Interviewing suspects

Detecting lies - Mann

Interrogation techniques - Inbau

Falso confessions - Gudjohnsson

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  • Created by: Amy Leech
  • Created on: 21-03-13 10:44

Mann; Police officers' ability to detect lies

Background: Much research has been conduicted on police officers' ability to detect deception whilst interviewing. a review by Vrij of studies conducted after 1980 identified accuracy rates of only 54% (50% achieved by chance). Vrij and Mann's study on 52 Netherlands police officers resulted in 94% (49/52) doing no better than chance (i.e. 50% accuracy) in detecting deception.

Aim: To investigate police officers ability to distinguish truth and lies (during suspect interviews).

Sample: 99 participants working in Kent, UK (75 males, 24 females); mean age of 34 (78 detectives, 8 trainers, 4 traffic officers, 9 uniformed reponse officers.)

Method: Field experiment (using a questionnaire and correlation). Participants first completed a questionnaire about their experience in detecting deception, then watched video clips (head and torso) of 14 suspects in real-life police interviews. 54 clips were used (ranging 6-145 seconds in length). Participants had to judge whether suspect was telling the truth or lying. then complete a scale on how confident they were about their judgements, then list what clues they had used which indicated suspect was lying.

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Mann; Police officers' ability to detect lies

Results: Participants were 66% accurate in detecting lies and 64% accurate in detecting truth both significantly greater than chance level of 50%. Correlations investigating relationship between experience in interviewing and accuracy in detecting a) truth and b) lies resulted in very weak positive correlations (0.20 and 0.18, at 5% level). Cues used (and listed) by participants to detect lying were: gaze, movements, vagueness, contradictions (in accounts) and fidgeting.

Evaluation: Levels of accuracy are higher than those found in previous studies. Interestingly police officers who were good at detecting lies rely more on story cues (e.g. contradictions) than commonly held belief that liars give themselves away by non-verbal cues (e.g. fidgeting or covering mouth with hand). A serious limitation is the lack of control group (to etablish ordinary people's ability to detect deception), although ethical issues arise. Ethics: lay people cannot be exposed to sensitive material unless using actors/made up material (which results in lack of ecological validity and generalisability). Suggestion that experience/ training (nurture) can improve police officers' ability to detect deception which means this research is useful.

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Inbau; Reid's 'nine-steps' interrogation technique

The author is co-writer (with Reid) on a book entitled Criminal Interrogation and Confessions. Although a summary of the principles outlines a technique that clearly assumes the interviewee is guilty, Inbau are opposed to the use of any interrogation technique that might result in the confession of an innocent person. An interview is considered the first appropriate course of action, which the authors recommend should be exploratory and non-accusatory. A clear distinction is made between interviewing and interrogating; where the former is considered to be an exploration and a fact-finding procedure, and the latter is recommended to take part later in the investigative process, when there is good reason to suspect guilt and the primary goal is to gather more information/evidence about the crime committed and secure a confession. These are summarised steps recommend:

1- Confront the suspect with their supposed guilt concerning the offence. 2- Offer the suspect the opportunity to shift the blame (onto another, or explaining, e.g. force of circumstances). 3- Prevent/interupt the suspect if they attempt to deny guilt. 4- Ignore denial. i.e. the suspect's explanations of how/why they couldn't have committed the crime. 5- Maintain good eye contact, use suspects first name, 'understand'/acknowledge suspects difficulties. 6- When suspects becomes quiet, offer alternatives. 7- Offer two alternative explanations of guilt. 8- Ensure witnesses present when suspect admits guilt. 9- Ensure confession is written down and signed.

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Inbau; Reid's 'nine-steps' interrogation technique

Evaluation: This technique may result in false-confessions when used with those who are vulnerable, young, highly suggestible and/or have some mental health issues. Labelling someone as possibly guilty means subsequent behaviour may be interpreted in the light of that label. AS Rosenhan study. e.g denial of guilt is considered (psychodynamic perspective) as a (Freudian) defence of avoidence/denial of the truth; false confessions. Social determinism/situational explanation of behaviour (i.e. admitting guilt/confessing).

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Gudjohnnson; A case of false confession

Background: The dangers of false confessions from suspects who are vulnerable, with mental health issues/learning difficulties or illiterate have previously been acknowledged. There is, however, a general assumption that an innocent person (without any of these difficulties) will not falsely confess. 

Aim: To document a case of false confession.

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

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Gudjohnnson; A case of false confession

Results: Coerced compliant type of confession (suspect confesses to escape/ stop intolerable pressure of interrogation). Psychiatric examination: considered to be without mental illness.Psychometric tests:1)IQ 94, 2) EPI stable/extrovert, 3) suggestibility scale: scored abnormally high (10).

Evaluation: Confrontational interrogations are more likely to lead to false confessions and the possiblity of the real perpetrator not being found (and being at large to commit further crimes); public not protected; waste of time and resources. Social determinism/situational explanations of behaviour. Identifying that people other than those previously considered vulnerable to false confession is essential in order to ensure interview techniques produce valid confessions and to prevent miscarriages of justice.

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