P900: A putative novel ERP component that indexes countermeasure use in the P300-based concealed information test

John B. Meixner*, Elena Labkovsky, J. Peter Rosenfeld, Michael Winograd, Alexander Sokolovsky, Jeff Weishaar, Tim Ullmann

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


Countermeasures pose a serious threat to the effectiveness of the Concealed Information Test (CIT). In a CIT experiment, Rosenfeld and Labkovsky in Psychophysiology 47(6):1002-1010, (2010) observed a previously unknown positive ERP component at about 900 ms post-stimulus at Fz and Cz that could potentially serve as an index of countermeasure use. Here, we explored the hypothesis that this component, termed P900, occurs in response to a signal that no further specific response is required in a trial, and could thus appear in countermeasure users that respond differentially depending on the stimulus that appears. In the present experiments, subjects viewed four non-meaningful (irrelevant) dates and one oddball date. In three experiments, we examined P900's antecedent conditions. In the first, the unique item was a personally relevant oddball (the subject's birthdate). In a second, the unique item was a non-personally relevant oddball (an irrelevant date in a unique font color). In a third, all dates were irrelevant. We speculated that the presence of an oddball would not be necessary for P900. All participants made countermeasure-like responses following two specific irrelevant dates. As hypothesized, P900s were seen to non-responded-to irrelevant and oddball stimuli in all subjects but not to responded-to irrelevant stimuli, and the presence of an oddball was not necessary for elicitation of P900. This finding has potential application in deception settings - the presence of a P300 accompanied by the presence of a P900 in response to non-countered stimuli could provide evidence of incriminating knowledge accompanied by the attempt to use countermeasures to evade detection.

Original languageEnglish (US)
Pages (from-to)121-132
Number of pages12
JournalApplied Psychophysiology Biofeedback
Issue number2
StatePublished - Jun 2013


  • Countermeasures
  • ERP
  • P900
  • Readiness potential

ASJC Scopus subject areas

  • Neuropsychology and Physiological Psychology
  • Applied Psychology


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