Cognitive Bias in Expert Testimony

Introduction

Expert evidence is an important part of the criminal justice system as it is needed for administering justice in cases where expert evidence gives support to the arguments being put forth in the court. However, expert evidence may not always be reliable in leading to just and fair consequences in the courts of law because such evidence may be vitiated by bias (Dror, McCormack, & Epstein, 2015). There is sufficient research to lend credence to the fact that expert evidence may be prompted by cognitive bias, for which then it becomes necessary to understand how such biases can impact expert testimony and how expert evidence may be influenced by contextual information and cognitive bias. In recent times, cognitive psychology and science has tried to provide insight into how cognitive bias is created and how potential weaknesses can vitiate evidence by experts (Dror, McCormack, & Epstein, 2015; Haselton, Nettle, & Murray, 2015). It is important to collate this information in light of the important task that the experts perform in courts of law as witnesses so that means or methods of mitigating the effects of cognitive bias on expert evidence can be devised. It is also important because there is now an increased dependence on forensic evidence in the criminal justice system and a generally accepted notion that forensic evidence is quite reliable whereas evidence shows that even forensic evidence can be misinterpreted, or unreliable or the decision should not have been based on the hypotheses drawn by the forensic experts (Smita, Morgana, & Lagnado, 2018). On the other hand, there is significant involvement of experts in forensic evidence in Handwriting comparison, Fingerprint evidence, DNA evidence, Ballistic (bullet) comparison, and Analysis of hair and fibres. The likelihood of bias even in scientifically driven settings is high when interpretation of the evidence is based on subjective determination of the experts who are likely to be impacted by contextual information as well as confirmation biases that leads them to seek information that confirms existing biases as well as the determination of the experts to catch the perpetrators of the crimes. An illusion of corroboration may be created when the experts use confirmation bias to create a case for the hypothesis (Nakhaeizadeh, Dror, & Morgan, 2014). Cognitive science has suggested that expert cognitive bias can be seen in the most dedicated and committed experts as well and that such bias can have undesirable results for the criminal justice system can be assumed for the purposes of this dissertation. One research points out that expert cognitive bias can occur even without the expert realising it like where “experts' conclusions on whether crime scene evidence was left by a specific person were influenced by whether they were told that the suspect confessed or, alternatively, that the suspect probably did not commit the crime because he has an alibi” (Dror, McCormack, & Epstein, 2015, p. 8). Research in this area is significant because not only is it important to understand why and how cognitive bias occurs, it is also important to find ways to improve the quality of the contribution that experts make to the fact-finding process within the criminal justice system. Given the important role that experts play in guiding juries and judges to decision making in criminal cases, it becomes important and critical to improve the process by which such expert evidence is taken so that the possibility of expert bias is also addressed within the criminal justice system and cognitive science is used to help devise ways to mitigate the impacts of such bias (Dror, McCormack, & Epstein, 2015). An early research on cognitive bias and criminal justice system did try to arrive at recommendations to improve the system so that effect of bias can be mitigated (Eskridge Jr & Ferejohn, 2001). An important point made in this research is on the link between public theory and cognitive psychology, which is also relevant to this research as it is trying to link the two through an analysis of the expert witnesses’ cognitive bias, in this context, it is said that:

The most interesting issues of public law (for us) are those relating to institutional design and function. When thinking about statutory interpretation, judicial review, and legislative and administrative procedures, it is useful to have a theory about how the governmental system works in our regulatory state, how it breaks down, and how it leads to decisions that do not serve the public interest. Hence, theories of regulatory pathology are useful. Within the academy, public choice theory has been particularly popular: selfish interest groups and public officials highjack the governmental process for their private gain, thereby undermining the public interest in efficient rules and distributions. The main regulatory pathology for public choice theory is rent-seeking, the private plunder of the public fiscal. Republican theory offers a less cynical point of view. It maintains that politics is the forum where collective problems are resolved and values are advanced. The main regulatory pathology for republican theory is breakdowns in the deliberative process. Theories of cognitive psychology are highly relevant to both these schools of thought, because these theories are informed judgments about how even the most well-motivated human decisionmakers make mistakes” (Eskridge Jr & Ferejohn, 2001, p. 616).

