Recognising Faces - Bruce et al. 1988
Aim To investigate which is more recognisable internal or external features.
Method Three laboratory experiments.
Participants Experiment 1: 30 staff/students from Stirling uni were paid £2 to sort the composites, 15 male 15 female (mean age 29.2). Experiment 2: 48 undergraduates at Stirling uni, 21 males 27 females all volunteers.
Procedure Experiment 1:The participants in this task were asked to match up 40 composite images, made with E-FIT, PRO-fit, Sketch and EvoFIT, to 10 celebrity photos. Three sets were used containing either the whole face, just internal features or just external features. Experiment 2: The participants in this task were shown a photo line up of celebrities then shown the composites one at at time. The participants had to pick the celebrity face that matched the composite they were shown. Again only internal or external features were used.
Bruce et al. 1988
Results Experiment 1: People matched external features and whole faces correctly 35% of the time and only 19.5% of the time with internal features.
Experiment 2: Images of external features (42%) were identified more easily than internal features (24%) and this was consistent across difficult and easy types.
Conclusions Participants performed just above chance with internal features and did better with external features and whole faces suggesting that even with recognisable faces like celebrities it is hard to reconstruct the internal features.
It would seem that facial reconstruction is based on two variables:
Stimulus variable - how much meaning to the individual has the face to be remembered?
Subject variable - how much individual variation is there in the ability to remember faces?
Factors influencing identification - Loftus et al.
Aim: To provide support for the 'weapon focus' effect when witnessing a crime.
Method: A lab experiment
Participants: 36 students at the University of Washington, aged 18-31. Recruited through advertisment and either given $3.50 or extra credit in psychology class.
Procedure: Control: Participants were shown slides of a queue of people in a Taco Bell restaurant. Person B hands the cashier a cheque. Experimental: Participants were shown the same slides as the control but person B pulls a gun instead. Participants were asked to fill out a multichoice, 20 item, questionnaire and to pick person B out 12 head to shoulder photos and rate how confident they were in their choice on a scale of 1-6.
Results: Questionnaire results showed no difference across conditions. In the control participants chose correctly 38.9% of the time whereas those in the weapon condition on chose correctly 11.1% of the time. There was no difference in confidence of the participants across the conditions and eye fixation data showed an average of 3.72 on the gun and 2.44 on the cheque.
Conclusion:Participants spent longer looking at the weapon therefore had more difficulty identifiying the suspect from the photo line. A second experiment with 80 students supported this. The influence mey be further enhanced in a real world situation when a witness would be more aroused.
The Cognitive interview - Fisher et al. 1989
Aim To test the cognitive interview (CI) in the field.
Method Field experiment with actual interviews of real witnesses by serving police detectives.
Participants16 detectives with minimum 5 years in the robbery division of Dade county.
ProcedurePhase 1: Detectives were asked to record their interviews using their regular techniques. 88 interviews were collected. Phase 2: Detectives were divided into 2 groups, one was trained in CI techniques during 4 1 hour sessions. 7 detectives completed the training and were used in the results. More interviews recorded then analysed by a team at California University who were blind to the conditions.
Results The CI trained detectives collected 47% more info than before and 63% percent more than the untrained detectives. No difference in accuracy across conditions and CI took longer.
Conclusion Strong support was gathered for CI as more information was collected with no loss of accuracy and only a little time increase.
Detecting Lies - Mann et al. 2004
Aim: To test police officers ability to detect lies when interviewing suspects.
Method: Field experiment.
Participants: 99 Kent police officers, 24 females, 75 males, mean age 34.3. Among them were 78 detectives, 8 trainers, 4 traffic officers and 9 uniformed response officers.
Procedure: Participants were asked to judge the truthfulness of people in real life police interviews. The participants were shown 54 clips of 14 suspects and had to fill in a questionnaire about their experience in detecting lies. After each clip they had to indicate whether they thought the suspect was lying or not, how confident they were in their answer and what cues they used to detect the lie.
Results: There wasn't a significant difference between lie and truth accuracy but both were significantly above chance. Also the more experience an officer had the greater the lie and truth accuracy. The most frequently mentioned cues were gaze, movements, vagueness, contradictions in stories and fidgeting.
Conclusion:The levels of accuracy in this study would have been highly supported in a control group of lay people was used but lay people cannot be shown sensitive material. The more experience an officer has the better they are at detecting lies. Good lie detectors rely more on story cues than body language.
Interrogation Techniques - Inbau et al. 1986
Nine steps of interrogation:
1. Direct confrontation - the suspect is told they are thought to be the offender
2. The suspect is given the opportunity to shift the blame from themselves. Interrogator should show sympathy to make admitance of guilt easier.
