When emotions get the better of us: the effect of contextual top-down processing on matching fingerprints

The effects of cognitive bias, examiner expertise, and stimulus material on forensic evidence analysis

Forensic examiners have come under scrutiny due to high-profile exonerations, highlighting the consequences that contextual bias can have on investigations. Researchers have proposed solutions to reduce the effects of bias including blind testing and redacting task-irrelevant information. Practitioners have concerns over the limitations of some of this research that uses untrained students to examine complex pieces of forensic evidence (e.g., fingerprints) (1; but see 2 for studies including trained experts and/or actual casework). This study sought to (a) examine the effect of contextual bias on examiners' evaluation of forensic evidence by varying the amount of pre-comparison information available to participants, (b) compare student and expert examiners' performance and their vulnerability to contextual bias, and (c) examine the effects of contextual bias on examiners' evaluation of different types of forensic evidence. Expert fingerprint examiners and student participants were presented with varying amounts of pre-comparison case information and compared matching and non-matching fingerprint and footwear impression evidence. Results suggest no effects of blinding examiners from case information or redacting task-irrelevant information. As expected, expert fingerprint examiners were more likely to correctly identify matching fingerprints and correctly exclude non-matching fingerprints than students. However, expert fingerprint examiners were no better than student participants at comparing footwear impression evidence. These findings suggest that sample, stimulus selection, and discipline-specific training matter when investigating bias in forensic decision making. These findings suggest caution when using forensic stimuli with student samples to investigate forensic decision-making and highlight the need for more research on redaction procedures.

A global survey of the attitudes and perspectives of cognitive bias in forensic anthropology

It is now well established that decision making can be susceptible to cognitive bias in a broad range of fields, with forensic science being no exception. Previously published research has revealed a bias blind spot in forensic science where examiners do not recognise bias within their own domain. A survey of 101 forensic anthropology practitioners (n = 52) and students (n = 38) was undertaken to assess their level of awareness of cognitive bias and investigate their attitudes towards cognitive bias within forensic anthropology. The results revealed that the forensic anthropology community (∼90%) had a high level of awareness of cognitive bias. Overall ∼89% expressed concerns about cognitive bias in the broad discipline of forensic science, their own domain of forensic anthropology, and in the evaluative judgments they made in reconstruction activities, identifying a significant reduction in the bias blind spot. However, more than half of the participants believed that bias can be reduced by sheer force of will, and there was a lack of consensus about implementing blinding procedures or context management. These findings highlight the need to investigate empirically the feasibility of proposed mitigating strategies within the workflow of forensic anthropologists and their capabilities for increasing the transparency in decision making.

Unpacking workplace stress and forensic expert decision-making: From theory to practice

Workplace stress can affect forensic experts' job satisfaction and performance, which holds financial and other implications for forensic service providers. Therefore, it is important to understand and manage workplace stress, but that is not simple or straightforward. This paper explores stress as a human factor that influences forensic expert decision-making. First, we identify and highlight three factors that mitigate decisions under stress conditions: nature of decision, individual differences, and context of decision. Second, we situate workplace stress in forensic science within the Challenge-Hindrance Stressor Framework. We argue that stressors in forensic science workplaces can have a positive or a negative impact, depending on the type, level, and context of stress. Developing an understanding of the stressors, their sources, and their possible impact can help forensic service providers and researchers to implement context-specific interventions to manage stress at work and optimize expert performance.

Science, evidence, law, and justice

For nearly 25 y, the Committee on Science, Technology, and Law (CSTL), of the National Academies of Sciences, Engineering, and Medicine, has brought together distinguished members of the science and law communities to stimulate discussions that would lead to a better understanding of the role of science in legal decisions and government policies and to a better understanding of the legal and regulatory frameworks that govern the conduct of science. Under the leadership of recent CSTL co-chairs David Baltimore and David Tatel, and CSTL director Anne-Marie Mazza, the committee has overseen many interdisciplinary discussions and workshops, such as the international summits on human genome editing and the science of implicit bias, and has delivered advisory consensus reports focusing on topics of broad societal importance, such as dual use research in the life sciences, voting systems, and advances in neural science research using organoids and chimeras. One of the most influential CSTL activities concerns the use of forensic evidence by law enforcement and the courts, with emphasis on the scientific validity of forensic methods and the role of forensic testimony in bringing about justice. As coeditors of this Special Feature, CSTL alumni Tom Albright and Jennifer Mnookin have recruited articles at the intersection of science and law that reveal an emerging scientific revolution of forensic practice, which we hope will engage a broad community of scientists, legal scholars, and members of the public with interest in science-based legal policy and justice reform.

