Interrogations-and-Confessions-Handbook

CHAPTER 13
Suggestibility: Historical and
Theoretical Aspects
My interest in ‘interrogative suggestibility’ began in 1980 when I took a post as
a Lecturer in Psychology at the Institute of Psychiatry, University of London.
I was commonly being asked by defence and prosecution counsels to prepare
court reports involving the assessment of the reliability of evidence. These referrals
generally related to two types of case:
1. where victims with learning disability were going to be called to give evidence
but there was concern about the likely reliability of their evidence;
2. where defendants had retracted confessions made during police interviewing.
Cases of the former type were generally referred by the prosecution, and the
latter by defence counsel. It soon became apparent that the legal advocates
were particularly interested in the individual’s level of suggestibility.
In a pioneering single case study, Professor John Gunn and I (Gudjonsson &
Gunn, 1982) established a precedent at the Central Criminal Court in London
(also known as the Old Bailey). The case involved a 22-year-old woman with
learning disability, called Mary, who claimed that she had been sexually assaulted
by a group of young men and women. The Director of Public Prosecutions
requested an answer to three main questions.
1. Was Mary competent as a witness in a court of law?
2. If she was competent, was she reliable as a witness?
3. Was she severely subnormal as defined in the Mental Health Act 1959?
Being able to establish the likely reliability of Mary’s statements was particularly
important as her testimony was the main prosecution evidence against
six defendants.
The psychological assessment, carried out by myself, focused on Mary’s learning
disability and the likely reliability of her evidence. The assessment was
carried out during two sessions on the same day. Mary obtained a Full Scale
IQ of 47 on the Wechsler Adult Intelligence Scale (WAIS). At the time of the
assessment there was no standardized psychological test available that could
be used to assess the reliability of Mary’s testimony. For this reason I used