G543 - Making A Case


Recognising Faces

  • Being able to accurately identify a face is key to many convictions.  
  • However, cases of mistaken identity show that this is not always as easy as it seems.
  • Witnesses to crimes ar e often asked to help develop identikits or in the past photofit pictures of the suspect as it is often difficult to describe the face using words.
  • Modern technology allows witnesses to pick specific features from an enormous database and then the image can be digitally altered to make it look more accurate and automatically aged or evolved to accurately reflect the suspect.
  • Facial recognition can be divided into internal and external features.
  • Internal features are eyes, brows, nose and mouth while external features are head shape, hair and ears.
  • External features are more important at identifying unfamiliar faces while internal features help identify familiar faces.
1 of 17

Bruce's Study

Aim:  to investigate peoples ability to recognise faces.  

Method:  lab experiment

Participants:  30 participants from a university

Procedure:  they were shown 10 target photographs of male celebrities with 40 facial composites. They were asked to match the facial composites to the photographs.  One group was given full composites.  The second group was given composites with only internal features and the last group were given only external composites. 

Findings:  33% of external or full composites were accurately matched.  19.5% of internal composites were accurately matched.  

2 of 17

Factors affecting Identification

Factors which affect identification: 

  • anxiety/stress
  • leading questions
  • weapon focus
  • post event discussion

Weapon focus refers to an eyewitnesses concentration on a weapon to the exclusion of other details of a crime.  

It is not unusual for a witness to be able to describe the weapon in much more detail than the person holding it.  

Humans tend to fix their attention on highly dangerous or unusual objects for longer than uncommon objects.

3 of 17

Loftus's Study

Aim:  to provide support for the weapon focus effect which affects witnesses during crimes where a weapon is present:

Method:  Laboratory experiment

Participants:  36 students from the University of Washington.  

Procedure:  two sets of slides showing a restaurant situation.  In the first set the customer pays for his meal with a cheque, whilst in the second the customer draws a gun.  After viewing the slides the participants were required to fill out a questionnaire which included a line up of 12 faces from which they had to identify the customer.  

Findings:  In the condition without the gun 39.7% of participants could correctly identify the customer.  In the condition with the gun only 11.1% of participants accurately identified the customer. 

4 of 17

Cognitive Interview

Forensic psychologists combines various ideas and design and more effective ways of questionning witnesses that avoid any chance of leading the victim.  One of the most widely used aids to recall is the cognitive interview technique.

Cognitive interviews can be useful with witnesses regardless of whether they are the victim or the witness.  Fisher & Geiselman devised a cognitive interview technique arguing that the police inadvertently discouraged the witness from remembering all they can by asking closed questions which do not encourage elaboration or by interrupting the witness using a standard interview technique.

There was a sense of powerlessness of the part of the witness with the police officer in a dominant role and it is this type of relationship that the cognitive interview attempts to break down.  If the witness is put at their ease and allowed to take the dominant role, the witness is more likely to give as much information as they can.  In a CI the witness is encouraged to relate their whole story without interruptions whilst police officers take an active listening role.  Asking open ended questions and avoiding a judgmental role on the part of the police is also encouraged. 

5 of 17

Fisher's Study

Aim:  To investigate the effectivessness of the Cognitive Interview technique in enhancing recall in witnesses and victirms.  

Method:  field experiment

Participants:  16 experienced detectives from the robbery division of the Florida Police Department.

Procedure:  preliminary phase - the detectives take recorded interviews using standard interviewing procedures from the amount of information gathered and recommendations of detectives commanding officer two groups were formed.  One trained in the use of Cognitive Interviewing Techniques (10) the remainder were the untrained controlled group (6).  Training was conducted in four one hour sessions.  Post training phase - seven trained and six controls take recorded two to seven cases each with a total of 47 interviews recorded.  Taped transcriptions and counting number of relevant objective statements was completed by two different groups of research assistants who were blind to the condition of the interviewer.  

Results:  47% more information was found when the detectives were trained in Cognitive Interview,  63% more information from the trained detectives compared to untrained detectives.

