The Study Of Testing Suspects Based On The Difference Of Semantic Memory And Episode Memory In Event Related Potentials

Aim: People who know the case information usually include two categories,one is the suspect involved in the crime,and the other is the insider who understands the information through other method after the case occurs.This study uses cognitive neuroscience technology to explore the case of insider and perpetrators in event-related potentials(ERP)feature detection,analysis of brain potentials difference between the insider and the suspect of the crime,to help the public security assist the detection of cases.Method:This study adopts the experimental design which 2(subject type: crimer,insider)x 2(stimulus type: words,pictures)x 2(response mode: truthful response,deceptive response)mixed design.The type of subjects is the inter group factor,and the stimulus material and the type of reaction are intra group factors.26 Volunteers of this experiment were randomly divided into two groups,namely the subjects of insider and the subjects of crimer.The subjects of crimer simulation of burglary crime,the subjects of insider knows the case information by reading the text,then using ERPs detect the information for the subjects.Through E-prime software rendering the random stimulation sequence,adopting 64 Ag/AgCl electrode cap records the eeg data.And the eeg data were collected and using SCAN software for off-line processing and analysis these data.Results: In the reaction time,the subjects of insider(831.06±198.26ms)longer than the subjects of crimer(791.58±166.86ms),and the difference reached a significant level(P<0.01);No matter the subjects of insider or the subjects of crimer,the response time of deception reaction is greater than the truthful response,and the difference is all significant(P<0.01);In the accuracy rate,the main effect of different subjects does not reach a significant level(P=0.902).In terms of ERP data,the subjects of crimer generated by the Episode memory of ERP waveform more positive(400-800ms),the subjects of insider generated by the Semantic memory of ERP waveform more negative.The subjects of crimer and the subjects of insider average amplitude difference reached significant level(P=0.036),the subjects of crimer is higher than the the subjects of insider;the subjects of crimer induced P300 peak amplitude higher than the subjects of insider;in the intra group the average amplitude of the decetion reaction was greater than the truthful reaction,the subjects of crimer differences in different types of reactions reached significant level(P=0.025),the subjects of insider were also significant level(P=0.008).Conclusions: 1.The results of behavior data shows that the reaction time can be used as an effective indicator for judging different types of reactions and different types of memory,but the correct rate is not equal to the same effect.2.From the ERP waveform and the averageamplitude,different types of reaction can be distinguished by ERP waveform and average amplitude.3.Between two different stimultant materials-words and pictures,shows the "picture advantage effect".The pictures material induced the peak of N270 and P300 greater than words material,even pictures material average amplitude greater than words material,so the picture is more suitable for the ERP test as a stimulus than the word.4.Through the ERP waveform,the P300 amplitude and the average amplitude,can better judge the types of the person's memory,and then distinguish between the crimer and the cases of the insider.