Core Studies - Making a Case

Aim: To investigate the relative recognisability of internal and external features of a facial composite.

EXPERIMENT 1

Sample: 30 staff and students from Sterling University paid £2 to sort the composites.

Procedure: Photos of 10 celebrities and 40 composites produced by E-SIT, PRO-fit, Sketch and EvoFIT. All were clean shaven with no glasses. 3 sets of composites were used; a 'complete' set, a set with internal features and a set with external features. P's were tested individually on each where they were asked to match the composite with the celebrity face.

Findings: Whole composites and external features were sorted correctly at around 35%. | Internal composites were only 19% correct.

Conclusions: There is something about the internal features of a face that does not work when trying to create a reconstruction, even when the face is familiar as all p's identified faces better with external features.

Criticisms: Reductionist, reliablity 

Aim: To investigate the relative recognisability of internal and external features of a facial composite.

EXPERIMENT 2

Sample: 48 male and female, undergraduate volunteers from Sterling University.

Procedure: A photo-array was used with foils to make it more difficult. The composites were presented one at a time on the photo-array and the p had to pick out the celebrity that matched the composite. They were made easy and hard to identify. The composites were either internal or external.

Findings: External features were identified 42% correct. | Internal features were identified 24% correct.

Conclusions: There is something about the internal features of a face that does not work when trying to create a reconstruction, even when the face is familiar as all p's identified faces better with external features.

Criticisms: Reductionist, reliablity

Aim: To investigate the relative recognisability of internal and external features of a facial composite.

EXPERIMENT 3

Sample: 8 staff paid £10 to be participant witnesses, 54 volunteers asked to do a sorting task and 16 volunteers asked to do a naming task.

Procedure: Familiar or unfamiliar target faces were presented to 'witnesses' for 30 seconds who then created PRO-fit composites. The images were photo shopped to create internal and external only composites which were presented to the sorters and namers.

Findings: Sorting was accurate 57% and didn't matter if the face was familiar or unfamiliar.| External featured 53.3% accurate and internal features 32.6% accurate.| Naming task was 22% accuarte whether familiar or not.

Conclusions: There is something about the internal features of a face that does not work when trying to create a reconstruction, even when the face is familiar as all p's identified faces better with external features.

Criticisms: Reductionist, reliablity

Aim: To provide support for the 'weapon focus' effect when witnessing a crime. 

Sample: 36 students aged 18-31 were paid $3.50.

Procedure: 2 sets of 35mm slides were shown and the 18 slides in each sequence showed people queuing in a fast-food restaurant. In the control group, person B (second in line) was holding a cheque. In the experimental group, person B was holding a gun. All the other slides were identical and shown for 1.5 seconds. The DV was measured by a 20-item multiple-choice questionnaire and the p's were also given 12 head-and-shoulder images and were asked to rate their confidence of identifiction on a scale of 1-6.

Findings: Answers on questionnaire showed no significant difference between conditions.| Performance on the photo line-up was 8.5%.| In control group, 38.9% chose the right person compared to 11.1% in experimental.| Eye fixation was 3.72 on gun compared to 2.44.

Conclusions: P's spent longer loking at the weapon and therefore had difficulty when identifying the criminal, which can be applied to witnesses in real life.

Criticisms: Reliability, Ecological validity.

Aim: To test the cognitive interview in the field.

Sample: 16 experienced detectives from Florida with at least 5 years in the division. 

Procedure: Field experiment with actual interviews of real witnesses. In the first phase, detectives were asked to record a selection of the interviews using standard techniques. This took 4 motnhs and 88 interviews were recorded. P's were then divided into 2 groups, where 1 of them was trained to use CI techniques. This took place over 4 60 minute sessions and 7 detectives were used. Over the next 7 months, more interviews were recorded and were analysed by a team of people from the Uni of California who were blind to the interviews.

Conclusions: Strong support was found for CI because more information was obtained from the witnesses.

Criticisms: Usefulness, Ungeneralisable sample.

Aim: To investigate both threat and unusualness as reasons for witness focus. 

Procedure: P's watched a 2 minute clip consisting of a scene from a hair salon. A man walks to the receptionist and she hands him money. Conditions depended on what the man held in his hand; either a gun, raw chicken, a wallet or nothing. P's did a 10 minute filler activity after which they completed a questionnaire. Witnesses were, for example, asked to describe the man's facial features and clothing and to identify the object he was holding. 

Findings: P's focused the longest on the raw chicken. (high unusualness, low threat).| Accuracy of p's descriptions was due to unsualness, not threat.| P's had trouble identifying low unusualness, low threat object (wallet).| "weapon focus" was only evident in p's descriptions.

Conlcusions: The effects of objects being held by the perpetrators draws the witnesses' attention away from the perpetrator is not an effect unique to weapons - any unusual object would have the same effect. This suggests that when weapon effect occurs, it could be due to weapon unusualness, not threat.

Criticisms: Opposing evidence, lacks ecological validity. 

Aim: To replicate the first experiment using a different scenario.

