The impact of prior knowledge from participant instructions in a mock crime P300 Concealed Information Test.

In P300-Concealed Information Tests used with mock crime scenarios, the amount of detail revealed to a participant prior to the commission of the mock crime can have a serious impact on a study's validity. We predicted that exposure to crime details through instructions would bias detection rates toward enhanced sensitivity. In a 2 × 2 factorial design, participants were either informed (through mock crime instructions) or naïve as to the identity of a to-be-stolen item, and then either committed (guilty) or did not commit (innocent) the crime.

Review of recent studies and issues regarding the P300-based complex trial protocol for detection of concealed information.

In this review, the evolution of new P300-based protocols for detection of concealed information is summarized. The P300-based complex trial protocol (CTP) is described as one such countermeasure (CM)-resistant protocol. Recent lapses in diagnostic accuracy (from 90% to 75%) with CTPs applied to mock crime protocols are summarized, as well as recent enhancements to the CTP which have restored accuracy.

P900: a putative novel ERP component that indexes countermeasure use in the P300-based concealed information test.

Countermeasures pose a serious threat to the effectiveness of the Concealed Information Test (CIT). In a CIT experiment, Rosenfeld and Labkovsky in Psychophysiology 47(6):1002-1010, (2010) observed a previously unknown positive ERP component at about 900 ms post-stimulus at Fz and Cz that could potentially serve as an index of countermeasure use. Here, we explored the hypothesis that this component, termed P900, occurs in response to a signal that no further specific response is required in a trial, and could thus appear in countermeasure users that respond differentially depending on the stimulus that appears.

Mock crime application of the Complex Trial Protocol (CTP) P300-based concealed information test.

The Complex Trial Protocol (CTP), was shown to be an improvement over the previous "three stimulus" P300-based concealed information tests (CITs). Not only was it highly accurate with autobiographical information but was also resistant to the use of countermeasures (CMs). The current study applied the CTP to the detection of incidentally acquired information in a mock crime scenario.

Assigned versus random, countermeasure-like responses in the p300 based complex trial protocol for detection of deception: task demand effects.

We recently introduced an accurate and countermeasure resistant P300-based deception detection test called the complex trial protocol (Rosenfeld et al. in Psychophysiology 45(6):906-919, 2008). When subjects use countermeasures to all irrelevant items in the test, the probe P300 is increased rather than reduced (as it was in previous P300-based deception protocols), allowing detection of countermeasure users.

The effects of asymmetric vs. symmetric probability of targets following probe and irrelevant stimuli in the complex trial protocol for detection of concealed information with P300.

The complex trial protocol (CTP, [J.P. Rosenfeld, E.

The Complex Trial Protocol (CTP): a new, countermeasure-resistant, accurate, P300-based method for detection of concealed information.

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.