Deception is a complex cognitive activity that often appears in daily life. A largenumber of studies have shown that deception will produce physiological clues differentfrom telling the truth. These differences are reflected in the autonomic nervous systemand central nervous system, and the brain activities induced by active deception andpassive deception are also different. In the laboratory environment, the subjectiveintention of deception is generally manipulated by money reward. However, the passivedeception paradigm mainly used in the previous research based on P300 deceptiondetection can not well induce the subjective intention of deception, and the ecologicalvalidity is low. Therefore, it is necessary to adopt the experimental paradigm ofinducing subjective deception intention to further investigate the effectiveness of P300deception detection.
In this study, the combination of a mock crime paradigm and complex trialprotocol (CTP) was used to operate the subjects' subjective deception intention throughmonetary reward. Under the condition of subjects' intentional deception, the effects ofdifferent ways and intensity of monetary reward on the effectiveness of P300 deceptiondetection were investigated through EEG Technology. This study includes two ERPStudies (including three ERP experiments).
Study 1 used the mock crime paradigm and CTP paradigm to investigate theimpact of reward on P300 in the CTP paradigm. Experiment 1 mainly investigated theP300 difference between "the innocent", "the guilty", and "the informed innocent"without feedback; The results showed that there was no significant difference in probeP300 and irrelevant P300 between the guilty group and the informed innocent group,but the CIT effect was significantly greater than that between the informed innocentgroup and the innocent group, which indicated that the processing degree of probestimulation may be different between the guilty and the informed innocent. Experiment2 mainly investigated the difference of P300 between "the guilty" and "the informedinnocent" based on single-trial feedback.; The results showed that there was no significant difference between the two groups of probe P300, but there were significantdifferences in CIT effect and CNV, suggesting that cognitive load may affect thescreening of guilty and informed innocent people. Through the analysis of thedifferences between experiment 1 and experiment 2, the effects of the two rewardmethods on P300 in the CTP paradigm were compared. The results show that the CITeffect of the guilty group and the informed innocent group in Experiment 1 issignificantly higher than that of the guilty group and the informed innocent group inExperiment 2, which shows that the reward methods can affect the CIT effect in theCTP paradigm.
Study 2 used the same mock crime paradigm and CTP paradigm as study 1 toinvestigate the impact of monetary reward and punishment intensity on P300.Experiment 3 manipulated the reward and punishment intensity by changing the rewardand punishment amount. Through the analysis of the difference between the two groups,the difference of P300 under the two reward and punishment intensities was compared.The results showed that the difference of CIT effect between the two groups and thedifference of CNV on the two stimuli showed that the reward and punishment intensitymay affect the CIT effect by affecting the cognitive load of the subjects.
By exploring the influence of money reward on the effectiveness of P300 liedetection under the condition of active deception, this study can enrich and improvethe relevant theoretical basis of P300 lie detection, help to further improve theeffectiveness of deception detection, and make it better used as an auxiliary tool in thefield of the criminal investigation.
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