Proceeding on the same premise as the one discussed above, this dissertation seeks to link the research on cognitive bias in cognitive psychology field with the public law theory in an effort to collate the two for arriving at solutions to the problem of cognitive bias in expert testimony so as to improve the quality of the criminal justice system and its outcomes. Cognitive bias is a significant topic in public law research on criminal justice system because such biases do tend to influence the reasoning of experts when they are presenting their evidence with relevance to a number of aspects in the criminal justice system, including but not limited to identifying suspects, evaluating evidence, evaluating alibis, evaluating forensic evidence, and other such aspects that may be compromised through incomplete information or unreasoned decisions (The Parliamentary Office of Science and Technology, 2015). As such, cognitive bias is a relevant topic for criminal justice system because there is now increasing evidence on how biased reasoning and unfair judgement are compromising the quality of the decisions of the courts (The Parliamentary Office of Science and Technology, 2015). The Criminal Procedure Rules have also taken into consideration the possibility of expert bias and addressed it in part 19.2 by emphasising on the expert’s duty to the court, which includes giving objective and unbiased opinions that are within the expert’s area or areas of expertise. It is also noted in the Rules that the duty of the expert to the court overrides any obligation to the person from whom the expert receives instructions or by whom the expert is paid. This is to mitigate the effects of role effects bias which can cloud the judgement of the expert by subconsciously influencing him to interpret evidence that supports the side that he identifies with in the adversarial case, which could be prosecutor or the defence. The significance of use of cognitive psychology for understanding the nature of cognitive bias within the criminal justice system can be argued for because the biases are generally the result of cognitive processes like assumptions, stereotypes and contextual information, which have an impact on the legal process of the criminal justice system where the cognitive biases are capable of influencing judgement unintentionally. The affective impacts of cognitive bias is reported with reference to decisions of forensic experts, witnesses and mock jurors (The Parliamentary Office of Science and Technology, 2015). Cognitive psychology can help to assess the ways in which cognitive bias affects the evidence of experts presented within the criminal justice system as most people may be unaware of their cognitive biases and may not be able to control the effect of such biases, which can be made clear by the cognitive psychology. Cognitive psychology can also be useful in mitigating the effects of such cognitive bias through targeted strategies. The value of cognitive psychology in improving this aspect of the public law system is not recognised by judiciary as well because there are proposals for training judges so as to reduce the influence of cognitive biases in court and there is also a proposal by the President of the Supreme Court for improved access for researchers to study biases in the justice system so that the criminal justice system can improve in this context (The Parliamentary Office of Science and Technology, 2015). The UK government too recognises the need for responding to cognitive bias but rues the fact that not enough research has been done so far to understand the scope of the problem of unreliable evidence, which supports the need for research studies like the present one; the government says:

“It recognises the potential value of the proposed reliability test in reducing the risk of unsafe convictions arising from unreliable expert evidence. However, there is no robust estimate of the size of the problem to be tackled – either in terms of the number of cases where unreliable expert evidence is adduced, nor in the impact this has in terms of subsequently quashed convictions” (UK Ministry of Justice, 2013).

The greater focus of this dissertation is on cognitive psychology research as this is useful to pointing at the reasons for cognitive bias and also recommending ways for mitigating the effects of the bias, which can be applied to mitigating the impacts of cognitive bias on the outcomes of the criminal justice system.