Associations between emotions and psychophysiological states and confirmation bias in question formulation in ongoing simulated investigative interviews of child sexual abuse

Introduction

In forensic settings interviewers are advised to ask as many open-ended questions as possible. However, even experts may have difficulty following this advice potentially negatively impacting an investigation. Here, we sought to investigate how emotions and psychophysiological parameters are associated with question formulation in real time in an ongoing (simulated) child sexual abuse (CSA) interview.

Method

In a experimental study, psychology students (N = 60, Mage = 22.75) conducted two interviews with child avatars, while their emotions (anger, sadness, disgust, surprise and relief), GSR and heart rate (HR) were registered.

Results

First, we found that general emotionality related to CSA and perceived realness of the avatars was associated with stronger overall emotional reactions. Second, we found that closed (vs. open) questions were preceded by more facially observable anger, but not disgust, sadness, surprise or relief. Third, closed (vs. open) questions were preceded by higher GSR resistance and lower heart rate.

Discussion

Results suggest for the first time that emotions and psychophysiological states can drive confirmation bias in question formulation in real time in CSA.

The added value of behavioural information in crime scene investigations

Forensic and behavioural science are often seen as two different disciplines. However, there is a growing realization that the two disciplines should be more strongly integrated. Incorporating psychological theories on human behaviour in forensic science could help solving investigative problems, especially at the crime scene. At the crime scene it is not just about applying scientific methods to analyse traces; these traces must first be perceived and categorized as relevant. At the crime scene, the behavioural perspective of an investigative psychologist could play an important role. In this study, we examine to what extent (1) investigative psychologists detect deviant behavioural cues compared to forensic examiners when investigating a crime scene, (2) forensic examiners can find the relevant traces that can be associated with this behaviour and (3) the availability of a psychological report highlighting these behavioural cues helps forensic examiners in finding more relevant traces. To this end, a total of 14 investigative psychologists and 40 forensic examiners investigated a virtual 3D mock crime scene. The results of this study show that investigative psychologists see significantly more deviant behavioural cues than forensic examiners, and that forensic examiners who receive a psychological report on these cues recognize and collect significantly more traces that can be linked to deviant behaviour and have a high evidential value than examiners who did not receive this information. However, the study also demonstrates that behavioural information is likely to be ignored when it contradicts existing beliefs.

Verifying unfamiliar identities: Effects of processing name and face information in the same identity-matching task

Matching the identity of unfamiliar faces is important in applied identity verification tasks, for example when verifying photo ID at border crossings, in secure access areas, or when issuing identity credentials. In these settings, other biographical details-such as name or date of birth on an identity document-are also often compared to existing records, but the impact of these concurrent checks on decisions has not been examined. Here, we asked participants to sequentially compare name, then face information between an ID card and digital records to detect errors. Across four experiments (combined n = 274), despite being told that mismatches between written name pairs and face image pairs were independent, participants were more likely to say that face images matched when names also matched. Across all experiments, we found that this bias was unaffected by the image quality, suggesting that the source of the bias is somewhat independent of perceptual processes. In a final experiment, we show that this decisional bias was found only for name checks, but not when participants were asked to check ID card expiration dates or unrelated object names. We conclude that the bias arises from processing identity information and propose that it operates at the level of unfamiliar person identity representations. Results are interpreted in the context of theoretical models of face processing, and we discuss applied implications.

