How good are inpatients at feigning Miranda abilities?: An investigation of the Miranda Quiz, Inventory of Legal Knowledge, and Structured Inventory of Malingered Symptomatology

Abstract

The current study represents the first investigation into feigned Miranda abilities using an inpatient population. We investigated the use of a very generic measure (i.e., the Structured Inventory of Malingered Symptomatology, or SIMS) as well as two specialized forensic feigning measures: the Miranda Quiz (MQ) and Inventory of Legal Knowledge (ILK). With a quasi‐random assignment, 82 acute inpatients were evenly distributed to “feigning” and “genuine” groups. The recommended SIMS cut score > 14 performed poorly, misclassifying three‐quarters of the genuine group as feigning. In general, sensitivities on the specialized scales were constrained by the general lack of severe decrements for the feigning group. However, specificities were strong to outstanding. In particular, the MQ floor effect showed some promise but was limited by its small number of items. The strongest potential was observed for the revised ILK scales, especially the Revised Clinical ILK (RC‐ILK). When using single‐point cut scores on two prior correctional samples, the RC‐ILK produced excellent sensitivities (0.94 and 0.96) and outstanding specificities (0.98 and 0.99). Methodological issues and professional implications were discussed in the context of feigned Miranda abilities.

Forensic assessment instruments: Their reliability and applicability to criminal forensic issues

“…This same team developed empirically based strategies based on items that were "too easy to miss." Importantly, the SAMA feigning scales were able to distinguish between feigners of Miranda deficits and a clinical comparison sample of acute psychiatric inpatients (Rogers et al, 2021).…”

“…Beyond representative data, more recent studies have focused on feigned Miranda incapacities; the SAMA, like other forensic measures, can be feigned (Rogers, Robinson et al., 2017). This same team (Rogers, Henry et al., 2017) developed empirically based strategies based on items that were “too easy to miss.” Importantly, the SAMA feigning scales were able to distinguish between feigners of Miranda deficits and a clinical comparison sample of acute psychiatric inpatients (Rogers et al., 2021).…”