Document 15113780

: L0472 - Psikologi Forensik
: Feb -2010
Techniques of Criminal Investigation II
Pertemuan 04
Techniques of Criminal
Investigation II
Reza Indragiri Amriel
Police Interrogations & Confessions
• Would you confess to a crime you did not commit?
• 347 students were asked this question:
– Yes – I might confess – 2.6%
– No – I would not – 63%
– My answer depends – 34%
• Men: 43%
Women: 31%
– People usually overestimate their ability to resist to coercion.
Police Interrogations & Confessions
• Kassin’s study: 75 subjects
• Reaction-time experiment – make sure not to hit the ‘alt’ key or the
program will crash.
– At first all denied
– 50% were accused by a witness
• Given a choice: sign a confession or meet the
professor --- all signed the confession
• On their way out meet another confederate who
asks what happened: 66% admitted to having
crashed the program!
Eyewitness Accuracy
Research on Wrongfully Convicted Defendants
Wells et al. (1998)
– Studied 40 people who were convicted but later
cleared by DNA
– In 90% (36) of the cases, there was false
eyewitness identification
Rattner (1988)
Brandon and Davies (1973)
– Studied 205 wrongfully convicted defendants
– 52% were due to inaccurate eyewitness testimony
– Book described 70 cases of people wrongfully
convicted due to inaccurate eyewitness testimony
Eyewitness Accuracy
Buckhout (1975)
Buckhout (1974)
Academic Research
– Simulated crime on a TV newscast
– 2,145 callers
– 14.7% were accurate
– Staged assault on professor in front of 141
– 7 weeks later, students shown line-up of six
40% identified attacker
36% identified bystander
23% identified person not there
– 20%
– 31%
Buckhout (1980)
Leippe et al. (1978)
Eyewitness Accuracy
• Cutler & Penrod (1995)
– unusual behavior by customer
– 2 hours later
• 42% made correct ID
• 36% made false ID
• 22% could not ID
• Cromag (1996)
– Boeing 747 crashed into an
11-story building in
– TV footage showed rescue
attempts after the crash
– 66% of students
“remembered” seeing the
plane actually hit the building
What do Witnesses Report?
Fashsing, Ask, & Granhag (2004)
% Reporting
% Accurate
Clothing (upper body)
Clothing (head)
Clothing (pants)
Type of speech
Factors Leading To Wrongful Conviction
(Scheck et al, 2001)
81% of time - Mistaken Identification by eyewitnesses
51% of time - Serology Errors (ABO, protein blood typing)
50% of time - Police Misconduct
45% of time - Prosecutorial Misconduct
35% of time - Forensic Hair Comparison Errors
34% of time - Junk/Sloppy Science admitted at trial
32% of time - Bad Lawyering
22% of time - False Confessions
20% of time - Deliberately False witness testimony
19% of time - Deliberately False snitching by informants
7% of time - Other Forensic Science errors
1% of time - DNA testing errors
Individual Characteristics Influencing Recollection
• Psychological:
IQ, mental retardation, obedience, suggestibility, stress.
• Physiological:
Intoxication, withdrawal, sleep deprivation.
Estimator Variables
Estimator Variables (factors over which the justice system exerts little
or no control):
• Age of witness - children and the elderly tend to be less accurate
than adults
• Level of confidence - this is not strongly correlated with accuracy of
• Facial distinctiveness - faces rated highly attractive or highly
unattractive are recognized better than other faces
• Suspect disguise or changed appearance - this leads to less
accuracy in identification
• Target salience - it is harder to identify a perpetrator if many people
were present at the crime scene
EV (continued)
• Exposure duration - it is harder to identify a perpetrator if the viewing
time is short
• Weapon presence - witnesses tend to focus attention on the weapon
• Crime seriousness - people tend to be less accurate in identification
tests if the the crime is thought to be less serious
• Stress and arousal - moderate arousal tends to lead to better
acquisition of information
• Cross-gender bias - people are more accurate when they identify
someone of their own gender
EV (continued)
Cross-racial bias - people are more accurate when they identify someone of
their own race
Time delay - memory declines over time
Changes in experiential context - it is sometimes difficult to recognize
someone if he or she is seen in a different place
Post-event information - this can distort a person's memory, and can also be
a system variable since this information can come from an interview
System Variables
System Variables (factors that are under the control of the justice
• Lineup instruction - if a witness expects the perpetrator to be present
in the lineup, he or she may feel obligated to pick someone, even if
the perpetrator is not there. The witness should be told that the
culprit is not present is a legitimate answer
• Foil bias - the suspect should not stand out from the innocent
distractors (foils, fillers) in a lineup. The people should wear similar
clothing, etc.
SV (continued)
• Investigator bias - the investigator may unintentionally let
the witness know which person in the lineup is the
• Presentation bias - a sequential presentation of people in
a lineup is better than presenting all people
Police Interrogations & Confessions
• Most damaging evidence that can be presented in court
• Most confessions are negotiated
• Three types of false confessions:
– Voluntary: desire for publicity, guilt, psychopathology
– Coerced-compliant: avoid further interrogation, gain promised
benefit, avoid threatened punishment
– Coerced-internalized: heightened suggestibility
• What percentage of confessions are false? Can’t really know…
Cassell (1996): 10-394 annually in the US
Customized Version
compulsive type-attention seeker -- confesses to gain a piece of the fame, impress
others, or to get attention
compulsive type-homeless -- confesses as a way to get off the streets
compulsive type-fugitive -- confesses to avoid being prosecuted for a crime
elsewhere with stiffer penalties
compulsive type-guilty conscience -- confesses because believes they are guilty
of something
coerced-compliant type -- Kassin's type who pleads guilty to avoid something
aversive in their home environment
coerced-internalized type -- Kassin's type who comes to believe in their guilt out of
interrogation or persuasion
Coerced Internalized Confession
“… Quite often we do not succeed in bringing the patient to recollect what
has been repressed. Instead of that , if the analysis is conducted correctly,
we produce in him an assured conviction of the truth of the construction,
which achieves the same therapeutic results as a recaptured memory….
… the analyst’s inference can reliably fill up the serious gaps in the patient’s
(Freud, S.E. 1937, 23:265-266)
Police Interrogations & Confessions
What can police do :
Misrepresentations of the facts of the case
– Someone has identified the suspect
– Someone has confessed already
– Staged identification procedure
Take unfair advantage of emotions, beliefs or medical conditions
– If the suspect does not confess, the officer will loose his job, his family will
– Feigning friendship, concerns
– Use of informers in jail
– Promising secrecy
Not inform suspect of potential fact or circumstance that may make the
suspect less likely to confess
– Not inform the suspect that an attorney has called
– Not inform the suspect of favorable evidence
Police Interrogations & Confessions
• What police cannot do:
– Courts are reluctant to restrict interrogation tactics
• Physical and psychological coercion
Physical force and torture
Threats of harm or punishment
Isolation and deprivation (food and sleep)
Promises of leniency
Most other techniques are left to the Court to evaluate on a case-bycase basis
Interrogation Method
• Most pressures are experienced by homicide unit (Drizin
& Leo, 2004)
• The Reid Nine Steps of Interrogation
 See MSWord supplementary material [Method of Interrogation Reid)]