Cognitive bias: Nature and implications

Cognition is a mental process that involves knowledge, awareness, perception, reasoning and judgement (Forensic Science Regulator, 2015, p. 10). As such, it is distinct from emotion and volition. Cognitive bias is related to cognition. As defined by the by the PCAST report in 2016 cognitive bias includes “contextual bias, where individuals are influenced by irrelevant background information; confirmation bias, where individuals interpret information, or look for new evidence, in a way that conforms to their pre-existing beliefs; and avoidance of cognitive dissonance where individuals are reluctant to accept new information that is inconsistent with their tentative conclusion” (PCAST Forensic Science Report, 2016). Cognitive bias then is a state which indicates a difference between objective reality and the subjective thought process of the individual in whom such bias is noted or as PCAST Forensic Science Report (2016) notes a ‘cognitive dissonance’. Another definition confirms this notion where it is written that cognitive bias relates to “cases in which human cognition reliably produces representations that are systematically distorted compared to some aspect of objective reality” (Haselton, Nettle, & Murray, 2015, p. 968). Another definition of cognitive bias is that it is a “pattern of deviation in judgement whereby inferences about other people and situations may be drawn in an illogical fashion” (Forensic Science Regulator, 2015, p. 10). In other words, there is a distinction between reality and the appreciation of the reality by the individual receiving the information where such distinction produces results that are contrary to what is represented in the reality. The important point is that there is something in the mind of the individual that leads to the disjunction between reality and the biased opinion. Psychology seeks to explain this disjunction and these explanations can help us to understand how such bias is created and how its effects within the criminal justice system can be mitigated. It is important to note at the outset that most people tend to display bias in judgements made in everyday life as this is “a natural element of the human psyche” (Forensic Science Regulator, 2015, p. 10). Such biases may be the results of people jumping to conclusions in an unreasonable manner or having a narrow or tunnel vision where they only see what they already expected or wanted, or being influenced by others; therefore, there are different reasons or ways in which people in general arrive at cognitively biased judgements (Forensic Science Regulator, 2015). When such biases become part of the criminal justice system however, it is problematic because these biases impact the decision making of the courts. Nevertheless, these biases may be a common feature even of the criminal justice system, especially in forensic science, because many processes in forensic science do require subjective evaluations and interpretations by the experts (Forensic Science Regulator, 2015). The courts also have an important and difficult task for explaining the admittance of certain kind of evidence when there may be some concerns about whether the interpretation of such evidence suffers from cognitive bias. An example can be seen in the case of R. v Rogers, in which the Court of Appeal (Criminal Division) was required to assess the admissibility of the evidence of the police officer’s identification of the accused from photographs where it was concerned that the identification was after the police officer was informed that there was a DNA match with the accused (R. v Rogers [2013] EWCA Crim. 2406 , 2013). The court held that such prior information of DNA match before the identification of the accused did not render the trial unfair or conviction unsafe (R. v Rogers [2013] EWCA Crim. 2406 , 2013). This seems to be an acceptance by the court that every instance of expert evidence cannot be subjected to the allegations of cognitive bias. The court however did note that while exposure to information about a prior DNA match does not automatically result in a biased decision by the expert, it can definitely at times influence such decisions and be guarded against (R. v Rogers [2013] EWCA Crim. 2406 , 2013). Therefore, the court does have a fine balancing act to do because cognitive biases are often times not guided by any intentional bias of the expert but may be driven by underlying and subconcious factors. Within evolutionary psychology, cognitive bias is explained as a ‘design flaw’ so that there are some explanations of cognitive bias based on the evolutionary reasons for the flaws. Three kinds of evolutionary reasons are identified as heuristics, where the selection of bias may favour some shortcuts that may work in some situations and not work in others; artifacts or apparent biases that can arise if the task at hand is not one for which the mind is designed; and error management biases that can arise where biased response patterns to adaptive problems resulted in lower error costs than unbiased response patterns (Haselton, Nettle, & Murray, 2015). Heuristics is the most common explanation of evolutionary flaws because it is necessitated by the processing limitations of human beings; because humans are limited in their ability to process information in short time, they will use shortcuts or rules of thumb, which may work at times and not work at others (Haselton, Nettle, & Murray, 2015). When the shortcuts do not work, bias or discrepancy in objective fact and cognitive representation occurs which can be attributed to evolutionary reasons. The biases of the error management kind however are genuine biases that are not results of any shortcuts but are of the nature that they themselves serve evolved functions (Haselton, Nettle, & Murray, 2015). These kind of biases are also more likely to impact expert evidence because these are not based on the latent inability of the expert to do his job thereby taking shortcuts like in the case of biases related to heuristics, but are “pertaining to judgments of threat, biases pertaining to evaluations of interpersonal relationships, and biases pertaining to evaluations of the self” (Haselton, Nettle, & Murray, 2015, p. 973). These may be related to the aversions that the expert may have to certain things, persons, groups or situations. These biases may also be related to perceptions of the intentions or dispositions of others (Haselton, Nettle, & Murray, 2015, p. 977).