Cognitive and human factors in legal layperson decision making: Sources of bias in juror decision making

Juries in adversarial courts are tasked with several responsibilities. They are asked to: 1) assess the credibility and reliability of the evidence presented; 2) deliberate; 3) and then reach a decision. Jurors are expected to evaluate said evidence in a rational/impartial manner, thus allowing the defendant their right to a fair trial. However, psychological research has shown that jurors are not rational and can reach inaccurate decisions by being biased by certain factors. The aim of the current review was to explore the potential sources from which biases are introduced into the jury. Three main sources of bias were focussed upon: 1) pre-trial bias; 2) cognitive bias; 3) bias from external legal actors (expert witnesses). Legal scholars commonly cite deliberations as a method of attenuating individual juror bias, this claim is evaluated in the review. The review concludes that bias is a multifaceted phenomenon introduced from many different elements, and that several sources of bias may interact with one another during a jury trial to cause the effects of bias to snowball. Four recommendations are made: 1) juror selection should be utilised to create heterogenous juries that challenge problematic biases from individual jurors; 2) increase the quality of expert testimony through training; 3) procedures such as Linear Sequential Unmasking should be adopted by expert witnesses to filter out some sources of bias; 4) legal professionals and jurors should be educated about the effects that biases may have on decision making; 5) more research into bias in jurors is needed.

How time pressure and fingerprint complexity affect fingerprint examiner performance in an Eye Tracking Study

We conducted two experiments to examine the effects of time pressure and task difficulty on the strategies used and task accuracy during fingerprint examination. In Experiment I, we collected behavior and eye movement data from 31 fingerprint examiners in conditions with and without time pressure. In Experiment II, we used the same procedure but added a task difficulty variable. The results showed that, in contrast to the trials without time pressure, the fingerprint examiners used an observation mode with decreased fixation time and made fewer mistakes (stronger discriminability and higher response criterion) when under time pressure (Experiment I). This pattern was only observed when the task was less difficult. When the task was more difficult (Experiment II), the examiners tended to adopt an observation mode with more fixation counts, and time pressure weakened the accuracy of their performance. In conclusion, time pressure can influence decision-making by affecting the cognitive strategies used during fingerprint examination. And task difficulty has a moderating effect on the influence of time pressure.

Sports ingroup love does not make me like the sponsor's beverage but gets me buying it

Previous literature has shown that social identity influences consumer decision-making towards branded products. However, its influence on ones' own sensory perception of an ingroup (or outgroup) associated brand's product (i.e. sponsor) is seldom documented and little understood. Here, we investigate the impact of social identity (i.e. team identification) with a football team on the sensorial experience and willingness to buy a beverage, said to be sponsoring the ingroup or the outgroup team. Ninety subjects participated in one of three sensorial experience conditions (matched identity: ingroup beverage; mismatched identity: outgroup beverage; control: no group preference). Each participant tasted the new sponsoring beverage and answered a questionnaire about their subjective sensorial experience of the beverage. EEG and BVP were synchronously collected throughout. Analyses revealed that team identification does not influence subjective responses and only slightly modulates physiological signals. All participants reported high valence and arousal values while physiological signals consistently translated negative affects across groups, which showed that participants reported to be happy/excited about trying the beverage while their physiological signals showed that they were feeling sad/depressed/angry. Crucially, despite a similar sensorial experience, and similar socially desirable report of the subjective experience, only participants in the matched identity group demonstrate higher willingness to buy, showing that the level of team identification, but not taste or beverage quality, influences willingness to buy the said sponsor's product.

'Anyone who commits such a cruel crime, must be criminally irresponsible': context effects in forensic psychological assessment

In recent years, it has become clear that expert opinion can be biased. It has been argued that forensic psychologists may also be susceptible to bias. In the present study, the vulnerability of forensic psychological evaluation of the suspect's mental health to the context effect (i.e. the influencing of the expert opinion by irrelevant information) was tested. Master students in forensic psychology were asked to interpret test scores of a suspect in a fictitious double murder case. Some participants received a version of the case in which the description of the murders was neutral. Others received a more explicit version. Whereas the explicitness should not affect the forensic psychological evaluation, it was found that participants in the latter condition seemed more concerned about the suspect's mental health than those in the former. It is concluded that training programmes in forensic psychological assessment should devote attention to bias.

