OCR psychology - Interviewing suspects

  • Created by: Ella
  • Created on: 09-10-13 13:04

Interviewing suspects

Mann's study - Detecting Lies

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

Methodology - Field experiment


  • 99 Police officers from Kent
  • 24 female, 75 male
  • Mean age - 34.3 yrs
  • 78 detectives, 8 Trainers, 4 traffic officers, 9 uniformed response officers


Pps/ police officers were shown 54 video clips showing 14 suspects from head to torso so that movement and expression were visible --> clips were baced up by evidence (so it was known if suspects were lying or not) and lasted between 6-145 seconds.

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Interviewing suspects

Mann's study - Detecting Lies

Procedure (continued...)

  • Police officers first filled out a questionnare about their experience detecting lies/liars.
  • They then watched the clips - after each clip they had to indicate whether they thought the suspect was lying or telling the truth, & then rate how confident they were about their decision.
  • Pps were also ased to write down any cues they'd used to detect the liars.


  • Mean lie accuracy - 66.2%
  • Mean truth accuracy -63.6%

This was not significantly different but both significantly greater than chance.

  • Experience in interviewing did correlate with truth accuracy.
  • Most frequently used cues - gaze/eye contact and movements
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Interviewing suspects

Mann's study - Detecting Lies

Evaluation points:

Reliability: A standardised procedure was used - so more easily replicated (high reliability mean more 'sound' conclusions can be made).

Validity: High ecological validity - interviews with suspects took place in real police interview settings. Police would normally record and watch back interviews. High mundane realism.

Ethnocentric: All Pps/police officers weer from Kent - cannot generalise results to other areas/countries/police stations

Participant variables: Some police officers may be better at detecting lies than others or developing rapport with suspects.

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Interviewing suspects

Inbau - Interrogation techniques

Inbau believes that it is justifiable for the police to lie, decieve or use tricks during a interview/interrogation with suspects in order to force a confession.

Inbau's '9 steps' to interrogation:

  • Direct confrontation
  • Give chance to shift blame
  • Never allow suspect to deny guilt
  • Ignore excuses
  • Reinforce sincerity to ensure suspect is receptive
  • If suspect cries, infer guilt
  • Pose an 'alternate question' - one more socially acceptable but both infers guilt.
  • Try to get suspect to admit guilt in front of witnesses
  • Document suspects admission.

Remember - interrogations are designed to increase arousal and anxiety in order for suspects to give a confession.

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Interviewing suspects

Inbau - Interrogation techniques

Evaluation points:


Yes - Inbau outlines 9 steps which can be followed/replicated/used as standardised procedure.

No - Inbau's 9 steps would most likely be carried out differently by different police officers/police stations in different areas/countries, therefore steps cannot be replicated to see if results/interrogation of suspects is consistant.

Validity: Lacks external validity, ie. is ethnocentric as these steps are only used in USA.

Ethics: Possible 'psychological harm' - suspects are interviewed for long periods of time, bombarded with questions, told directly they're thought to be guilty, and any attemps to explain innocence is ignored --> this may then lead to a false confession. 

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Interviewing suspects

Gudjohnsson's study - False confessions

Aim: To document the case of 17yr old 'FC's' false confession, who at the time was distressed and susceptible to interrogative pressures.

Methodology - Case study

Subject/ Pp: 17 yr old 'FC, who was accused of two murders. He was of averae intelligence, suffered from no mental illness and his personality was not obviously abnormal.


  • In 1987, two elderly women were found battered to death in their home.
  • The women's savings were missing and there was evidence of sexual assult.
  • FC was arrested a few days later because of some inconsistancies in his account of his movements during an earlier routine enquiry and e was spending more money than usual.
  • There was no forensic eveidence to link him to the crime.
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Interviewing suspects

Gudjohnsson's study - False Confessions (continued...)

The police interviews:

  • After his arrest, FC was denied access to a solicitor
  • His first interview lasted nearly 14hrs with breaks
  • To start with FC denied being at the scene, but after being repeatedly accused of lying he agreed.
  • Many leading questions were used that were accusatory and many suggested that he was sexually impotent, which he found distressing. Eventually he confessed.
  • The next day he retracted his statement in front of a duty solicitor. There were 3 further interviews.

After a year in jail, he was released by a court after another person pleaded guilty to the crimes - This was a case of 'coerced compliant' false confession.

Psychiatric examination: In prison he was examined by psychiatrists and no evidence of mental illness was found. However, he did score a 10 on Gudjohnsson's Suggestibility Scale making him abnormal in that respect.

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