In research on cognitive bias, it has been noted that bias is related to the indicator of affective state (Harding, Paul, & Mendl, 2004). Therefore, bias can indicate the affective state of the individual. There are many common types of cognitive bias. Anchoring bias happens when expert is relying on one piece of information, usually the initial piece of information learnt, in order to make a decision. As Twersky and Khaneman explained in 1974, "people make estimates by starting from an initial value that is adjusted to yield the final answer. The initial value, or starting point, may be suggested by the formulation of the problem, or it may be the result of a partial computation. In either case, adjustments are typically insufficient. That is, different starting points yield different estimates, which are biased toward the initial values.” Bias blind spot describes the situation where the person feels they are less biased than other people and finding it very difficult to identify their own bias. Confirmation bias takes place when people seek, weigh or interpret information in a manner that confirms their pre-existing beliefs or assumptions (Nickerson, 1998). In other words, information itself is secured for the purpose of confirming previous beliefs and assumptions. Another kind of bias is role effects, which is related to the bias that occurs where experts identify themselves within adversarial judicial systems as part of either the prosecution or defence teams; this identification with a side in the case leads to the introduction of a subconscious bias that can influence decisions in situations where the findings are ambiguous (Forensic Science Regulator, 2015). An example can be seen in the cases of fibre examinations of the potential contact between two textile items; where no matching fibres are found, cognitive bias may persuade an expert identifying himself with the prosecution side to interpret the findings as neutral and not as a situation where no contact occurred (Forensic Science Regulator, 2015). Role effects is not the same as motivational bias, which is driven by a favoured conclusion and support for ambiguous findings that lead to the favoured conclusion. This is described later in this section. Contextual bias occurs when information about the context of an event is presented and influences reasoning but is irrelevant to the decision and therefore, its use for decision making is not relevant and leads to wrong decisions. For example, the presence of contextual information can influence the results of forensic fingerprint identification (Dror I. , 2006). Unintentional stereotype bias can occur when people associate certain traits with their perception of social groups that the individuals regarding whom judgments are being made belong to, such as race, gender or age (Plant & Peruche, 2005). Experts may not even be aware of the fact that they have prejudices and that these associations between persons and their groups can influence decisions and behaviour (Plant & Peruche, 2005). In a research that confirms such stereotype bias in the police forces was conducted with video-game simulation in the US with researchers finding that police officers tended to shoot unarmed black suspects at a higher rate than unarmed white suspects; this is also called as a weapons bias (Plant & Peruche, 2005). Motivational bias occurs where the decision maker already has a favoured conclusion and this leads to a motivational influence on decision making when information consistent with a favoured conclusion is found and this is subjected to a lower level of scrutiny than the decision maker would have subjected information did not support the favoured outcome (Forensic Science Regulator, 2015). Expectation or experimenter bias occurs when the experimenter has pre-existing expectation of what will be found, and this affects what is actually found. This happens when the results or findings are ambiguous in nature and the experimenter can then interpret the results according to what he already expected thus filling the ambiguity with his own pre conceived notions of what should be expected (Forensic Science Regulator, 2015). Such expectation bias can see the experimenter disbelieve or downgrade the significance of actual findings because these conflict with their original expectations or believe and certify material that supports pre-existing expectations (Forensic Science Regulator, 2015). Unintentional stereotype bias is one of the most common type of biases that are seen in the criminal justice system by experts (Greenwald, 2009). Experts are also susceptible to this kind of bias as they may also unintentionally attribute stereotypical traits to individuals from particular social groups and allow this to impact their decision making (Greenwald, 2009). The Implicit Association Test has been developed to help researchers assess how unintentional biases correlate with real-world discriminatory behaviour of the experts; and such research studies have found that even unintentionally, prejudicial notions about the members of a particular social group can have an impact on expert evidence because such evidence is interpreted by the experts on mistaken assumptions and therefore does not match objective reality (Greenwald, 2009). It is important note that unintentional cognitive biases are not the same as explicit prejudice so that experts may not even be aware that they have such biases and that they are being impacted in their decision making and for that reason they are not able to directly control the influence of such biases on their decision making (Greenwald, 2009). This is an important reason why strategies for countering intentional bias and explicit prejudice do not work to mitigate the effect of unintentional social bias and why targeted strategies are required to counter the effect of unintentional social biases and their effect on behaviour (Greenwald, 2009).

An example of stereotypical bias in the UK criminal justice system is related to the victims of rape, which is one of the offences where there is a gross difference between the reporting of rape cases and actual convictions (Ministry of Justice, Home Office and Office for National Statistics, 2013). Research shows that stereotypical beliefs about rape of women influence decisions even when these decisions may not be supported by the evidence presented (Ministry of Justice, Home Office and Office for National Statistics, 2013). Therefore, lack of signs of physical injury on the rape victim may be influential for leading to not guilty verdicts even though rape is not necessarily accompanied by evidence of physical force (Ministry of Justice, Home Office and Office for National Statistics, 2013). There is also evidence that if the victim does not exhibit emotional response then that could lead to not guilty verdicts (Ministry of Justice, Home Office and Office for National Statistics, 2013). Cognitive bias can influence the preparation, presentation and perception of expert evidence as will be discussed in the next part of this section. The risk of bias is shaped by a number of factors. Risk is lower when results are clear and unambiguous but, it is greater when results are increasingly dependent on subjective opinion of the expert. Risk is lower when the methodical approach used is one which has defined standards built on tested and validated principles but it is greater when the approach is ad hoc and personal to the expert. Risk is lower when experts are experienced and continuously meet acceptable standards of competence but greater when they are left to adopt their own approach. Finally, risk is lower when expert interpretation is subject to the scrutiny of competent peers and higher when such peer checking is less rigorous or conducted collaboratively (Forensic Science Regulator, 2015).

