An independent validation of the EEG-based complex trial protocol with autobiographical data and corroboration of its resistance to a cognitively charged countermeasure

The Complex Trial Protocol (CTP) is a P300-based Concealed Information Test (CIT). The theoretical underpinnings of the
CIT in the context of law enforcement usage are sound. The CTP is said to effectively discriminate individuals who recognize novel and meaningful stimuli and to be countermeasure resistant. Forty-five undergraduate students were assigned to three groups and instructed to perform a computer task using autobiographical data in connection to a mock burglary script.

P300 peak-to-peak amplitude differences between probe (surname) and irrelevant (patronymic foils) items accurately identified 100% (14/14) of Innocent Controls (IC), 94% (15/16) of Simply Guilty (SG) participants, and 93% (14/15) of Guilty Countermeasure (GCM) subjects who were asked to counter all stimuli by mentally counting backwards continuously during their test presentation. Increased number of mistakes during the test, from combined cognitive erroneous responses to pop quizzes and behavioral errors with button presses, significantly discriminated GCM from IC and SG individuals. GCM participants committed more errors than IC and SG which did not differ from one another. Reaction Time (RT) was only significant between GCM and IC groups. Implications for forensic issues are discussed.