犯罪知识测试(GKT)测谎模式及其变式的实验研究

目的 :在以测谎实验验证犯罪知识测试 (GKT)测谎模式的认知原理 ,同时探索GKT在变式状况下的运用价值 ,并从GKT模式的认知原理出发 ,讨论目前广泛运用于标准GKT测试的Lykken判定法所存在的问题 ,以期找到更符合GKT模式认知原理的科学判定法。方法 :以 4 0名大学生为被试 ,中性的无意义字母串为测试材料 ,皮肤电反应为指标 ,在无动机性指导语下进行测谎测试。结果 :运用标准GKT测试Lykken判定法 ,在知道犯罪组关键信息而不知道是否存在无辜受测者的情况下 ,对“罪犯”的判定准确率为 73% ;运用“最高原则、邻近原则”判定法 ,在知道受测者均为“罪犯” ,而不知道其关键信息的情况下 ,将关键信息的模糊范围从 5个信息缩小到 2个 ,其缩小范围的判定准确率为 78.4 %。结论 :标准GKT测试的准确率达到以往国外同类范式研究的最高准确率 ,证实了GKT模式的刺激意义性定向反射认知原理的科学性 ;在不明线索下运用GKT变式缩小关键信息范围 (GKT变式 )具有可行性和实际运用价值     

Innocence, Information, and the Guilty Knowledge Test in the Detection of Deception

The purpose of this detection of deception experiment was to study the assumption of the Guilty Knowledge Test that subjects with guilty knowledge will be classed as guilty by the test regardless of their actual guilt or innocence. Prior to a polygraph examination, three groups of innocent subjects were given the same crime-relevant information as members of a group guilty of a mock crime. These innocent subjects either witnessed the crime, were told the crime details, or carried out innocent activities involving crime-relevant information. An additional group of innocent subjects had no crime-relevant information. Analysis of the Guilty Knowledge Test results showed that the detection scores of guilty subjects were higher than those in any of the innocent groups. In fact, with the exception of the innocent activities group, the innocent informed subjects did not differ from those in the uninformed group. The major conclusion is that subjects may have crime-relevant information and not be classed, based on the detection scores, as guilty.     

人格测验中测谎方法研究概述

目的探讨人格测验中的测谎方法。方法在国内外相关文献的基础上,系统地总结各种方法,分析它们的优势和不足。结果人格测验的测谎方法,主要包括作假识别量表、项目反应、反应时识别及逻辑陷阱等。结论由于文化或功用等因素,有些西方测谎题不适用中国被试,不宜采用。后3种方法操作起来十分复杂,而且由于对说谎的内部机制了解较少,制约了这些技术的发展,因此职业选拔情境下的作假识别工具亟待开发。     

Salience of Guilty Knowledge Test items affects accuracy in realistic mock crimes.

Guilty Knowledge Test measuring electrodermal reactions was carried out in order to investigate the quality of different questions and the validity of the test in a situation that resembled a true crime. Fifty participants were randomly assigned to commit one of two realistic mock crimes, and were later tested with GKTs concerning both the crime they had enacted and the one they had no knowledge of. Different scoring systems (SCRs and peak amplitudes as well as raw and standardised scores) were employed and compared when analyzing the results. Although there were some false positives, the test was able to differentiate between the groups of guilty and innocent participants. With the best scoring systems, the test was able to classify up to 84% of the innocent and up to 76% of the guilty correctly according to a logistic regression analysis. ROC areas reflecting these same results reached values above .80. Questions on matters that demanded the participants' attention and were easier to remember had better discriminative power. With nearly all scoring methods, there was a significant interaction between the salience of the relevant items and the guilt of the participants. Participants reacted more strongly to salient relevant items when they were guilty, while no different reactions were observed for the non-salient items between guilty and innocent participants. It is suggested that, although the Guilty Knowledge Test appears to be a valid measure of guilty knowledge even in crimes that are close to real crimes, the principles on which guilty knowledge test questions are constructed should be more clearly specified.     

The Roles of Deception, Intention to Deceive, and Motivation to Avoid Detection in the Psychophysiological Detection of Guilty Knowledge

The present study focused on electrodermal differentiation between relevant and neutral items in the Guilty Knowledge paradigm. Three factors were varied in a between-subjects design. The role of deception was examined by varying the type of verbal answer to the questions ("yes," "no," and remaining silent). The intention to deceive factor was examined by contrasting subjects told to delay their answer ("yes" or "no") with those told to produce their answer immediately. Finally, motivation to avoid detection was manipulated by having half the subjects monetarily rewarded for an important (ego relevant) detection task (high motivation), whereas the remaining subjects were neither rewarded nor told that the task was important. The results indicated that a deceptive answer ("no") to the relevant question was associated with an increased differential skin conductance responsivity, but better than chance detection rates were obtained with truthful ("yes") and silent conditions. Equal and significant detection rates were observed when the responses were computed immediately following question presentation, whether the subjects had answered immediately or had delayed their answers. In contrast, differential electrodermal responsivity to the delayed answers was markedly attenuated. The motivation factor had no main or interactive effects on differential responsivity. The present results, together with those obtained in previous studies, suggest that whereas deception is neither a necessary nor a sufficient condition for psychophysiological detection, it may facilitate detection. Possible mechanisms through which such a facilitation could occur were considered.