Cognitive bias in the court rooms

Expert evidence plays an important role in the decision making in the courts. Research on cognitive bias in the courtrooms has demonstrated how cognitive bias can lead to wrong decisions in the courts (Smita, Morgana, & Lagnado, 2018). It is emphasised that evidence presented by the experts to the courts can be misleading because evidence of experts is generally in the nature of hypotheses and such hypotheses may not be fully understood or presented (Smita, Morgana, & Lagnado, 2018). Expert evidence of this nature is unreliable evidence. This is also relevant to forensic evidence, which usually commands credibility but is also susceptible to expert cognitive bias in both the formulating of the hypothesis as well as interpreting of the evidence that links to the hypotheses; this is explained as follows:

“When forensic evidence is used throughout a criminal investigation, it is assumed to have some relation to the criminal act, and therefore has some ability to support the reconstruction of related events. More specifically, analysing an item of evidence aims to determine the value of parameters of this observed evidence (e.g. the refractive index of glass) which can subsequently be used in the interpretation stage to express a belief in hypotheses (e.g. possible sources). Therefore, variation may exist between the true and observed parameter value, impacting subsequent interpretations. Such variation depends upon the method's accuracy or systematic error (determined by the specificity (true negative rate) and sensitivity (true positive rate), together with a threshold above which the method can be called ‘reliable’, as well as on information on its precision or random error (their repeatability and reproducibility). In addition, factors may in- fluence parameter values post-event, such as environmental conditions and collection strategies. ‘Unreliable expert evidence’ then relates to the extent to which the meaning of the uncertainty caused by such factors are and can be considered in the interpretation and presentation stages of the forensic science process” (Smita, Morgana, & Lagnado, 2018, pp. 128-129).

Unpacking what has been said above, some important points may be made out about cognitive bias in forensic expert evidence. The first point is that forensic evidence though interpreted through methods, there may be variation in the interpretation of the evidence based on the systematic error, sensitivity, information on precision or random error, environmental conditions and collection strategies, and finally the “Unreliable expert evidence relates to the extent to which the meaning of the uncertainty caused by such factors are and can be considered in the interpretation and presentation stages of the forensic science process.” While these are instances of objective bias, there are also evidence interpretation where subjective bias comes into play; this is relevant to expert evidence on handwriting analysis and the analysis of skeletal remains (Smita, Morgana, & Lagnado, 2018). In criminal justice system, where experts routinely present their interpretation of evidence such cognitive biases can lead to wrongful evaluation of a hypothesis because of lack of knowledge or a misinterpretation of the evidence. Evidence itself can be misleading because either it is irrelevant or it is unreliable. An empirical study for identifying misleading evidence drew information from case transcripts of rulings in a 7- year period; the study found that 218 applications were successful on appeal, and that 235 cases included misleading evidence (Smita, Morgana, & Lagnado, 2018). The study found that the majority of successful appeals were not based on the presentation of new information but were based upon the same materials available in the original trial; the most common evidence types were witness, forensic, and character evidence and that the majority of misleading evidence types related to the interpretation of the evidence at activity level (Smita, Morgana, & Lagnado, 2018). The crucial finding of this study is that there was a lack of transparency in the relationship between evidence and hypotheses due to which misleading evidence was presented before the courts (Smita, Morgana, & Lagnado, 2018). When compared with the number of successful appeals based on the same materials presented before the court in the original trial, it can be suggested that there is a significant issue of expert evidence being misleading in the courts and that this evidence plays a role in leading to incorrect decisions in the courts. This is supported by the fact of there being many successful appeals based on the same materials that was presented in the original trial. Cognitive bias is not intentional in all instances; there are many instances of unintentional cognitive bias (The Parliamentary Office of Science and Technology, 2015). The way unintentional cognitive bias affects the decision making process in the courts is explained as follows:

“Information which bypasses awareness can still influence decision making. While information is processed in this way to maximise limited cognitive capacities, one consequence is that people are not always aware of all of the factors that guide their decisions. Decision making is therefore susceptible to the influence of irrelevant factors and preconceptions, which can lead to suboptimal reasoning. The unintentional reasoning errors that people systematically make are collectively known as ‘cognitive biases’” (The Parliamentary Office of Science and Technology, 2015, p. 1).