Procedure: The same as experiment 1 but the video was in a repair shop in which the male target approaches the receptionist, speaks to her, receives some money and drives away. The objects the man was carrying were; a butcher knife, a screwdriver, sunglasses and a Pilsbury Dough Boy.

Findings: Unusualness, not threat, seemed to have attracted and held more attention to the p's.| The unusualness also affected the p's descriptions of the man.| Witnesses again had troiuble remembering the low unusualness, low threat object (sunglasses).

Conlcusions: The effects of objects being held by the perpetrators draws the witnesses' attention away from the perpetrator is not an effect unique to weapons - any unusual object would have the same effect. This suggests that when weapon effect occurs, it could be due to weapon unusualness, not threat.

Criticisms: Opposing evidence, lacks ecological validity.

Aim: To test police officers' ability to distinguish truths and lies during police interviews with suspects.

Sample: 99 Kent police officers, 24 female, 75 male. There were 78 detectives, 8 trainers, 4 traffic officers and 9 uniformed response officers.

Procedure: P's asked to judge the truthfulness of people in real-life interviews. They saw 54 videos of 14 suspects showing their head and torso, the expression and movement were visible, they also rated their confidence. Clips were backed up with evidence to do with whether they were lying or telling the truth. P's listed the cues they had used to detect lies.

Findings: Mean lie accuracy was 66.2%.| Mean truth accuracy was 63.6%.| Both higher than chance (50%).| Frequently mentioned cues were gaze, movements, vagueness, contradictions in stories and fidgeting.

Conclusions: The accuracy exceeded findings from other studies, however to find out if they were better than non-professionals, a control group would have to be used.

Criticisms: Good validity, Not representative.

1. Direct confrontation - suspect told directly they are thought to have committed the crime.

2. Suspect is given the chance to shift the blame away from themselves by being offered some justifications for what happened. Interrogator should show sympathy and understanding.

3. Suspect should never be allowed to deny guilt, interrupt them to prevent them getting the psychological advantage.

4. Suspect will try to give reasons why they couldn't have committed the crime, try to move this towards a confession by ignoring them. 

5. Reinforce sincerity by staying close, keeping eye contact and using first names.

6. Suspect will become quieter and listen, move towards offering alternatives and if they cry, infer guilt.

7. Give them 2 choices, one more socially acceptable than the other to give reasons as to why.

8. Get the suspect to admit guilt in front of witnesses.

9. Document their admission and get them to sign a confession. 

Aim: To document a case of the false confession of a youth who was at the time distressed and susceptible to interrogative pressure.

Sample/Procedure: Case-study on a 17 year old boy, named FC, who was accused of 2 murders. In 1987, 2 elderly women were found dead in their home, the women's money was missing and their was evidence of sexual assault. FC was arrested because of some inconsistence in his story and he was spending more money than normal. No forensic evidence linked him to the crime. He was denied a solicior and was interviewed for 14 hours, with breaks. After being repeatedly accused of lying he agreed. Many questions were leading and and suggested he was sexually impotent. After a year in prison he was released when the real criminal confessed.

Findings: Scored 10 on GSS for high suggestability.| No evidence for mental illness was found.| Came out of prison as a stable extrovert.

Conclusions: This is a case of 'coerced compliant confession' meaning he gave a false confession to escape the stressful situation. 

Criticisms: Use of case study, usefulness.

Aim: To test the reliability of organised/disorganised typologies.

Sample: Content analysis of 100 cases of serial killers from the USA.

Procedure: Using the psychometric method of multideminsional scaling, Canter attempted to find out if the features hypothesised to to belong to each typology would be consistently and distinctly different. They were cross-checked with court reports and officers where possible. Collected over several years and called the Missen Corpus. The 3rd crime of each case was studied and The Crime Classification Manual was used to classify the crimes as organised or disorganised.

Findings: Disorganised offenders are more common or more easy to find as twice as many were found as organised.| The body being concealed co-occurred in 70% and sexual activity co-occurred in 75%.| Sex acts were found in more than 2/3 of disorganised.| Organised variables appeared central and disorganised surrounded them.

Conclusions: Crimes have an organised and disorganised element to them, so Canter suggests looking at individual differences would be more appropriate.

Criticisms: Reliability, Validity, Opposing evidence.

Aim: To identify a behaviour pattern from similarities between offences.

Sample: 66 offences from various police forces committed by 27 offenders.

Procedure: Content analysis was done to find 33 offence variables that were clearly linked to a potential behaviour characteristic. They said 'yes' or 'no' to each variable.

Findings: Following variables were found in all 66 cases; vaginal intercourse, no reaction to the victim, impersonal language, surprise attack, victim's clothing disturbed. This suggests a pattern of behaviours where the attack is impersonal, sudden and the victim is irrelevant.

Conclusions: All 5 aspects have been found to contribute towards all sexual offences in current cases which can lead to an understanding of how an offender's behaviour changes over a series of offences and allowing them to understand if offences have been committed by the same person.

Criticisms: Good reliability, usefulness.