6 of 17

Detecting Lies

After arrest the purpose of the interview is to gather further evidence to establish guilt or innocence.  One of the main things that the police have to ascertain is whether the person they are interviewing is lying.  In the British legal system a defendant is presumed innocent until proven guilty.  Police officers like to think they are good at detecting lies and are trained to look for non verbal cues such as looking down, putting their hands over their mouth, inconsistent responses, averting eyes, appearing nervous or laughing or sighing as these are often used an indicator of a person who is using deception.

However, research does not always support these beliefs and in fact it is often contradictory and most evidence shows that people are not very good at spotting lies.  It is suggested that looking at indirect methods of deception is more effective than looking for lies. As such Police Officers should attend not to wehther they thought the suspect was lying but whether the suspect was having to think hard. 

7 of 17

Mann's Study

Aim:  to investigate police officer's ability to distinguish truths and lies.

Method:  field experiment

Participants:  99 police officers working in Kent, 75 males and 24 females.

Procedure:  participants first completed a questionnaire about their experience in detecting deception.  They then watched video clips of 14 suspects in real life police interviews.  The participants had to judge whether the suspect was telling the truth or lying then complete a scale on how confident they were about their judgements and then list what cues they had used which indicated the suspect was lying. 

Results:  the participants were 66% accurate in detecting lies and 64% accurate in detecting truth.  Cues used by participants to detect lying were gaze, movements, vagueness, contradictions and fidgeting.

8 of 17

Interrogation Techniques

The purpose of an interrogation is to extract a confession from a suspect.  The psychology behind an interrogation is to create a situation in which suspects feel that they can admit their guilt.  Whenever they say wsomething they are interrupted or ignored unless it is what the interrogator wants.  When cornered they are offered two alternatives, both admitting guilt but one seemingly more acceptable.

Inbau believes that it is justifiable for the police to lie, deceive or use tricks to force a confession.  This may be acceptable in the USA, but it is not allowed in the UK.  

Argued that a non-accusatory interview must take place before an interrogation so more information can be gathered.

9 of 17

Inbau's Study

There are 9 steps to an effective interrogation (Reid technique):

1.  Confront suspect with supposed guilt.

2.  Offer opportunity to shift blame

3.  Prevent suspect from denying guilt.

4.  Ignore denials.

5.  Maintain eye contact and understand the suspect.

6.  Offer alternatives once suspects is silent.

7.  Offer two alternatives, both admitting guitl.

8.  Ensure witnesses are present.

9. Ensure confession is written and signed. 

10 of 17

False Confessions

There are three key types of false confession:

  • Voluntary confession (purposeful false confession)
  • Coerced confession (the false confessor still knows they didn't do it but confesses anyway)
  • Coerced internalised confession (the false confessor starts to believe that they did it)

Some vulnerable suspects who may have low intelligence, are naive, have low self esteem, lack assertivenes and are highly anxious correlate highly with interrogative suggestibility.

Gudjonsson has devised that the Gudjonsson Suggestability Scale which taps two different aspects of interrogative suggestability, namely the tendency to give into leading questions (yield) and a tendency to shift responses under conditions of inter personal pressure (shift).  Investigators can use the GSS to help evaluate whether the confessions have been coerced or to determine how best to question a suspect. 

11 of 17

Gudjohnsson's Study

Aim:  to document a case of false confession. 

Method:  case study.

Participants:  a 17 year old of average intelligence with no mental health issues. 

Procedure:  Case study compiled from information summarised from several police interviews with the suspect and later psychiatric examination and psychometric tests of the suspect.  The crime they were accused of were murder, sexual assault and robbery of two elderly woman found battered to death in their home and their savings missing.  The suspect was interviewed by the police.  The first interview in the presenc eof the police lasted around 14 hours with some breaks.  It included leading questions. accusations of lying and guilt and suggestions and taunts about his sexual impotence.  The second interview conducted the next day in the presence of the solicitor resulted in a retraction of the previous days statement  Later under pressure and following further accusations about his failure of women he confessed.

Results:  A coerced compliant type of confession where the suspect confesses to escape or stop intolerable pressure of the investigation.  The participants scaled abnormally high on Gudjonssons Suggestability Scale. 