Bodily Information and Top-Down Affective Priming Jointly Affect the Processing of Fearful Faces

According to embodied theories, the processing of emotions such as happiness or fear is grounded in emotion-specific perceptual, bodily, and physiological processes. Under these views, perceiving an emotional stimulus (e.g., a fearful face) re-enacts interoceptive and bodily states congruent with that emotion (e.g., increases heart rate); and in turn, interoceptive and bodily changes (e.g., increases of heart rate) influence the processing of congruent emotional content. A previous study by Pezzulo et al. (2018) provided evidence for this embodied congruence, reporting that experimentally increasing heart rate with physical exercise facilitated the processing of facial expressions congruent with that interoception (fear), but not those conveying incongruent states (disgust or neutrality). Here, we investigated whether the above (bottom-up) interoceptive manipulation and the (top-down) priming of affective content may jointly influence the processing of happy and fearful faces. The fact that happiness and fear are both associated with high heart rate but have different (positive and negative) valence permits testing the hypothesis that their processing might be facilitated by the same interoceptive manipulation (the increase of heart rate) but two opposite (positive and negative) affective primes. To test this hypothesis, we asked participants to perform a gender-categorization task of happy, fearful, and neutral faces, which were preceded by positive, negative, and neutral primes. Participants performed the same task in two sessions (after rest, with normal heart rate, or exercise, with faster heart rate) and we recorded their response times and mouse movements during the choices. We replicated the finding that when participants were in the exercise condition, they processed fearful faces faster than when they were in the rest condition. However, we did not find the same reduction in response time for happy (or neutral) faces. Furthermore, we found that when participants were in the exercise condition, they processed fearful faces faster in the presence of negative compared to positive or neutral primes; but we found no equivalent facilitation of positive (or neutral) primes during the processing of happy (or neutral) faces. While the asymmetries between the processing of fearful and happy faces require further investigation, our findings promisingly indicate that the processing of fearful faces is jointly influenced by both bottom-up interoceptive states and top-down affective primes that are congruent with the emotion.

The distinction between discriminability and reliability in forensic science

Forensic science plays an increasingly important role in the criminal justice system; yet, many forensic procedures have not been subject to the empirical scrutiny that is expected in other scientific disciplines. Over the past two decades, the scientific community has done well to bridge the gap, but have likely only scratched the tip of the iceberg. We offer the discriminability-reliability distinction as a critical framework to guide future research on diagnostic-testing procedures in the forensic science domain. We argue that the primary concern of the scientist ought to be maximizing discriminability and that the primary concern of the criminal justice system ought to be assessing the reliability of evidence. We argue that Receiver Operating Characteristic (ROC) analysis is uniquely equipped for determining which of two procedures or conditions has better discriminability and we also demonstrate how estimates of reliability can be extracted from this Signal Detection framework.

Integrating explicit contextual priors and kinematic information during anticipation

We examined the interaction between explicit contextual priors and kinematic information during anticipation in soccer. We employed a video-based anticipation task where skilled soccer players had to predict the direction of the imminent actions of an attacking opponent in possession of the ball. The players performed the task both with and without explicit contextual priors pertaining to the opponent's action tendencies. The strength of the opponent's action tendencies was altered in order to manipulate the reliability of contextual priors (low vs. high). Moreover, the reliability of kinematic information (low vs. high) was manipulated using the temporal occlusion paradigm. The explicit provision of contextual priors biased anticipation towards the most likely direction, given the opponent's action tendencies, and resulted in enhanced performance. This effect was greater under conditions where the reliability of kinematic information was low rather than high. When the reliability of kinematic information was high, the players used explicit contextual priors of high, but not low, reliability to inform their judgements. Findings suggest that athletes employ reliability-based strategies when integrating contextual priors with kinematic information during anticipation. The impact of explicit contextual priors is dependent on the reliability both of the priors and the evolving kinematic information.