As noted above, cognitive biases are generally unintentional and they are resultant of the susceptibility to influence of irrelevant factors and preconceptions by the experts who may not realise that they are compromising their decision making through the influence of such irrelevant factors and preconceptions that they may have because they may not realise the nature of these preconceptions and how these are impacting them. As noted above, cognitive biases are unintentional reasoning errors. Therefore, while the person making the decision may not be able to understand how the cognitive reasoning is compromised by such reasoning errors. There are three methods that are generally used for testing expert bias in the justice system. These approaches may include analysing real cases by the researchers, case simulations and testing practitioners. For case simulations, researchers stage mock trials, that allow them to control variables, unlike analysis of real cases in which variables are not controlled by the researchers; thus, for case simulations, researchers have two groups of participants that view exactly the same case with just one feature changed and then the researchers consider how that one feature affects the verdicts (The Parliamentary Office of Science and Technology, 2015). For testing practitioners, researchers test for unintentional bias in actual practitioners in the justice system by applying Implicit Association Test that measures unintentional attitudes (The Parliamentary Office of Science and Technology, 2015). Then the researchers establish correlations between the biases they find to behaviour in real cases after testing the practitioners like police officers, experts and other people who are routinely involved in criminal justice system. Due to the impact of the cognitive biases in the criminal justice system, there is increasing interest in the need to address the problems caused by cognitive bias in the criminal justice system (The Parliamentary Office of Science and Technology, 2015). Therefore, the Judicial College that trains the courts’ judiciary in England and Wales does offer training and information about cognitive biases as a way of ensuring that some training on cognitive bias is being given to judicial officers (The Parliamentary Office of Science and Technology, 2015). Cognitive psychologists are also now increasingly involved in training on cognitive biases for employment tribunal judges in the UK since 2015 (The Parliamentary Office of Science and Technology, 2015). Rape stereotypes are now being taught to the judicial officers in the UK so that there is some mitigating of the effects of such stereotypes in rape cases (The Parliamentary Office of Science and Technology, 2015). Lord Neuberger as President of the Supreme Court has specifically cautioned judges to consider how their unconscious attitudes impact their decision making in the courts (The Parliamentary Office of Science and Technology, 2015). Lord Neuberger also says that as there is now sufficient evidence that cognitive biases affect human decision making and affects the justice system and such effects need to be mitigated (Neuberger, 2015). He also advises giving access to researchers to all areas of the justice system without interruping or affecting cases and also encourages use of education and strategies to limit the effects of cognitive biases for key participants in the criminal justice system, including judges, magistrates and jurors (Neuberger, 2015).

Cognitive psychology and cognitive bias in expert reports

Cognitive psychology is the science that focuses on the higher functions of the brain, which are related to language, thought processes, learning, perception and analytical skills and the way they affect our behaviour. As such, cognitive abilities do inform decision making. Whilst analysing case information, experts can inadvertently get confused by paradoxical connections between pieces of evidence which then heavily affects their opinion. An example of such logical error is cognitive bias – a “systematic (that is non-random, and, thus, predictable) deviation from rationality in judgement and decision making” (Blanco, 2016). As discussed in the above section, cognitive bias reflects on the difference between the objective truth or reality and the representation of the same in the mind of the decision maker. Thus, the factors that lead to cognitive bias have the effect of distorting truth representation in the mind of the decision maker so that the decision maker does not understand how the representation in his mind is not the objective truth but an illogical representation of the same. Positive and negative implications of the causal illusion have been reported in research (Blanco, 2017). This causal illusion is related to the illogical representation of the truth and it has a close nexus with the cognition of the decision maker. In the field of psychology, this phenomenon of the causal illusion is explained as follows:

“In ancestral environments, with the pressure to make decisions and act quickly, it is probably the case that missing a meaningful pattern is costlier and less adaptive than illusorily perceiving one when there is none (e.g., it is better to run away upon sighting a potential predator than waiting until it is clearly visible, but too close for escape). Admittedly, the balance of the least-costly mistake can be reversed under particular circumstances that favour a more conservative criterion (i.e., a situation in which it is preferable to miss a valuable opportunity to succeed, instead of making the opposite mistake and developing an illusion)” (Blanco, 2017, p. 57).

Thus, making cognitive errors may be something that human are wired to do because from an evolutionary context, humans were required to make decisions and act on them in a fast paced environment, which led to the process of decision making which sees people avoid the least costly mistake. Causal illusion can have certain implications for the decision making process of the individual. It can lead to persistence of behaviour in the decision maker as the decision maker is influenced by causality caused by the illusion where the link between the decision and the effect is already established in their minds; it can lead to reduction of anxiety and stress as the decision is motivated by the illusion that making such a decision would lead to fewer ill effects for the decision maker; it can lead to a feeling of being in control and uplifting of mood, which can then make the decision maker reinforce the illusion and the continue with behaviour persistence (Blanco, 2017). Cognition involves thinking and the point of the exercise of thinking is to give the thinker the true beliefs about the world (Thau, 2002). However, cognitive psychology shows us how the beliefs of the thinker may actually be misrepresentation of the truth of the world (Thau, 2002). This misrepresentation may be due to the preconceived notions, expectations or confirmation by the thinker (Thau, 2002). Evolutionary perspectives can be used to explain why such misrepresentation may occur in the minds of individuals (Haselton, Nettle, & Murray, 2015). For an evolutionary psychologist, cognitive biases could have evolved because they positively impacted fitness and were part of design features of human cognition rather than design flaws (Haselton, Nettle, & Murray, 2015). However, such evolutionary perspectives may not be able to explain why cognitive biases occur in experts within the criminal justice system. The development of cognitive biases are not always related to the intention of the experts as there is now sufficient body of evidence that shows that even the most well intentioned experts may be susceptible to cognitive bias (Dror & Cole, 2010 ). Within the field of forensic science, there are a number of problematic issues related to the cognitive bias of the experts. One issue is that even the erroneous judgements of forensic experts are persuasive in the legal context especially when the expert themselves is prone to honest belief in the veracity of his judgement. Another problem is that many individual examiners are found to be “reluctant and resistant to acknowledge, accept, and take proper action to counter these biases” (Dror & Cole, 2010 , p. 162). Another problem is that within forensic science practice itself, cognitive bias has been historically conceptualised as an ethical issue, which can be overcome by moral discipline, whereas psychology regards it as an inherently cognitive issue which can only be reduced through bias-minimising actions (Dror & Cole, 2010 ). This difference between the approach of the practitioners and the perspective of the psychological approaches to cognitive bias is essential to understanding why it becomes difficult to reconcile the two approaches. In cognitive psychology research at least seven sources of cognitive bias of experts have been identified with relevance to forensic experts, which do not have a basis in intentional bias showing the futility of thinking about cognitive bias from an ethical viewpoint (Dror,, 2017). These sources are depicted below in Figure 1.

