Development and Initial Validation of the Perceptual Assessment of Memory (PASSOM): A Simulator Study.

OBJECTIVE: Performance validity tests (PVTs) are an integral component of neuropsychological assessment. There is a need for the development of more PVTs, especially those employing covert determinations. The aim of the present study was to provide initial validation of a new computerized PVT, the Perceptual Assessment of Memory (PASSOM). METHOD: Participants were 58 undergraduate students randomly assigned to a simulator (SIM) or control (CON) group. All participants were provided written instructions for their role prior to testing and were administered the PASSOM as part of a brief battery of neurocognitive tests. Indices of interest included response accuracy for Trials 1 and 2, and total errors across Trials, as well as response time (RT) for Trials 1 and 2, and total RT for both Trials. RESULTS: The SIM group produced significantly more errors than the CON group for Trials 1 and 2, and committed more total errors across trials. Significantly longer response latencies were found for the SIM group compared to the CON group for all RT indices examined. Linear regression modeling indicated excellent group classification for all indices studied, with areas under the curve ranging from 0.92 to 0.95. Sensitivity and specificity rates were good for several cut scores across all of the accuracy and RT indices, and sensitivity improved greatly by combining RT cut scores with the more traditional accuracy cut scores. CONCLUSION: Findings demonstrate the ability of the PASSOM to distinguish individuals instructed to feign cognitive impairment from those told to perform to the best of their ability.

Still the same in human causal reasoning: Evidence for a uniform similarity parameter in generalisation and summation.

Wagner's replaced elements model (REM) theory implies that generalisation and summation tests depend on a common similarity parameter, but few studies have assessed generalisation and summation within the same experimental paradigm. Three experiments adapted a methodology used in non-human animal studies to investigate this question in the case of human causal reasoning. The studies combined different amounts of training on simple discriminations (A+ vs. C-), compound discriminations (AB+ vs. CD-), and irrelevant novel cue discriminations (An+ vs. Cn-) with testing on single cues, compound cues, and compounds of cues with novel cues. The results were compared with predictions of Pearce's configural model and Wagner's REM elemental model. They also were examined to determine whether generalisation and summation could be accounted for using a single value for the similarity between stimulus compounds and the separable constituent cues of which the compounds were composed. The findings indicated that each theory needed to include common cues to account for the data.