Latent print comparison and examiner conclusions: A field analysis of case processing in one crime laboratory

Scholarship on the latent print comparison process has expanded in recent years, responsive to the call for rigorous research by scholarly groups (e.g., National Academy of Sciences, 2009; President's Council of Advisors on Science and Technology, 2016). Important to the task of ultimately improving accuracy, consistency, and efficiency in the field is understanding different workflows and case outcomes. The current study describes the casework completed by a latent print unit in a large laboratory during one calendar year (2018), including a unique workflow that involves Preliminary AFIS Associations reported out as investigative leads. Approximately 45% of all examined prints were deemed to be of sufficient quality to enter into AFIS, and 22% of AFIS entries resulted in potential identifications. But examiner conclusions and AFIS outcomes (across three AFIS databases) varied according to case details, print source, and AFIS database. Moreover, examiners differed in case processing, sufficiency determinations, and AFIS conclusions. Results are discussed with respect to implications for future research (e.g., comparing these data to case processing data for other laboratories) and ultimately improving the practice of latent print examination.

Organizational and Human Factors Affecting Forensic Decision-Making: Workplace Stress and Feedback

Although forensic examiners operate in a stressful environment, there is a lack of understanding about workplace stress and feedback. These organizational and human factors can potentially impact forensic science judgments. In this study, 150 practicing forensic examiners from one laboratory were surveyed about their experiences of workplace stress, and the explicit and implicit feedback they receive. Forensic examiners reported that their high stress levels originated more from workplace-related factors (management and/or supervision, backlogs, and the pressure to do many cases) than from personal related factors (family, medical, and/or financial). The findings showed that a few (8%) of the forensic examiners sometimes felt strong implicit feedback about what conclusions were expected from them and that some (14%) also strongly felt that they were more appreciated when they helped to solve a case (e.g., by reaching a "match" as opposed to an "inconclusive" conclusion). Differences were found when comparing workplace stress and feedback levels across three core forensic science fields (forensic biology, chemistry, and latent prints) and across career stages (early, mid, and late). Gaining insights into the stress factors within a workplace and explicit and implicit feedback has implications for developing policies to improve the well-being, motivation, and performance of forensic examiners.

Quality of Laypersons' Assessment of Forensically Relevant Stimuli

The current study examined the potential for cognitive bias in lay examiners' comparisons of footwear impressions within the technical review process while addressing limitations of previous research. Prior research has found inconsistent results regarding the extent to which cognitive bias may influence forensic comparisons, often asking non-experts to review forensic stimuli above their competency level. Furthermore, past research has largely ignored the potential for cognitive bias during the technical review process. In collaboration with the Miami-Dade Police Department's Forensic Services Bureau, we examined the effects of previous examiners' level of experience and prior knowledge of the previous examiner's decision on the technical review stage of footwear impression stimuli. Before lay examiners were presented with pairs of known match and nonmatch footwear impressions, they were either told that an expert or a novice had previously examined them and determined them to be either a match, nonmatch, or inconclusive (plus a no-information condition). Participants then evaluated each pair of footwear impressions to make their own determinations of match, nonmatch, or inconclusive. Results support the technical review process for all decision types, as known nonmatch stimuli were generally more difficult for lay examiners to assess than known match stimuli. Knowledge of a prior examiner's decision and status was observed only when the prior decision was inconclusive, suggesting the need for inclusion of inconclusive decisions in future research examining cognitive bias in forensic examination.

Practical Solutions to Forensic Contextual Bias

Abstract. In 2009, the National Research Council (NRC) globally criticized forensic science and, in particular, the potential for contextual bias to increase errors in forensic examination. Nevertheless, very few research-based solutions have been proposed and, of the current recommendations, none are consistently used in practice. Two experiments are presented here. Experiment 1 replicates and extends the Quigley-McBride and Wells (2018) study in which fingerprint lineups (the Filler-Control Procedure) were shown to neutralize the effect of contextual information on novice fingerprint evaluations. Experiment 2 demonstrates that restricting the use of evidence lineups to verification decisions would also be effective for reducing incorrect match decisions without straining resources. In both experiments, the filler-control procedure consistently reduced the effect of suggestive contextual information and protected innocent suspect prints from being mistakenly matched to crime samples. Interdisciplinary approaches are discussed as a way to help close the gap between research and forensic science practice.

