Measurement of suggestibility in adults with intellectual disabilities: an adaptation of the Gudjonsson suggestibility scales and a systematic review exploring the influence of cognitive variables
Shackleton, Hannah Lydia
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Background: The tendency for accepting and/or behaving under the influence of other’s suggestion in an interview context can be described as ‘interrogative suggestibility’ (IS). The Gudjonsson Suggestibility Scales (GSS) are used within many clinical and forensic settings as a tool to gauge the reliability of information obtained during interviews. Concerns exist regarding the suitability of these scales for use amongst the population of people with an intellectual disability (ID). Previous research concludes that the GSS may disadvantage people with an ID, indicating a greater degree of IS than is actually the case. Method: The following systematic review of several electronic databases explores research to date (and what conclusions have been drawn) in relation to the degree to which cognitive variables relate to scores obtained on the GSS by people with an ID. The subsequent empirical study makes adaptations (e.g. supplementing verbal information with visuals) to the GSS in an attempt to improve its suitability for use with people with an ID. In addition, a number of cognitive variables are measured (e.g. verbal and visual memory) and their relationship with scores on the scales explored. Results: The adaptations to the GSS did not result in a significant change to scores on the GSS. It was found that visual memory ability may contribute to whether visual information effects scores on the GSS following adaptations. Whilst tentative conclusions are drawn regarding the role of memory ability, the systematic review of research was limited in it’s clarification of the role of cognitive variables in IS. This is likely due to limited scope and quality of existing research. Conclusion: Both the empirical study and the systematic review highlight the complexity of the field of interrogative suggestibility, particularly amongst people with an ID.