12 of 17

Top Down Approach

  • Used in the US (using ViCap) - used by the FBI
  • Police will put together an idea of what they are looking for and look for things in a crime scene to support their idea. Crimes are classified as either organised or disorganised.
  • Creates typologies of criminal behaviour and motivations from interviews with captured criminals. 
  • They match a type of criminal to the features of a particular crime. 

Four main stages used by the FBI for profiling:

  • Data assimilation (police reports, forensics, autopsies)
  • Crime classification (suicide, homicide, robbery, GBH)
  • Crime Reconstruction (hypothesis of behaviour, modus operandi)
  • Profile Generation (suggestions of demographics, habits and personality)

Organised offenders show evidence of planning, they target the victim and try to control the situation.  They have at least average intelligence and social and sexual competence.

Disorganised offenders tend to be socially inadequate and know the crime scene and the victim.

13 of 17

Hazelwood and Douglas's Study

Published their account of the 'lust murderer' in which they advanced their theory of organised and disorganised crime. Their theory postulates the beginnings of the typological approach to offender profiling. 

Organised Offender:

  • They will lead an orderely life and will kill following a critical event in their life.
  • Their actions will reflect planning and control (ie bringing their own restraints etc with them) and the crime scene will reflect their order and planning
  • More likely to use a verbal approach with victims and be of high or above average intelligence.

Disorganised Offender:

  • Likely to commit a crime in the heat of the moment.
  • There is likely to be no pre-planning or thought using items already found at the scene.
  • They may leave DNA evidence, fingerprints, or the weapon at the scene. 
14 of 17

Bottom Down Approach

  • No theory is constructed beforehand and comes as a result of the features and details of the crime scene.
  • Building up a profile of an offender by finding association with the characteristics of the offence and the type of offender. 
  • It uses statistical analysis and application of psychological principles - geographical profiling, small space analysis and five factor theory.

Inter-personal consistency:

  • Behaviour of the offender at the time of the crime is comparable to what they are like in daily life.
  • A degree of violence used in serious crimes (****) may reflect how the criminal may treat other women in his life.

Spacial Consistency:

  • Marauder's - commit their crimes close to home and are usually disorganised.
  • Commuters - commit their crimes away from home and are usually organised. 
15 of 17

Canter's Study

Aim:  to identify associations between aspects of the offenders characteristics and offence behaviour using scientific objective measures.

Participants:  27 sex offenders (and their 66 sexual offences)

Procedure:  initial exploration of a range of crimes in which full information was available.  33 offence variables were identified through data available (witness statements and police reports), behavioural variables with low frequencies were excluded and variables were categorised with Yes/No values (ie, presence or absence of behaviour). Content analysis and subsequent small space analysis (a multi-dimensional scaling procedure examining relationship between one variable and every other examined which represents correlation between variables as distances in statistically derived geometric space).

Results:  analysis of factors indicates that there are five variables that are central to rate (vaginal intercourse, no reaction to victim, interpersonal language, surprise attack, victirms clothing disturbed) which Canter considers as indicative of a impersonal surprise attack.  Another constellation of variables (attempted intimacy, impersonal interaction) would be predicted to be a reflection of a general approach to women in the offenders everyday life (seeing them as sex objects)

16 of 17

Case Study: John Duffy

Between 1975 and 1986, 23 women were ***** at railway stations in and around London.  In 1985, the serious nature of the crimes escalated into murder.  Canter placed all the places on a map and this allowed him to speculate where the ****** might live.  This was developed into a circle theory and then a further hypothesis where he categorised perpetrators as marauders or commuters.  

Canter identified 17 profile points.  Later it was found that the perpetrator matched 13 of the 17 profile points.  Canter's profile suggested a number of possible offender characteristics which allowed the police to narrow down the list of around 2000 suspects.  Duffy was apprehended and ultimately convicted in 1988 of two murders and five rapes.  

Canters Profile

Profile of likely offender:

  • Lived in Kilburn/Cricklewood area where first three offences occurred - Duffy found to live in Kilburn
  • Needed to dominate women - Duffy was violent and had previously attacked his wife
  • Keeps souvenirs from crimes - Duffy had 33 door keys, each taken from the victim
17 of 17


No comments have yet been made

Similar Psychology resources:

See all Psychology resources »See all Criminological and Forensic Psychology resources »