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We found countermeasures to protocols using P300 in concealed information tests. One, the "six-probe" protocol, in Experiment 1, uses six different crime details in one run. The countermeasure: generate covert responses to irrelevant stimuli for each probe category. Hit rates were 82% in the guilty group; 18% in the countermeasure group. The average(More)
Subjects chose and pretended to steal one object from a box of nine. They then watched a visual display of verbal representations of objects including their chosen object or one of eight novel objects on each trial. They were told to count one of the novel objects and that although they were welcome to try to beat our test, they would be unable to avoid(More)
A new P300-based concealed information test is described. A rare probe or frequent irrelevant stimulus appears in the same trial in which a target or nontarget later appears. One response follows the first stimulus and uses the same button press regardless of stimulus type. A later second stimulus then appears: target or nontarget. The subject presses one(More)
The basic rationale of P300-based tests of concealed information compares responses to critical ('probe') and non-critical ('irrelevant') items. Accuracy, both in the laboratory and the field, is the degree to which responding to probes exceeds that to irrelevants. The present laboratory study assessed the influence of two factors on accuracy. The first,(More)
Functional magnetic resonance imaging (fMRI) studies have documented differences between deceptive and honest responses. Capitalizing on this research, companies marketing fMRI-based lie detection services have been founded, generating methodological and ethical concerns in scientific and legal communities. Critically, no fMRI study has examined directly(More)
Infusions of Chenopodium ambrosioides (L.) have been used for centuries in the Americas as a popular remedy against intestinal worm infections. The essential oil of Chenopodium ambrosioides contains high levels of ascaridole, which is a potent anthelmintic, but which has also been responsible for human fatalities, leading to its disuse. Almost 90% of the(More)
Two experimental, P3-based analog control question tests were run. In both, guilty subjects were presented with a set of seven phrases describing antisocial acts of which they were innocent, plus one phrase describing a guilty act (the analog relevant question), and one act to which a "yes" response (yes-target stimulus) was required to assure attention.(More)
Despite the P300-concealed information test's validity in detecting concealed memory when it is conducted immediately after the mock crime, whether the P300-CIT's detection efficiency is moderated by time delay remains unknown. Here, we conducted a mock crime study in which guilty participants were tested immediately after the mock crime or 1 month later.(More)
In an event-related potential (ERP)-based concealed information test (CIT), we investigated the effect of manipulated awareness of concealed information on the ERPs. Participants either committed a mock crime or not (guilty vs. innocent) before the CIT, and received feedback regarding either specific (high awareness) or general (low awareness) task(More)
UNLABELLED The aim of the present study was to compare two protocols and two information types on detection of concealed knowledge. Four independent groups of subjects were run. Two were tested on probe stimuli of a self-referring (AUTO) nature and two were tested on incidentally acquired details of a mock crime (MOCK). Each pair of groups was run either in(More)