The sources of biases are related to case specific sources, environment and culture specific sources, and human nature specific sources. As can be clearly seen, these sources operate from different contexts and impact cognitive decision making in different ways. Case Evidence is noted at the top of the taxonomy and it relates to the actual evidence collected from the crime scene, such as, fingerprints, handwriting, DNA, voice recording, and bite marks to name a few (Dror,, 2017). Evidence may be a source of cognitive bias for the expert unintentionally because information it may convey irrelevant information. Similarly, Reference Material may cloud the judgment of the expert by presenting him with too much information. This can be minimised through Linear Sequential Unmasking, which is discussed in another section of this dissertation. The biases that are related to environmental and social factors may lead to expectation or confirmation biases by the experts where the experts believe certain information more and subject it to lesser scrutiny as it relates to pre conceived expectations. The environmental and cultural factors can also relate to the culture of the organisation and the training received by the expert. At a more fundamental level, cognitive errors occur due to human nature or the way cognitive architecture and the brain is structured. This has been explained as the level at which “the very making of us, as humans, and how our brains work, introduces a whole set of biases” (Dror,, 2017, p. 545). It is at this level that we see evolutionary psychology playing a role to explain how human brain may itself be wired to make certain kinds of cognitive errors. Psychology has been able to however, develop best practices for obtaining eyewitness identifications, by showing how exposure to prior information about the case can bias the judgement of the experts (Dror,, Kassin, & Kukucka, 2013). Reforms are needed to the criminal justice system to ensure that such biases are minimised; for instance in the case decided by the Court of Appeal, the court held that the prior information of DNA matching did not vitiate the expert identification (R. v Rogers [2013] EWCA Crim. 2406 , 2013), whereas psychology may argue that such exposure is a concern for the veracity of the expert opinion (Dror,, Kassin, & Kukucka, 2013). In the context of witness communications, establishing standards for such communication may be one way in which such biases may be reduced or their effects mitigated (Wilson, 2010).

Experts and expert evidence

Providing expert evidence in Court is a privilege. An expert is a highly trained and experienced individual who is suitably qualified to provide information or opinion or both to the court in order to assist with matters in which the court or the jury would lack expertise. The expert witness provides either a written report or oral evidence, depending on the nature of his instructions. According to The Criminal Procedure Rules 2010 “An expert must help the court to achieve the overriding objective by giving objective, unbiased opinion on matters within his expertise. This duty overrides any obligation to the person from whom he receives instructions or by whom he is paid. This duty includes an obligation to inform all parties and the court if the expert’s opinion changes from that contained in a report served as evidence or given in a statement.” (The Criminal Procedure Rules 2010, no 60 (L.2) Part 33 Rule 33.2). There are four recognised attributes to an expert witness. These include Assistance, which is the ability to assist the Judge and Jury in their decision-making process in matters where neither have knowledge or life experience. If the Judge and Jury can draw their own conclusions from the facts presented in Court without any help, the expert witness will not be required. Next, we include Relevant expertise, which to be accepted as having relevant expertise, the expert must be still in practice in order to maintain and develop their experience, must be an expert in the actual subject where they testify, must have recently seen a case in his own practice and his views must be widely held. The next is Impartiality as per which the opinion provided must be independent, unbiased and objective regardless of whom instructs and pays him, both in the expert’s report and when giving evidence in Court. Also, the expert witness must inform the Court when the questions asked are leading them outside of their expert area or if their opinion has changed from a previous report or statement. Finally, we have Reliability, which speaks to the fact that the evidence must pass the “general acceptance test – the thing from which the deduction has been made must be sufficiently established to have gained general acceptance in the particular field to which it belongs” (Frye vs United States 1923). In English courts, the common law “reliability test” applies depending on "whether the subject matter of opinion forms part of a body of knowledge or experience which is sufficiently organised or recognised to be accepted as a reliable body of knowledge or experience" (Regina v Bonython: 1984. Ratio: (South Australia Supreme Court).

