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.

Elemental, configural, and occasion setting mechanisms in biconditional and patterning discriminations.

Three experiments explored the utility of considering mechanisms of occasion setting for understanding patterning and biconditional discriminations - two more complex conditional discriminations in which the stimulus-outcome relations of occasion setting are embedded. In Experiment 1, rats were trained in an appetitive conditioning task with either a biconditional or a patterning discrimination using relatively brief CSs (10s) and differential outcomes as USs. In this study, rats learned the positive patterning task before they had learned negative patterning, and the biconditional task was the most difficult. However, a detailed examination of the results suggested that rats trained in the biconditional task responded to the stimulus compounds mainly on the basis of individual stimulus-outcome associations. Different conditioned response (CR) topographies as a function of reinforcer type complicated interpretation of these results. Experiment 2 confirmed that the biconditional task, with the parameters used here, was not learned, regardless of whether training involved differential or non-differential outcomes. In Experiment 3 the CS duration was increased to 30s and two different USs were used that each supported similar CR topographies. Under these conditions, we observed that whereas the positive patterning task was learned most rapidly, the biconditional discrimination was learned faster than the negative patterning task. Considered in relation to other findings on patterning and biconditional discriminations, the results suggest that elemental, configural, and/or modulatory occasion setting mechanisms may play different roles in these complex conditional discrimination tasks especially as a function of stimulus duration and differential outcome training.

When patterning discriminations are harder than biconditional ones: A cue constellation approach.

Recent attempts to distinguish configural from nonconfigural accounts of causal learning have compared the relative ease of learning 2 kinds of complex discriminations, a biconditional discrimination (e.g., AB+, CD+, AC0, and BD0), and a negative patterning discrimination, (e.g., A+, B+, and AB0), but have yielded conflicting results. Some studies have found the biconditional task to be easier than negative patterning and others have found negative patterning to be easier than the biconditional. This article evaluates these complex discriminations in several studies using a method that attempts to correct methodological problems that arise in comparisons of individual stimuli and stimulus compounds. Across several variations in procedure, negative patterning discriminations were significantly more difficult than biconditional discriminations. The research also found evidence in comparisons across studies that the difficulty of the biconditional, relative to a comparable nonconfigural compound discrimination, depended on whether the task emphasized configural or nonconfigural cues. The overall pattern of results appeared to be well accounted for by models that include configural information, suggesting that theories which invoke configural elements as a basis for learning complex discriminations remain viable explanatory frameworks.