However, in 2006, J. Peter Rosenfeld and col-
leagues reported that a second-generation P300-
based deception test using a wholly novel protocol
was accurate and highly resistant to CMs. More than
100 subjects have been studied to date, and the
accuracy rates have been 90% to 100% in many
experiments, dropping by only 0% to 10% with CM
use. Moreover, a new feature built into this new pro-
tocol alerts operators about CM use. In the new
protocol—called the Complex Trial Protocol (CTP),
two stimuli are presented on each trial, and there are
four possible trial types. The first stimulus is either
a probe or an irrelevant, and the subject responds
with one simple behavioral acknowledgment that
the stimulus has been seen. About 1 to 1.5 s later, a
second stimulus is presented, which is either a rede-
fined target or not one. The subject here signals tar-
get or nontarget. The subject’s absolute behavioral
reaction time to the first stimulus is significantly
increased if a CM is being used, and the reaction
time to irrelevants, which without a CM is less than
or the same as that to probes, is usually increased to
much greater than probe reaction time if a CM
accompanies the irrelevant. Thus, occasionally suc-
cessful CM use or attempted but unsuccessful CM
use has always been detected. The probe P300
amplitude actually increasesduring CM use (unlike
what is seen with the older protocol based on three
trial types—probe, irrelevant, or target). Such an
increase means that the CTP is still likely to see a
probe-irrelevant difference even if the irrelevant
P300 increases, as expected, during CM use. It
appears that this new protocol is powerful because
its multiple demands made on the subject force
attention on the key stimuli, thus enhancing P300
responses to them.
Other brain-activity-based dependent indices of
deception have been suggested and researched in pre-
liminary ways. These approaches have different theo-
retical foundations. Dr. J. Peter Rosenfeld and colleagues
have also examined the P300 amplitude distribution
(not simple amplitude) across the scalp (a kind of
“brain map”) as a promising new index of deception.
The motivation for pursuing this new approach is,
again, the possibility of removing CMs. It was simple
to develop CMs for the earlier P300-amplitude-based
protocols because the antecedents of P300 ampli-
tude—rareness and meaningfulness—are relatively
well-known. If one knows the antecedents of P300,
then one knows how to manipulate it. On the otherhand, very little is known about how to manipulate the
amplitude distribution across the scalp, thus facilitat-
ing the creation of a CM method.J. Peter RosenfeldSee alsoDetection of Deception in Adults; Polygraph and
Polygraph TechniquesFurther Readings
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