Effect Of The Consistency Of Stimulus And Background On The Detection Efficiency Of The Complex Trial Protocol

The Complex Trial Protocol(CTP)first determines whether the subject has the memory of crime-related information by using psychophysiological measurements and then determines whether he or she is aware of the case based on the measurement results.However,at present,the accuracy rate of CTP measured by the P300 indicator in detecting crime-related information was only over 80% and it’s necessary to further improve the scientificity and accuracy of the polygraph method.Besides,it was still controversial whether there is an environmental context-dependency effects in recognition.Therefore,the present study attempts to explore the effect of the consistency of stimulus and background on the detection efficiency of the CTP and examine whether there is an environmental context-dependency effects in recognition.Participants were required to complete a CTP test consisting of four blocks after completing the mock crime task of stealing the ring.In each of the four different blocks,the pictures of the probe/irrelevant stimuli on the blank background,on the old crime spot background,on the old non-crime spot background,and the new non-crime spot background were presented respectively in the first part of each trial,and participants were required to perform the perceived response after seeing the probe/irrelevant stimuli clearly.Target/non-target stimuli were presented randomly in the second part of each trial,and participants were required to perform the discriminative response after seeing the target/non-target stimuli.It is a consistent condition that the probe on the old crime spot background.While it is inconsistent condition that the probe on the old non-crime spot background and the probe on the new non-crime spot background.It is a neutral condition that the probe on the blank background.The results found that:(1)In terms of the difference of probe minus irrelevant P300 amplitude,the bootstrapped difference of probe minus irrelevant P300 amplitude,and the bootstrapped iteration of probe P300 amplitude exceeding irrelevant P300 amplitude,the condition of probe/irrelevant stimuli on the old crime spot background was significantly larger than the conditions of probe/irrelevant stimuli on the other backgrounds;(2)the probe/irrelevant stimuli on the old crime spot background has a significantly higher detection rate of "guilty person"(18/24)than on the blank background(7/24),on the old non-crime spot background(6/24),and on the new non-crime spot background(4/24);(3)when the probe/irrelevant stimuli on the old crime spot background,the AUC(0.896)of the CTP to identify the guilty from the innocent was significantly better than on the other backgrounds;(4)the probe on the old crime spot background has a significantly larger P300 amplitude than the probe on the old non-crime spot background;(5)the probe on the old non-crime spot background and on the new non-crime spot background have a significantly larger N200 amplitude than the probe on the old crime spot background and on the blank background.The above results showed that:(1)the consistency of the probe and the background can improve the detection efficiency of CTP.In the future,it may be considered to present the probe/irrelevant stimulus on the old crime spot background in the first part of the CTP test to improve the detection efficiency of CTP;(2)there is an environmental context-dependency effects in recognition;(3)the inconsistency of the probe and the background will evoke greater cognitive conflict response.