Psychological Assessment & Expert Witness Assessment

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Suggestibility Assessments | Expert Witness Blog

Suggestibility Assessments

How Does Suggestibility, Conformity, Obedience and Compliance Result in False Confessions or Illegal Behaviour?

"Suggestibility has been shown by psychologists to cause false confessions. Psychologists have demonstrated conformity, obedience and compliance can cause illegal behaviour. An assessment by an expert psychologist of a defendant who is considered to be suggestible or compliant is a crucial part of constructing a defence that ensures there are no miscarriages of justice."

What is a False Confession?

A false confession occurs when a defendant, admits to a crime that they did not commit. The psychological process of false confessions is complex. However, the research reviewed by our expert psychologists and their practical experience of working with defendants and in the criminal justice system demonstrates that some individuals are psychologically more likely to confess to crimes than others. There are often psychological factors which can be objectively measured in some defendants which show a propensity to make false confessions to crimes that they did not commit.

There are several reasons why an individual might make a false confession, for instance, a defendant may make a false confession to attempt to mitigate the possibility of receiving a harsher sentence when, although they are innocent, the factual evidence does not support their innocence. Sometimes, defendants may make a false confession to protect a friend or relative who committed the crime. In other instances, a defendant may confess to something they did not do because they are suffering from a mental disorder. Defendants may make a false confession in response to a bribe from a third party. False confessions also frequently occur when individuals are easily led, have low IQ or personality factors resulting in them feeling pressurised into admitting to offences they have not committed.


How Does Offender Suggestibility Impact on the Quality of Evidence?

"In legal psychology, suggestibility relates to the phenomenon that is found when a subject under interrogation yields to leading questions when pressure is applied and shifts their answers when interrogative pressure is applied. Put another way; the psychologically suggestible suspect admits facts which are incorrect under pressure. This is often called interrogative suggestibility. For lawyers, the concept of suggestibility is vital because it is critical that the court has robust evidence to show the defendant’s guilt or innocence. Suggestible defendants may, therefore, admit offences that they did not commit because of their suggestibility, the quality of their evidence under cross-examination in court is likely to be reduced, and they are unlikely to come up to proof."

Suggestible witnesses often possess one or more of the following characteristics:

  • A low IQ or learning disability;
  • Submissive personality;
  • Conforming personality;
  • Are suffering from a mental illness;
  • Are juveniles; and
  • A low Mental age

The leading measure of suggestibility is a psychological test called the Gudjonsson Suggestibility Scale (GSS). Gudjonsson Suggestibility Scale Download. Elevated scores on the GSS are correlated with suspects who are likely to make false confessions under cross-examination or interrogation.

Advanced Assessments’ expert witness psychologists use the GSS in combination with other psychological tests, such as personality tests, IQ test as well as a structured clinical interview, the Wechsler Memory Scale, the Test of Memory and Learning, observations and content analysis of the relevant documents to objectively assess whether the suspect is suggestible. By using this multi-method approach, our expert psychologists can gather robust and reliable objective data to clearly show whether a subject is, in fact, suggestible. In this way, our expert psychologists can use reliable and valid evaluations of suggestibility that rule out attempts to fake suggestibility and meet the very high standards required under the expert’s overriding duty to the court.

Why is Police Suspect Suggestibility Important in Legal Proceedings?


Our expert psychologists assess police suspect suggestibility to establish whether a defendant is likely to produce false low-quality evidence and false accounts when interrogated by the police or cross-examined in court. The GSS is sometimes used along with other psychological tests to determine whether a defendant is fit to plead and fit to stand trial.

An assessment of suggestibility is also essential when determining whether eyewitness evidence is reliable in criminal, civil, employment tribunal, personal injury and other legal proceedings.

How Does Conformity, Compliance and Obedience Differ from Suggestibility?

Conformity, compliance and obedience are different to the psychological concept of suggestibility. The concept of obedience and conformity can explain why defendant’s commit offences under the orders of individuals who they regard to be authority figures. The psychological phenomenon of obedience was demonstrated by Stanley Milgram of Stanford University. Milgram's research showed that ordinary people would obey authority figures and administer lethal doses of electric shocks, which would apparently kill the person on the receiving end. This work was ultimately used to explain the war crimes committed during the Second World War.


The concept of conformity, on the other hand, is used to explain the psychological process where individuals will change their behaviour and views to fit in with the dominant view of the group, to such an extent that they may give factually wrong information because of group pressure. The leading study was carried out by Solomon Asch, who demonstrated how susceptible individuals are to group pressure.

Find Out More About the Psychology of Suggestibility, Conformity and False Confessions


Conformity, Compliance, and Obedience

False Confessions