3. Suspect should never be allowed to deny guilt interrupt any denials of guilt.
4. Ignore any reasons as to why they ciould not have commited the crime.
5. Reinforce sincerity by keeping close, keeping good eye contact and using first names.
6. When the suspect eventually becomes quiter move towards alternatives, if they cry infer guilt.
7. Pose the 'alternative question' both choices admit guilt but one is more socially acceptable than the other.
8. Get the suspect to admit guilt in front of witnesses.
9. Document their confession and get them to sign it to avoid them retracting it later.
Inbau thought the use of this technique was justified because it was used on people who were deemed suspects through their preliminary interview but it has been found that using this technique on young or mentally impaired people can lead to false confessions.
False Confessions - Gudjohnsson et al.1990
Aim: To document the false confession of a youth who was under pressure and distress.
Method: Case study
Subject: A 17 year old youth (FC) accused of two murders. He was of average intelligence and wasn't obviously abnormal in any way.
Background: In 1987 two elderly women were found having been sexually assaulted then beaten to death. They had also been robbed of their savings. A few days later FC was arrested due to some inconsistencies is his account of where he was that night and the fact he'd been spending more than usual. There was no forensic evidence to link him to the offense. He was denied a solicitor and later confessed after a lengthy interview with the police. The next day in repeated his confession in front of a solicitor then wrote a statement condemning himself to jail. After a year another person pleaded guilty to the crimes and FC was released.
The police interviews: FC's first interview lasted for nearly 14 hours with breaks and he was questioned by officers. After many leading questions and suggestions that he was sexually impotent and bad with women he confessed. He retracted his statement the next only to confess again under the same pressure. There were 3 further interviews.
Psychiatric examination: He showed no sign of mental illness had an IQ of 94 but was highly suggestible and he came out of a personality test and a stable extrovert.
Gudjohnsson et al. 1990 continued...
Conclusion: This is a case of 'coerced compliant' false confession, meaning that he gave in to pressure in order to escape from a distressing situation. It shows this can happen to anyone and not just the mentally impaired or those with lower IQs. Following his release FC changed in personality and his self confidence improved.
Top-down Typology - Canter et al. 2004
Aim: To test the reliability of organised/disorganised typologies.
Method: A content analysis using the psychometric method of multi-dimensional scaling was applied to 11 cases to find out if the features thought to belong to each typology would be consistently and distinctively different. The cases came from published accounts of serial killers collected an independent researcher. The third crime in each case was analysed and the crime classification manual was used to determine whether the crime was organised or disorganised.
- Twice as many disorganised as organised crime scene actions were identified.
- Two behaviours occurred in the organised crime significantly above chance, sexual activity (75%) and hiding the body (70%).
- Only sex acts occured in more than two thirds of disorganised cases.
- Organised variables appeared central in the scattered plot, with disorganised variables spread widely around them.
Conclusion: Canter concludes that rather than there being two distinct types of serial killer all the cases were going to have an element of organisation as none of the killers analysed were caught after 3 killings. A better way would be to look at the individual differences of the offenders.
Bottom up approaches - Canter and Heritage 1990
Aim: To identify a behaviour pattern from similarities between offences.
Method: A content analysis of 66 sexual offences from various police forces committed by 27 offenders was conducted to find 33 offence variables that were clearly linked to a potential behaviour characteristic.
Analysis: The data was subjected to a smallest-space analysis.
Results: Central behaviours included, vaginal intercourse, no reaction with the victim, impersonal language, surprise attack and victims clothes were disturbed. Less central behaviours included, attempted intimacy with the victim, sexual behaviour, overt violence and aggression, impersonal interaction and criminal behaviour and intent.
Conclusion: These 5 factors have been shown to contribute to all sexual offences but in different patterns for different individuals which can lead to understanding how an offenders behaviour changes over time or whether two or more offences were committed by the same person. This has become known as the 5-factor theory.
Case Study - Canter, The case of John Duffy 1980
John Duffy was a serial ****** and killer who, in 2000, confessed to comitting 25 offences between 1975 and 1986. His victims were always women, aged between 15 and 32 and targeted near railway stations in and around london. Canter got involved in the early 80's and based his profile on the locations of the crimes and the evidence of Duffy's behaviour. According to his profile Duffy was a marauder who commited his crimes near his home.
Preliminary profile: Canter suggested that the suspect would:
Have possibly been arrested some time after 1983.
Have lived in the area circumscribed by the first three cases since 1983.
Probably lived in that area at the time of arrest.
Probably lives with a woman but no children.
Mid to late twenties, light hair, 5 foot 9, right handed.
Probably semi skilled with a job involving weekend work or casual labour from july 1984.
His job probably doesn't bring him into contact with public.
Probably has one or two very close male friends little to no contact with women.
Knowledge of the railway where the attacks happened.
Considerable sexual experience due to the variety of his sexual actions.
Probably arrested between 82 and 84 due agression cause by drink or drugs.
Duffy was caught out of 2000 suspects using this method.