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Recommendations: Mitigating effects of bias

Cognitive bias still has not been understood well in the field of forensic science as there is a long way to go before we are able to understand how cognitive bias develops for the forensic scientist. However, in the field of psychology, we now have sufficient research to show us how cognitive bias plays a role in the formulation of incorrect assumptions by the expert. The next step is to consider the ways in which the effects of the cognitive bias can be mitigated. At this time, there are some well accepted methods that are proposed to mitigate the role of cognitive bias in the field of forensic science. There are some methods that are already being proposed to mitigate the effects of bias in expert evidence. With regard to contextual bias, one method to limit it is to ensure that the expert only has information about the case that is relevant to the analysis. It is important to ensure that only task-irrelevant information is presented to analysts as a way of sequential unmasking (Forensic Science Regulator, 2015). As a more structured approach to reference materials is adopted, the experts will be able to revisit the initial analysis of trace evidence as long as they also keep the changes to the initial findings are documented, with an explanation of the reasons. However, the policies adopted should well designed. This ensures that the decision process is transparent and disclosable (Forensic Science Regulator, 2015). Another method being proposed for mitigation of cognitive bias impacts in the criminal justice system is to assess individuals for susceptibility to psychological and cognitive influences as such susceptibility varies between individuals (Charlton, Fraser‐Mackenzie, & Dror, 2010). The proposal is to assess for such susceptibilities as part of the recruitment or selection procedures for new staff, for instance, fingerprint examiners (Charlton, Fraser‐Mackenzie, & Dror, 2010). It is suggested that proficiency-testing programme be used for making such assessment for staff recruitment for specific forensic roles to ensure that individuals for more susceptibility to cognitive bias are not selected. With regard to role effects bias, there are already some measures that are in place to mitigate the effects of these biases. Role effects, as explained earlier, are the biases that occur when experts identify themselves with one or the other side in a case and then getting subconsciously influenced by acting on behalf of chosen side. First, it has to be remembered that the experts are not supposed to be acting on one or the other side as the principal client for them is the criminal justice system. For experts belonging to the forensic science, the Forensic Science Regulator’s Codes stipulate that practitioners have overriding duty to the court and to the administration of justice; and that the act with honesty, integrity and impartiality (Forensic Science Regulator, 2015). Section 7.2 of the Codes emphasise on the duty of the forensic scientists to avoid any conflicts of interest. Threats to impartiality are also to be avoided including those that are resultant of being the sole reviewer of critical findings, over-familiarity with another person instead of relying on objective evidence, or having organisational and management structures that could be perceived to reward, encourage or support bias (Forensic Science Regulator, 2015). The most important finding of this dissertation is that there is still a long way to go before we can understand and critically appreciate the role played by human cognition in forensic work and understanding is “the first step on the long journey of researching and gaining a better understanding of what underpins forensic decision-making” (Dror,, 2017, p. 546).

Conclusion

Cognitive bias has come to be accepted as a common feature in criminal justice system which affects the expert opinion and has implications for the decisions of the courts. Cognitive bias is no longer just related to ethics of the expert because psychology has shown that most of the cognitive bias is unintentional. There are many reasons that may give rise to cognitive bias which may be related to the factors specific to the case, as well as environmental/cultural factors, or factors that are related to the way in which human cognitive architecture and brain is structured. Given the ways in which criminal cases have come to depend on expert evidence especially in the field of forensics, it is now essential that the role of cognitive bias in criminal justice system is better appreciated and critically responded to. Psychology will play a major role in this area as it is through psychological research that we will be able to identify the factors responsible for cognitive bias as well as the ways in which such biases can be mitigated in their effects. To some extent, research in cognitive psychology has been able to provide some insights in this area however, as research in this area is recent in nature, there is much to be understood in future research as well. In the meantime, the mitigating measures that are proposed in cognitive psychology can be applied. In the UK, there is greater appreciation of such measures as they are being gradually accepted in the forensic science field. However, as there is not as yet enough research on this area, there is a need to combine psychology and public law research to come to better processes for forensic science and for judges and juries to be better educated on the way cognitive bias can play a role in the way the experts present their evidence to the courts. The possibility of cognitive bias was historically rejected in the field of forensic science but with greater awareness on this issue, it must be appreciated that much of the bias can be unintentional and for that reason cognition based and not ethics based measures need to be explored and adopted.

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