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TheDirtyDozen:12SourcesofBiasinForensicNeuropsychologywithWaystoMitigate

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DOI:10.1007/s12207-015-9235-1

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The Dirty Dozen: 12 Sources of Bias in Forensic Neuropsychologywith Ways to Mitigate

Paul M. Richards1 & Jennifer A. Geiger1 & Chriscelyn M. Tussey2

Received: 10 September 2015 /Accepted: 16 October 2015 /Published online: 31 October 2015# Springer Science+Business Media New York 2015

Abstract The ever expanding role of a forensic neuropsy-chologist in civil litigation has rightfully led to a higher levelof expectation for this expert, in realms such as clinical andcourtroom knowledge, objectivity, and work product utility.The onus is on forensic neuropsychologists to ensure thatthese expectations are met. Recognizing that bias is inherentin clinical and forensic work, it is imperative that in highstakes situations such as forensic neuropsychological assess-ment, the evaluator is proactively conscientious in recogniz-ing, and minimizing, the effects of these biases. This articlehighlights 12, of many, common biases about which the pru-dent forensic neuropsychologist should always be mindful of,during evaluation as well as the provision of deposition or trialtestimony. Role, cognitive, and practice biases are defined andillustrated with examples. Specific suggestions are extractedfrom both empirical literature and forensic experience on howto recognize and mitigate these biases. The informationcontained in this article is intended to provide sound and prac-tical strategies that can be useful for forensic neuropsycholog-ical practitioners. Attorneys will also find the content usefulwhen working with such experts, including during depositionand cross examination preparation.

Keywords Forensic neuropsychology . Civil litigation .

Testimony .Neuropsychologicalassessment .Expertwitness .

Cognitive bias . Confirmation bias

Introduction

The field of forensic neuropsychology has proliferated formore than two decades with continued growth expected inthe foreseeable future (Kaufmann, 2009; Kaufmann &Greiffenstein, 2013). This time period has seen publicationof numerous edited books on this topic (Boone, 2013;Heilbronner, 2008; Horton & Hartlage, 2010; Larrabee,2005, 2012; McCaffrey, Williams, Fisher, & Laing, 2004;Sweet, 1999; Young, Kopelman, & Gudjonsson, 2009).Sweet, King, Malina, Bergman, and Simmons (2002) docu-mented the Bprominence^ of forensic neuropsychology vis-à-vis an increasing number of peer-reviewed journal articles andcontinuing education opportunities at national conferences onthis topic. Sweet, Meyer, Nelson, and Moberg (2011) reportedthat approximately 72 % of surveyed neuropsychologists pro-vide forensic evaluations and consultation services.Greiffenstein and Kaufmann (2012) recently concludedBGrowth in forensic consulting for neuropsychology isoutpacing every related brain-behavior expertise and thegrowth is accelerating^ (p.14).

Neuropsychologists are increasingly retained orsubpoenaed to provide forensic and clinical opinions relatedto diagnosis, prognosis, causality, and permanency regardingindividuals with a host of compensable conditions such astraumatic brain injury, anesthesia/surgical accidents, carbonmonoxide poisoning/toxic exposure, and post-traumatic stressdisorder (Richards & Tussey, 2013). Similar to expert wit-nesses in any field, the forensic neuropsychologist must striveto be objective and unbiased to maximize effectiveness andcredibility. Triers of fact (i.e., judge, jury, and arbiter) willlikely discount or ignore the testimony of those experts whoare perceived as biased, advocates for one side or the other, orhave their own personal, financial, or political agenda to pro-mote. Skilled attorneys will probe for bias during deposition

* Paul M. Richardspaulmrichards@msn.com

1 Independent Practice, Louisville/Denver, CO, USA2 Independent Practice, New York University School of Medicine/

Bellevue Hospital Center, New York, NY, USA

Psychol. Inj. and Law (2015) 8:265–280DOI 10.1007/s12207-015-9235-1

and seize every opportunity to expose the opposing neuropsy-chologist’s bias in trial which can prove pivotal in the eyes ofjudge and/or jury and influential in judgment. In this Bage ofthe internet,^ even a cursory online search reveals articlessuch as BExposing An Expert Witness’ Bias During CrossExamination: Collateral Attack^ in which Rubinowitz andTorgan (2013) offer a step by step guide with specific ques-tions to demonstrate bias and thereby discredit the expert wit-ness. Quite simply, not only does the effective forensic neuro-psychologist have to be imminently qualified regardingeducation/experience and employ scientific and reliable meth-odology, he/she must take steps throughout the entire expertwitness process to maintain objectivity and impartiality.Although each forensic case is different with unique expert-examinee dynamics and differing relationships with theretaining attorney, there are frequently common threats to ob-jectivity and sources of bias that the seasoned expert sees timeand again.

