Interrogative Suggestibility among Witnesses with Mild Intellectual Disabilities: the Use of an Adaptation of the GSS

Abstract

Background As part of the assessment of witnesses' ability to provide an account to the police and the courts, information is sometimes sought concerning their level of interrogative suggestibility. The most widely used measure for this is the Gudjonsson Suggestibility Scale (GSS, Gudjonsson 1997), which has two parallel forms (GSS 1 and GSS 2). However, the GSS relates to a verbally presented narrative, not to a visual event, as is more common to witness situations.Methods The present study adapted the scale's format so that the questions referred to a video‐taped incident that had been viewed 24 h earlier by men and women with mild intellectual disabilities (n = 47) and their ‘general population’ counterparts (n = 38).Results The pattern of results was identical to that typically obtained using the GSS in that: (1) compared with their general population counterparts, the participants with intellectual disabilities were more suggestible because of their vulnerability to the ‘misleading questions’; (2) suggestibility scores correlated with the participants' verbal recall of the incident, and (3) both participants with intellectual disabilities and their general population counterparts who were misled by questions in the form of two false alternatives were more likely to select the latter option.Conclusions The implications of these findings for psychological assessments of potential witnesses are discussed.