The New Coplex Trial Protocol for Deception Detection ：新的復(fù)雜的試驗協(xié)議欺騙檢測

1、j. peter rosenfeld, john meixner, michael winograd, elena labkovsky, alex haynes, northwestern universityaka”guilty knowledge” test.physiological responses accompany recognition of information known only by guilty perps and authorities.responses are traditionally autonomic hr, gsrbut we use brain wa

2、ves:an endogenous, event-related potential (erp)positive polarity (down in illinois).amp = f(1/stim. probability, meaningfulness)80% to 95% correct detection rates.but. *rosenfeld et al. (2004) and mertens, allen et al. (2008):these methods are vulnerable to counter-measures (cms) via turning is int

3、o covert ts.when you see a specific irrelevant, secretly make some specific response, mental/physical.after all, if you can make special response to target on instruction from operator, you can secretly instruct yourself.irrelevant becomes secret target. it makes big p300. if p = i, no diagnosis.2 t

4、asks for each trial: 1. implicit probe recognition vs. 2. explicit target/non-target discrimination hypothesized result: mutual interference of 2 tasks more task demand reduced p300 to p. cms hurt old test. results from rosenfeld et al. (2004): farwell-donchin paradigm(bad and bcad are 2 analysis me

5、thods.)diagnoses of guiltyguilty groupinnocent groupcm group 9/11(82%)1/11(9%) 2/11(18%)amplitude difference (bad) method,p=.1cross-correlation(bc-ad) method, p=.16/11(54%)0/11(0%)6/11(54%)week bad* bc-ad* 1: no cm 12/13(.92) 9/13(.69)2: cm 6/12(.50) 3/12(.25)3: no cm 7/12(.58) 3/12(.25)*note: bc-ad

6、 and bad are 2 kinds of analytic bootstrap procedures. 2 stimuli, separated by about 1 s, per trial,s1; either p or i.then.s2 ; either t or nt. *there is no conflicting discrimination task when p is presented, so p300 to probe is expected to be as large as possible due to ps salience, which should l

7、ead to good detection; 90-100 % in rosenfeld et al.(2008) with autobiographical information. it is also cm resistant. (delayed t/nt still holds attention.) * “i saw it” response to s1. rt indexes cm use.week hit rate week 1 (no cm): 11/12 (92%) week 2 (cm): 10/11 (91%) week 3 (no cm): 11/12 (92%) 3

8、groups (n=12) simple guilty (sg), countermeasure (cm), innocent control (ic) all subjects first participated in a baseline reaction time (rt) test in which they chose a playing card. sg and cm subjects then committed a mock crime. subjects stole a ring out of an envelope in a professors mailbox. all

9、 subjects were then tested for knowledge of the item that was stolen. there were 1 p (the ring) and 6 i( necklace,watch,etc). cm subjects executed covert assigned responses to irrelevant stimuli in an attempt to evoke p300s to these stimuli to try and beat the probe vs. irrelevant p300 comparison. c

10、ondition detections percentage sg 10/12 83 cm 12/12 100 ic 1/12 8unlike 3-sp, the ctp is highly sensitive at detecting incidentally acquired concealed knowledge in a mock-crime (as with autobiographical knowledge).another advantage of the ctp vs 3-sp or polygraph cit: resistance to cm use. cm use pr

11、oduces a large increase in rt between the baseline and test block, and within test block, probe vs irrelevant rt .5-button i saw it box. the subject is instructed to press, at random*, one of the 5 buttons. we hoped that this would make cms harder to do. it didnt, but we caught the cm users anyway.a

12、utobiographical information (birthdates): one p and 4 i (other, non-meaningful dates).3 groups as before: sg,cm, ic.new: mental cms to only 2 of the 4 irrelevants: say to yourself your first name or your last name. these are assigned prior to run.only one block per group (no baseline).group bt/iall.

13、9 bt/imax.9 sg 13/13 (100%) 13/13 (100%) ic 1/13 (7.6%) 1/13 (7.6%)cm 12/12 (100%) 10/12 (83%)rt still nicely represents cm use within a block. rosenfeld & labkovskyjohn meixner & peter rosenfeldhow do you catch bad guys before crimes are committed, and before you know what was done, where,

14、when? +experimental guilty subjects come to lab and study 3 brochures dealing with pros & cons of 1) what city to attack, 2) what method to use, 3) what date to attack on for later 3 blocks of ctp tests. + then they write letter to boss with recommendations. + innocent controls study vacation br

15、ochures, write recommendation letter to parents/room-mates.a mock terrorism application of the p300-based concealed information testdepartment of psychology, northwestern university, evanston, iliallguilty1000100095599699490994599799998591290396612/12auc = 1.0innocent64861059861115047560055558669039

16、06445460/12imaxguilty98599988989894669867795990888866783786312/12auc = 1.0innocent287416476430172843652502173821292152890/12blind imaxguilty98599889289394376170296190788669884287210/12auc = .979innocent6036026496056895475365695657066507026190/12table 1. individual bootstrap detection rates. numbers

17、indicate the average number of iterations (across all three blocks) of the bootstrap process in which probe was greater than iall or imax. blind imax numbers indicate the average number of iterations in which the largest single item (probe or irrelevant) was greater than the second largest single item. mean values for each column are displayed in bold above detection rates.ctp