Meta-analytically quantifying the reliability and biasability of forensic experts

Abstract:  In this paper we employ meta-analytic procedures and estimate effect sizes indexing the degree of reliability and biasability of forensic experts. The data are based on within-expert comparisons, whereby the same expert unknowingly makes judgments on the same data at different times. This allows us to take robust measurements and conduct analyses that compare variances within the same experts, and thus to carefully quantify the degree of consistency and objectivity that underlie expert performance and decision making. To achieve consistency, experts must be reliable, at least in the very basic sense that an expert makes the same decision when the same data are presented in the same circumstances, and thus be consistent with themselves. To achieve objectivity, experts must focus only on the data and ignore irrelevant information, and thus be unbiasable by extraneous context. The analyses show that experts are not totally reliable nor are they unbiasable. These findings are based on fingerprint experts decision making, but because this domain is so well established, they apply equally well (if not more) to all other less established forensic domains.     

领导决策风格量表的修订与应用研究

领导者的决策风格是领导班子配置的重要依据。罗的决策风格量表是目前国际上使用较为广泛的决策风格量表之一。本项研究依据心理测量学的有关原理和罗的决策风格量表编制的有关理论 ,从我国国情出发 ,对罗的决策风格量表进行了修订 ,并根据各类决策风格与人的个性因素之间的关系 ,对修订后的领导决策风格量表进行信度和效度的检验 ,为领导人才的开发提供了有用的工具     

A parameter study regarding the IBIS correlator

The electronic system IBIS has been used by numerous agencies worldwide as the standard tool to compare firearm markings on bullets and fired cartridges. There is a general interest among users concerning the likelihood with which the IBIS correlator may locate hits in its databases. Test results of the performance under different test conditions have been published in various papers. Experience has also been gained with the IBIS system from years of practical usage. All of these findings are difficult to compare with each other. No systematic presentation exists that actually shows the parameters upon which the success rate of the IBIS correlator depends. There has also been no mention of what values these parameters take on during each test. This paper first generally defines the success and error rates of the IBIS correlator. The parameters used will be discussed. Results of previously published tests will be re-examined based on this methodology. An illustrative form of presentation for the success rate of an electronic comparison system will also be suggested. It will be shown that the success rate of the IBIS correlator highly depends on the quality of the firearms-generated markings. It increases with the number of considered mark types, the number of available signatures per firearm, and the number of items inspected in the hit list. The success rate decreases with the database size. The paper will conclude with a series of practical recommendations for the setting up and successful operation of an electronic collection of ballistic evidence.     

An experience report regarding the performance of the IBIS correlator

The majority of published experimental evaluations of the performance of the IBIS system are based on very specific conditions, mainly considering IBIS as a tool to create a "ballistic database." No recent reports were found covering the performance of the IBIS system to search an open case file of realistic structure. In this paper, the performance of the IBIS correlator will be evaluated, based on four different data sources that predominantly concern the operation of the central collection of evidence ammunition of the Federal Criminal Police Office (BKA), Germany. The results allow a conclusion on the success and error rates to be expected of the IBIS correlator in a realistic OCFDB ("open case file database") environment, given certain conditions. It was found that success rates of 75-95% for cartridge case comparisons and 50-75% for bullet comparisons can be achieved in practice. Recommendations for a most efficient way to operate the IBIS electronic comparison system will be presented based on the results of the evaluations. The terms and definitions in this report completely correspond with the definitions in an earlier article. Familiarity with this article is therefore absolutely necessary to fully understand many of the statements presented here.     

司法鉴定人自主判断权的理性思辨——以法医临床司法鉴定为视角

法医临床司法鉴定领域中,标准规定笼统、术语弹性较大以及技术规范差异等因素,使得鉴定人在一定程度上享有对某些特定问题的自主判断权。自主判断权的应用有其存在的必要性,但需通过必要的措施予以约束与制衡。否则,很难保证司法鉴定的科学、客观、公正,同时也会损害作为证据的司法鉴定意见的证明效力,妨碍司法公正的实现。     

Visual attention and expertise for forensic signature analysis

Eye tracking was used to measure visual attention of nine forensic document examiners (FDEs) and 12 control subjects on a blind signature comparison trial. Subjects evaluated 32 questioned signatures (16 genuine, eight disguised, and eight forged) which were compared, on screen, with four known signatures of the specimen provider while their eye movements, response times, and opinions were recorded. FDEs' opinions were significantly more accurate than controls, providing further evidence of FDE expertise. Both control and FDE subjects looked at signature features in a very similar way and the difference in the accuracy of their opinions can be accounted for by different cognitive processing of the visual information that they extract from the images. In a separate experiment the FDEs re-examined a reordered set of the same 32 questioned signatures. In this phase each signature was presented for only 100 msec to test if eye movements are relevant in forming opinions; performance significantly dropped, but not to chance levels indicating that the examination process comprises a combination of both global and local feature extraction strategies.     

