The effects of practicing a novel countermeasure on both the semantic and episodic memory-based complex trial protocols.

This study applied a countermeasure-resistant version of the Concealed Information Test - the Complex Trial Protocol (CTP) - in an information recognition scenario. We replicated and extended the effects of a novel countermeasure developed by Lukács et al., (2016) on both Semantic and Episodic CTPs. We measured participants' response time and P300 event-related potential to rare, crime-relevant probe stimuli, or frequent, non-crime-relevant irrelevant stimuli in two ways: 1) probe vs the average of all irrelevants (PvIall), and 2) probe vs the maximum irrelevant (PvImax). We hypothesized that countermeasure use would only impair information recognition (as indexed by P300) when participants had practiced the countermeasure beforehand. We further hypothesized that recognition of less salient, Episodic information (i.e., jewelry items from a mock crime) would be impaired by countermeasure use more than the recognition of highly salient, Semantic information (i.e., birthdates). Individual diagnostics based on the area under the receiver operating characteristic curve (Semantic CTP: practice n = 22, non-practice n = 23; Episodic CTP: practice n = 19, non-practice n = 18) revealed that the Semantic CTP was affected by the novel countermeasure, but both PvIall and PvImax analyses remained diagnostically useful. The Episodic CTP's performance, however, was reduced to chance, regardless of practice or analysis type. These results are important for both the field of deception detection and the CTP literature. Research on improvements to the Episodic CTP is required.

The enhancing effect of incongruent verbal priming stimuli on the CIT effect with pictorial probes in the P300-based complex trial protocol.

Previous research (Herring et al., 2011) indicated that certain types of incongruent verbal priming enhance responding to the subsequent (primed) stimuli. By priming participants in a P300-based Concealed Information Test (CIT), we examined the possible enhancement effects of priming stimuli in the P300 based Complex Trial Protocol (CTP) for face recognition. Participants were divided into two groups: one group with priming and one control group without. The probe (Pr) and irrelevants (Iall) of the two groups were faces, namely, pictures of the actor Tom Cruise (Pr) and of other unknown faces (Iall). One group had priming before Pr/Iall and one control group had no priming. The priming group was called the non-identical priming (NIP) group in which the verbal priming item (the name, "Bill Smith") is identical with neither Pr nor any of the Ialls. The group without priming is the control group which is called the non-priming group (NP) that simply experiences the basic Complex Trial Protocol. Results were that non-identical priming produced larger CIT effects than the control group, which is consistent with earlier findings. Also, the amplitude of the probe of the NIP group is larger than that of the NP group, while their irrelevants didn't show any significant difference. This means that the incongruent verbal priming did enhance the P300 CIT effect for the probe, which could further improve the accuracy of CTP for the concealed information test.

The effect of retroactive memory interference on the P300-based Complex Trial Protocol (CTP).

In a P300-based concealed information test (CIT), an increased response to a crime-related "probe" item of interest suggests concealed knowledge. Because the CIT's detection ability is based on knowledgeable parties recognizing the key item, weakening the crime memory might decrease probe identifiability and reduce diagnostic power. Research on retroactive memory interference (RI) has shown that acquiring new information after encoding a memory can degrade the original memory, which suggests that RI might pose a threat to CITs. To test this, Gronau et al. (2015) had participants complete a mock-crime, followed by either a control task or a RI manipulation task, intended to impair the crime memory. Both the simple guilty control and RI groups were subdivided into three time delay conditions: 1/3 of participants immediately completed the task and CIT, another 1/3 completed the task and returned a week later for the CIT, and the remaining participants completed both the task and CIT a week later. Results showed that RI reduced memory of crime details and skin conductance responses, while respiration line length was unaffected. Here, we extend Gronau et al. (2015), using the Complex Trial Protocol (CTP) version of the P300-based CIT, to investigate the influence of RI on recognition. The CIT effect was obvious in all six group × time delay subconditions, as evidenced by their significantly larger probe vs. irrelevant amplitudes, high percentage of bootstrapped iterations where probe > irrelevants, bootstrapped mean amplitude differences, and satisfactory hit rates. However, these indices of the CIT effect did not differ based on group or time delay, as was the case for target response error rates and P300 latencies. The only outcome of interest to vary by group or time delay was behavioral response times: both probe and combined irrelevant responses were delayed in the control (simple guilty) group. Thus, the evidence suggests that the RI manipulation used here does not threaten the P300-based CTP's accuracy. Results are considered as they compare to previous work, and limitations and possible explanations for our results are discussed.

Moderate financial incentive does not appear to influence the P300 Concealed Information Test (CIT) effect in the Complex Trial Protocol (CTP) version of the CIT in a forensic scenario, while affecting P300 peak latencies and behavior.

Previous research indicated that the skin conductance response (SCR) of the Autonomic Nervous System (ANS) in the Concealed Information Test (CIT) is typically increased in subjects who are financially and otherwise incentivized to defeat the CIT (the paradoxical "motivational impairment" effect). This is not the case for RT-based CITs, nor for P300 tests based on the 3-stimulus protocol or Complex Trial Protocol for detection of cognitive malingering (although these are not the same as forensic CITs). The present report extends earlier studies of malingerers by running five groups of subjects (15-16 per group yielding 78 total) in a mock crime (forensic) scenario: paid (to beat the test) and unpaid, instructed and uninstructed, and simply guilty. There was no evidence that the "CIT effect" (probe-minus-irrelevant P300 differences) differed among groups, although behavioral differences among groups were seen.