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 button for a target, another for a nontarget. A P300 to the first stimulus indicates probe recognition. One group was tested in 3 weeks for denied recognition of familiar information. Weeks 1 and 3 were guilty conditions; Week 2 was a countermeasure (CM) condition. The probe-irrelevant differences were significant in all weeks, and percent hits were 490%. Attempted CM use was detectable via elevated reaction time to the first stimulus. In a replication, results were similar. False positive rates for both studies varied from 0 to .08, yielding J. B. Grier (1971) A 0 values from .9 to 1.0.

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Here, a rare probe or frequent irrelevant stimulus (S1) appeared in the first part of the trial, followed by either a target or nontarget (S2) in the second. Subjects randomly pressed one of five buttons to S1 to signal seeing it. Then they pressed one of two buttons for nontargets or targets. We tested three groups: simple guilty (SG), in which one stimulus was the subject's birth date (Probe); innocent (IN) in which all date stimuli were irrelevant; and Countermeasure (CM), like SG but subjects performed mental CMs to 2 of 4 irrelevants. Bootstrapped-based hit rates in the SG group=100%, based on probe versus all four averaged irrelevants (Iall), or based on probe versus RT-screened maximum irrelevant (Imax). In the IN group there was one false positive (8%, Probe vs. Iall) or none (0%, Probe vs. Imax). In the CM group, 100% were detected based on Probe versus Iall (92% based on Probe vs Imax). A new event-related potential at Fz and Cz at 900 ms indexed CM use.

Previous research indicated that the skin conductance response of the autonomic nervous system 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 P300 tests based on the three-stimulus protocol for detection of cognitive malingering (although these are not the same as CITs). The present report is the first attempt to study the effect of financial motivation on the P300-based Complex Trial Protocol using both episodic and semantic memory probe and irrelevant stimuli. The Test of Memory Malingering (TOMM) was used to validate behavioral differences between the two groups we created by offering one (paid) group but not another (unpaid) group a financial reward for beating our tests. Group behavioral differences on the TOMM did confirm group manipulations. Probe-minus-irrelevant P300 differences did not differ between groups, although as previously, semantic memory-evoked P300s were larger than episodic memory-evoked P300s.

Purpose. P300 memory detection test is a neuroscientific procedure to assess memories stored in the brain. P300 memory detection can and is currently applied to assess criminal suspects on recognition of critical crime information. Contrasting memory detection with lie detection, researchers have argued that P300 memory detection does not involve deception. We empirically investigated this argument by manipulating deception between groups. Methods. Thirty-four community volunteers participated in a P300 memory detection test, answering either deceptively (deceptive condition) or truthfully (truth condition) to their own name. Results. P300 memory detection was significant in the truth condition, indicating that deceptive responding is not a prerequisite for valid P300 memory detection. However, there were clear indications that deceptive responding improved memory detection. Conclusions. Deception seems involved in the P300 memory detection test; and deceptive responding may add to test accuracy