Cautionary tale: a systematic review of understanding the police caution for adults in the criminal justice system, and an examination of increasing listenability of the caution

Abstract

Rationale: Research has repeatedly demonstrated that people have difficulty understanding their interrogation rights, as presented in an orally presented police caution. There has been a limited amount of research into possible means of improving understanding, with the application of linguistic, listenability, techniques to caution wording proving most effective amongst students. Methods: This thesis systematically reviewed research exploring verbal caution comprehension amongst adults involved in the criminal justice system, to isolate possible predictors of performance. It then assessed understanding of the Scottish police caution amongst people with an intellectual disability and if this can be improved using a modified (listenability) version. Results: IQ and verbal comprehension appear to have a positive association with understanding. However, the reviewed literature tends to use broad inclusion criteria that may increase confounding variables and reduce opportunity to isolate further possible predictors. People with intellectual disabilities performed poorly in assessment of their understanding of the Scottish police caution, even when the modified version was used. This was despite every participant claiming they had understood. Conclusions: The thesis questions whether the use of a verbal police caution fulfils the intention of communicating interrogation rights as required by law. It suggests more research into caution comprehension is required, with more specific inclusion criteria, to help better understand variables that predict understanding. The relationship between verbal ability and IQ suggest efforts to improve comprehension should be directed to people who have challenges in these abilities, such as people with intellectual disabilities. This should ensure any improvements can benefit a greater number of people. The thesis’ empirical study suggests the method found effective amongst students does not extend to people with intellectual disabilities.