A risk-based approach to cognitive bias in forensic science

Over the past decade, the potential impact of cognitive bias in forensic science has instigated much discussion and debate between academics, scientists and those in the justice sector. Evidence of bias influencing subjective decision-making across a range of forensic disciplines has been described in the literature. Forensic service organisations are being urged to address cognitive bias in subjective decision-making by designing processes or procedures to limit access to (irrelevant) contextual information or reduce dependence on cognitive functions. Although some laboratories have implemented bias mitigating strategies, with varying impact on operational efficiency, there has been no systematic assessment of the risk posed by cognitive bias. Forensic Science SA assessed the potential impact of bias on forensic interpretations across multiple disciplines, using a risk management framework. This process proved useful in assessing the effectiveness of existing bias mitigating strategies and identified the latent level of risk posed. While all forensic organisations should seek to implement bias limiting measures that are simple, cost-effective and do not adversely impact efficiency, using a risk-based approach has contextualised the limited benefit of introducing resource hungry measures, as postulated in the literature. That is not to suggest that forensic organisations should dismiss the potential influence of cognitive bias but they need to strike an appropriate balance between risk and return, as they do with any business risk.

The science behind Bayley v The Queen (2016)

Eyewitness identification was the principal evidence in DPP v Bayley (2015), wherein Adrian Bayley was convicted of raping and assaulting a woman in 2000. Twelve years after the attack, the victim identified Bayley from a photograph on Facebook and later in a formal police identification procedure. At the time of the initial Facebook identification, the victim knew about Bayley's involvement in Gillian Meagher's case. Bayley successfully appealed his conviction in 2016. The court of appeal held that the identification evidence had multiple weaknesses and should not have been permitted at the initial trial. In their decision, the court relied on legal precedents to support their judgement. This article reviews the empirical evidence regarding each of the issues raised by the court and how the stressfulness of an event can influence the reliability of an identification, and speculates about why the jury rendered a guilty verdict based on weak identification evidence.

Blinding or information control in diagnosis: could it reduce errors in clinical decision-making?

Background Clinical medicine has long recognized the potential for cognitive bias in the development of new treatments, and in response developed a tradition of blinding both clinicians and patients to address this specific concern. Although cognitive biases have been shown to exist which impact the accuracy of clinical diagnosis, blinding the diagnostician to potentially misleading information has received little attention as a possible solution. Recently, within the forensic sciences, the control of contextual information (i.e. information apart from the objective test results) has been studied as a technique to reduce errors. We consider the applicability of this technique to clinical medicine. Content This article briefly describes the empirical research examining cognitive biases arising from context which impact clinical diagnosis. We then review the recent awakening of forensic sciences to the serious effects of misleading information. Comparing the approaches, we discuss whether blinding to contextual information might (and in what circumstances) reduce clinical errors. Summary and outlook Substantial research indicates contextual information plays a significant role in diagnostic error and conclusions across several medical specialties. The forensic sciences may provide a useful model for the control of potentially misleading information in diagnosis. A conceptual analog of the forensic blinding process (the "agnostic" first reading) may be applicable to diagnostic investigations such as imaging, microscopic tissue examinations and waveform recognition. An "agnostic" approach, where the first reading occurs with minimal clinical referral information, but is followed by incorporation of the clinical history and reinterpretation, has the potential to reduce errors.

Fingerprint identification: advances since the 2009 National Research Council report

This paper will discuss the major developments in the area of fingerprint identification that followed the publication of the National Research Council (NRC, of the US National Academies of Sciences) report in 2009 entitled: Strengthening Forensic Science in the United States: A Path Forward. The report portrayed an image of a field of expertise used for decades without the necessary scientific research-based underpinning. The advances since the report and the needs in selected areas of fingerprinting will be detailed. It includes the measurement of the accuracy, reliability, repeatability and reproducibility of the conclusions offered by fingerprint experts. The paper will also pay attention to the development of statistical models allowing assessment of fingerprint comparisons. As a corollary of these developments, the next challenge is to reconcile a traditional practice dominated by deterministic conclusions with the probabilistic logic of any statistical model. There is a call for greater candour and fingerprint experts will need to communicate differently on the strengths and limitations of their findings. Their testimony will have to go beyond the blunt assertion of the uniqueness of fingerprints or the opinion delivered ispe dixit.

