before seeing another photo
- a. Sequential Lineup: RELATIVE JUDGEMENT
- Comparing lineup members to other lineup members
- b. Sequential Lineup: ABSOLUTE JUDGEMENT
- Comparing lineup members to witness’ memory
Simultaneous vs Sequential
- Sequential lineups were less likely to identify guilty or not guilty
- When a suspect was identified, they were more likely to be guilty when using sequential
Robbery-Murder Case
- Circumstantial Evidence
- Circumstantial Evidence + eyewitness testimony
- Circumstantial evidence + discredited eyewitness