Psychologists are commonly called upon to conduct evaluations of a defendant's competency to stand trial. Under Dusky v. United States (1960) the legal criteria for competency to stand trial were enumerated and since then, a number of standardized assessment instruments that aim to assess those criteria have been developed, each with its own noted strengths and weaknesses. Although there are several instruments available to aid clinicians in these types of evaluations, only three include screens for feigning, and only one assesses for feigned cognitive impairment. In the current research an instrument was constructed to assess for competence related knowledge, while also incorporating several logical and statistical methods to assess for a feigned lack of knowledge of the legal system, including forced-choice testing, floor effect strategies, and completion time methodologies. The Factual Understanding Instrument (FUI) was constructed over five studies. Studies 1-3 involved instrument construction and included a review of the literature, a critical incidents phase with experts in the field, and item construction. Studies 4-5 focused on item evaluation and included an expert review of the constructed items and the pilot testing of the FUI in a simulation study with unimpaired college students. In study 5, multiple statistical analyses were conducted to evaluate the FUI items and the various feigning detection strategies. In this sample reliability of the FUI was high. Items were relatively easy for honest responding participants, with many scoring near perfect. Feigning participants did not score as low as would be predicted by symptom validity testing, as responses varied from less than 50% correct to values seen in honest responders. Intelligence level, item difficulty, and response condition were found to be significant predictors in responses to FUI items. Completion time was not supported as a feigning detection method as hypothesized, however, alternative interpretations of the theory are offered. Further research on the FUI with a known-groups sample in forensic settings is needed to establish a floor value, to further evaluate item performance, and to improve the external validity of the current research. Research methodologies and future directions are offered.
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