Discrepancies in expert decision-making in forensic fingerprint examination

The purpose of the present study was to analyse professional fingerprint examiners' investigative practices in the context of discrepancy decisions concerning challenging latents during fingerprint analysis and identification. The participants were fingerprint experts from the Forensic Laboratory of the Finnish National Bureau of Investigation. The data were from five audio-recorded "discrepancy meetings" where two examiners were discussing the rationale and justification for their differing interpretations of challenging and distorted fingerprint evidence. The meetings were chaired by the quality manager of the fingerprint group, who also in the first author of this article. The research questions addressed were as follows: What does the examiner see in the latent fingerprints? What does the examiner actively do with the latents? How were decisions made during the investigative process? In accordance with Goodwin's professional vision framework, the results revealed how the participants used partial and limited information in making judgments about the difficult and distorted latents. The examiners appeared to be involved in active, constructive efforts, mentally, to repair poor latents by supplementing with missing information. They also highlighted various aspects of latents by colour coding as well as manipulated fingerprint images in several ways so as to make the significant patterns easier to recognize. Because the methods and practices of characterizing latents were only vaguely specified, the examiners used locally developed ad hoc practices to facilitate their investigations, ending up with different interpretations. It is concluded in the article that the fingerprint community in Finland should make strong efforts to develop the methods of fingerprint investigation and determine clearer criteria for decision making and documentation practices. Furthermore, the interpretations made by fingerprint experts should be made more transparent to the customers.

Latent Fingerprint Matching: Performance Gain via Feedback from Exemplar Prints

Latent fingerprints serve as an important source of forensic evidence in a court of law. Automatic matching of latent fingerprints to rolled/plain (exemplar) fingerprints with high accuracy is quite vital for such applications. However, latent impressions are typically of poor quality with complex background noise which makes feature extraction and matching of latents a significantly challenging problem. We propose incorporating top-down information or feedback from an exemplar to refine the features extracted from a latent for improving latent matching accuracy. The refined latent features (e.g. ridge orientation and frequency), after feedback, are used to re-match the latent to the top K candidate exemplars returned by the baseline matcher and resort the candidate list. The contributions of this research include: (i) devising systemic ways to use information in exemplars for latent feature refinement, (ii) developing a feedback paradigm which can be wrapped around any latent matcher for improving its matching performance, and (iii) determining when feedback is actually necessary to improve latent matching accuracy. Experimental results show that integrating the proposed feedback paradigm with a state-of-the-art latent matcher improves its identification accuracy by 0.5-3.5 percent for NIST SD27 and WVU latent databases against a background database of 100k exemplars.

Expertise in crime scene examination: comparing search strategies of expert and novice crime scene examiners in simulated crime scenes

OBJECTIVE

The strategies of novice and expert crime scene examiners were compared in searching crime scenes.

BACKGROUND

Previous studies have demonstrated that experts frame a scene through reconstructing the likely actions of a criminal and use contextual cues to develop hypotheses that guide subsequent search for evidence.

METHOD

Novice (first-year undergraduate students of forensic sciences) and expert (experienced crime scene examiners) examined two "simulated" crime scenes. Performance was captured through a combination of concurrent verbal protocol and own-point recording, using head-mounted cameras.

RESULTS

Although both groups paid attention to the likely modus operandi of the perpetrator (in terms of possible actions taken), the novices paid more attention to individual objects, whereas the experts paid more attention to objects with "evidential value." Novices explore the scene in terms of the objects that it contains, whereas experts consider the evidence analysis that can be performed as a consequence of the examination.

CONCLUSION

The suggestion is that the novices are putting effort into detailing the scene in terms of its features, whereas the experts are putting effort into the likely actions that can be performed as a consequence of the examination.

APPLICATION

The findings have helped in developing the expertise of novice crime scene examiners and approaches to training of expertise within this population.