An insight into forensic document examiner expertise for discriminating between forged and disguised signatures

It has previously been shown that forensic document examiners (FDEs) have expertise in providing opinions about whether questioned signatures are genuine or simulated. This study extends the exploration of FDE expertise by evaluating the performance of eight FDEs and 12 control subjects at identifying signatures as either forgeries or the disguised writing of a specimen provider. Subject eye movements and response times were recorded with a Tobii 1750 eye tracker during the signature evaluations. Using a penalty scoring system, FDEs performed significantly better than control subjects (t = 2.465, p = 0.024), with one FDE able to correctly call 13 of the 16 test stimuli (and three inconclusive calls). An analysis of eye movement search patterns by the subjects indicated that a very similar search strategy was employed by both groups, suggesting that visual inspection of signatures is mediated by a bottom up search strategy. However, FDEs spent greater than 50% longer to make a decision than the control group. The findings are suggestive that for some stimuli FDEs can discriminate between forgeries and disguises, and that this ability is due to a careful inspection and consideration of multiple features within a signature.     

论鉴定结论的质证

本文对鉴定结论质证的特殊内容、鉴定结论质证的主体以及鉴定结论质证中应注意的问题进行了分析，以探讨如何完善鉴定结论的质证。     

Understanding juror perceptions of forensic evidence: investigating the impact of case context on perceptions of forensic evidence strength

The most widely accepted model of juror decision making acknowledges the importance of both the case-specific information presented in the courtroom, as well as the prior general knowledge and beliefs held by each juror. The studies presented in this paper investigated whether mock jurors could differentiate between evidence of varying strengths in the absence of case information and then followed on to determine the influence that case context (and therefore the story model) has on judgments made about the strength of forensic DNA evidence. The results illustrated that mock jurors correctly identified various strengths of evidence when it was not presented with case information; however, the perceived strength of evidence was significantly inflated when presented in the context of a criminal case, particularly when the evidence was of a weak or ambiguous standard. These findings are discussed in relation to the story model, and the potential implications for real juries.     

Naturalistic decision making in forensic science: toward a better understanding of decision making by forensic team leaders

This study uses the naturalistic decision-making (NDM) perspective to examine how Dutch forensic team leaders (i.e., the officers in charge of criminal forensic research from the crime scene until the use of laboratory assistance) make decisions in real-life settings and identifies the contextual factors that might influence those decisions. First, a focus group interview was conducted to identify four NDM mechanisms in day-to-day forensic decision making. Second, a serious game was conducted to examine the influence of three of these contextual mechanisms. The results uncovered that forensic team leaders (i) were attracted to obtain further information when more information was initially made available, (ii) were likely to devote more attention to emotionally charged cases, and (iii) used not only forensic evidence in the decision making but also tactical, unverified information of the police inquiry. Interestingly, the measured contextual influences did not deviate significantly from a control group of laypeople.     

Comparison of GSR Composition Occurring at Different Locations Around the Firing Position

Abstract: Variations in gunshot residue (GSR) compositions are used in the reconstruction of shooting incidents. In this study, GSR samples taken from seven different locations around and in the firearm were collected and analyzed using scanning electron microscopy/energy dispersive X‐ray analysis. Four different types of ammunition were applied. Very low correlations were found when different ammunition were used. This clearly shows that it is possible to differentiate between ammunition types. When the same ammunition was used, high correlations were found between samples taken from external positions (such as hands of shooter, bullet‐entrance holes) but poor correlation was found between internal samples (such as firearm barrel, cartridge case) and external samples. A high degree of association was found between samples that simulated victim and shooter. These findings clearly demonstrate that GSR comparison studies are meaningful but care needs to be taken when choosing suitable exhibits. External samples (such as hands of shooter, bullet‐entrance holes) are more suitable candidates than internal samples (barrel of the firearm, cartridge case).     

Toolmark Identification of a Mattock to a Clod of Soil from a Grave

Abstract: At a recent bushland gravesite that contained a deceased male, a clod of soil displaying a striated toolmark was collected during the excavation of the grave. This clod was preserved, and the mark was cast using Mikrosil?. Shovels and a mattock, which had been discarded by the suspects, were subsequently found at another location. A toolmark comparison identified the hoe end of the mattock head as having produced the striated toolmark.     

《死刑案件证据规定》第23条的诠释与解读——以鉴定意见审查判断为视角

2010年7月1日《关于办理死刑案件审查判断证据若干问题的规定》已正式实施,该规定第23条明确规定了鉴定意见审查判断时应当着重考察的若干事项。鉴定意见作为现代诉讼活动中的“证据之王”,在案件事实认定中具有极为重要的地位,甚至在死刑案件中扮演着“一纸定生死”的角色。通过对《死刑案件证据规定））第23条的诠释与解读,进一步明确刑事案件,尤其是死刑案件中的鉴定意见证据能力及证明力,有助于切实保障案件裁判的司法公正、维护案件当事各方的合法权益。