Increasing the number of irrelevant stimuli increases ability to detect countermeasures to the P300‐based Complex Trial Protocol for concealed information detection

Abstract

Based on P300 data, 100% of the simple guilty (no countermeasure use) and 92% of the innocent subjects were correctly identified as having or not having concealed information. In the countermeasure groups, detection rates varied from 71% to 92% across the different groups. Notably, in the present study with eight irrelevant items, simultaneous countermeasure use was indicated by elevated RT in the 50% and 75% countermeasure proportion groups, which it was not, previously, with 50% (two) countermeasures and four irrelevants.

The first independent study on the complex trial protocol version of the P300-based concealed information test: Corroboration of previous findings and highlights on vulnerabilities

“…Importantly, we also found, same as previous studies (Hu et al, 2012;Labkovsky and Rosenfeld, 2012;Rosenfeld et al, 2008;Rosenfeld and Labkovsky, 2010;Winograd and Rosenfeld, 2011), that the P vs. Iall measure (probe compared to all irrelevant items) provided high detection rates not only in the SG group (AUC = .98), but also in both CM groups (AUC = .93 using the original, and AUC = .94 using the new countermeasures), with no significant differences between the three groups. This also makes our study the first to show that the results of the P vs. Iall and the P vs. Imax measures, which have been shown to provide very similar accuracies in all previous experiments (Meixner et al, 2009;Rosenfeld, 2014, 2011;Rosenfeld et al, 2008;Rosenfeld and Labkovsky, 2010), can in fact differ greatly.…”

“…However, one of these articles (Hu et al, 2012) did report that, in the case of 2 countered irrelevant items out of 8, the P300 responses to probe and countered irrelevant items were significantly larger than those of non-countered irrelevant items, while, in the cases of 4 and 6 countered irrelevant items out of 8, only the probe but not the countered irrelevant items evoked P300 responses significantly larger than non-countered irrelevant items (Hu et al, 2012, p. 88).…”

“…Two articles on the CTP have been published that have examined the effect of countermeasures (covert responses) against less than the half of the irrelevant items, but neither of these reported P vs. Imax measures (Hu et al, 2012;Labkovsky and Rosenfeld, 2012).…”

“…As several studies seemed to prove the CTP highly countermeasure-resistant (Hu et al, 2012;Labkovsky and Rosenfeld, 2012;Rosenfeld et al, 2008;Rosenfeld and Labkovsky, 2010;Winograd and Rosenfeld, 2011), more recent research focused on other areas (optimization of parameters, etc., Hu et al, 2013;Meixner and Rosenfeld, 2014;Rosenfeld et al, 2015aRosenfeld et al, , 2015bWinograd and Rosenfeld, 2014). However, these studies have been using two kinds of P300-based measurements for the classification of participants as guilty or innocent, namely, the "P vs.…”

“…Thus, to target a small, two-item group of irrelevant items, the original countermeasures could be used in the following way: silently articulating one specific name whenever one of the two small-group irrelevant item appears, and another specific name whenever the other small-group irrelevant item appears, while omitting covert responses whenever any of the other items appear (exactly as in the following studies: Hu et al, 2012;Labkovsky and Rosenfeld, 2012;Rosenfeld and Labkovsky, 2010).…”