Related Experiment Video
Updated: Jun 30, 2026
Assessment and Communication for People with Disorders of Consciousness
Published on: August 1, 2017
The Complex Trial Protocol (CTP): a new, countermeasure-resistant, accurate, P300-based method for detection of
J Peter Rosenfeld1, Elena Labkovsky, Michael Winograd
1Department of Psychology, Northwestern University, Evanston, Illinois 60208, USA. jp-rosenfeld@northwestern.edu
Abstract:
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 >90%. 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' values from .9 to 1.0.