In this article, we discuss 12 different sources of bias thatthe forensic neuropsychologist may encounter in his/her eval-uation or provision of expert opinions and testimony. As evi-dent in Appendix 1, the first four biases (role, financial,referral source, and self-report) are logistical and administra-tive, pertaining to how the neuropsychologist has set up theevaluation and the source of information relied upon. The nexttwo are statistical in nature (under-utilization of base rates andignoring normal variance in test scores). The final six biasesmight best be described as a subgroup of cognitive, personal,and attributional biases (confirmation, personal/political,group attribution, diagnosis momentum, good old days, andoverconfidence). This list is certainly not exhaustive as othersources of bias exist. Starting 60 years ago with the seminalwork of Meehl and Rosen (1955), researchers in the fields ofsocial and cognitive psychology as well as behavioral researchhave identified, discussed, and studied social, attributional,cognitive, and experimental biases including ways they mightaffect the psychologist’s judgment and decision making pro-cess. However, a review of all these biases is beyond the scopeof this article, and instead, we focus on some that are frequent-ly cited in the literature as potentially problematic and that aretopics of interest and study among neuropsychologists at na-tional conferences and workshops. Although there may beapplicability to the criminal arena and with pediatric popula-tions, the biases that follow are discussed primarily within thecontext of personal injury civil litigation with an adult popu-lation. Other authors (Deidan & Bush, 2002; Martelli, Bush,& Zasler, 2003) have identified a number of biases and ethicalissues in clinical neuropsychology and listed ways to address;the present article builds on prior work in this area with agreater emphasis on forensic practice. We hope that an explo-ration and review of these issues will promote future discus-sion and research and thereby improve the objectivity of thoseneuropsychologists who choose to provide forensic services

or those who unwillingly enter the legal arena (i.e.,subpoenaed to testify as fact or treating expert). The formatwe follow in this article is to first define the potential source ofbias with examples of what can go wrong in such instancesfollowed by recommendations of ways to mitigate.

Role Bias: Conflating Clinical and Forensic Roles

Clear distinctions exist between clinical and forensic roleswith precautions to not mix these roles (Richards & Wortzel,2015; St rasburger, Guthe i l , & Brodsky, 1997) .Neuropsychologists routinely receive clinical (non-forensic)referrals and provide evaluation, treatment, and consultationservices to these patients. The treating neuropsychologist fre-quently attempts to develop a therapeutic alliance with thepatient which emphasizes trust and empathy and may viewhim/herself as an advocate for the patient in order to promotehealth, well-being, and recovery. At some point during or afterthis process, the neuropsychologist may receive an informalattorney request or subpoena to provide testimony about a pastor current patient who has been the recipient of clinical ser-vices. In this scenario, the neuropsychologist is typically re-ferred to as a Bfact witness^ or Btreating expert.^ It is permis-sible for this clinician to testify under oath regarding factsabout his/her patient such as start, duration and completionof care, methods of treatment employed and outcome, work-ing diagnosis, payments received, and so on. However, thetreating neuropsychologist has not performed a forensic eval-uation and therefore cannot provide certain expert opinions orformulate conclusions from the reports of others, and it iswhen he/she Bchanges hats^ and provides forensic opinionsregarding causality, permanency of a condition, and otherpsycho-legal matters that potential role conflict and/or ethicalissues arise.

In marked contrast, the retained expert has been hired by anattorney or other third party to evaluate a plaintiff to renderforensic opinions, clearly spelling out the limits of confiden-tiality before beginning the evaluation with a primary goal ofaiding the legal process. He/she has to conduct an evaluationthat holds up to the scrutiny of the adversarial process that caninclude the opposing neuropsychologist’s analysis/critiqueand vigorous cross examination. The retained expert has tometiculously corroborate examinee self- report with collateraldata, never provides treatment to the examinee, and avoidsany perception of advocacy, while attempting throughout thisprocess to be objective and impartial.

Greenberg and Shuman (1997) listed important differencesbetween therapeutic and forensic relationships, discussinghow blurring these boundaries lead to Brole conflict^ andeven, BIrreconcilable Conflict.^ These authors distinguishedclinical from forensic roles by noting they typically involvecompeting interests that are often at odds. They described the

266 Psychol. Inj. and Law (2015) 8:265–280

role conflict as that of a dual role, violating ethical principlesestablished by the American Psychological Association.Malina, Nelson, and Sweet (2005) concluded that BWriting aforensic report after providing treatment is consistent withassuming a dual role with the patient-litigant, and harm tothe therapeutic alliance, or threat to the neuropsychologist’sobjectivity are real possibilities^ (p. 30). Melton, Petrila,Poythress, and Slobogin (2007) described mental health pro-fessionals who serve as the retained expert of a patient previ-ously or currently being treated as a Bdouble agent,^ whereasRichards and Wortzel (2015) referred to this person as a Bdualagent.^

The BSpecialty Guidelines for Forensic Psychology^(American Psychological Association, 2013) addressestherapeutic-forensic role conflicts in Guideline 4.02.01 asfollows:

Providing forensic and therapeutic psychological ser-vices to the same individual or closely related individ-uals involves multiple relationships that may impair ob-jectivity and/or cause exploitation or other harm. There-fore, when requested or ordered to provide either con-current or sequential forensic and therapeutic services,forensic practitioners are encouraged to disclose the po-tential risk and make reasonable efforts to refer the re-quest to another qualified provider. If referral is not pos-sible, the forensic practitioner is encouraged to considerthe risks and benefits to all parties and to the legal sys-tem or entity likely to be impacted, the possibility ofseparating each service widely in time, seekingjudicial review and direction, and consulting withknowledgeable colleagues. When providing bothforensic and therapeutic services, forensic practi-tioners seek to minimize the potential negative ef-fects of this circumstance (P. 11).

Table 1 below summarizes some of the primary role differ-ences between a fact witness/treating expert and a retainedexpert. This list is not exhaustive or exclusive but highlightssome key differences culled from the literature that forensicneuropsychologists should consider.

Regarding mitigation and avoidance of these situations,Woody (2009) articulated the ethical issues of Bmultiple rolesin forensic services^ and then strongly recommended that thepsychologist decline or withdraw from one of the roles. Morerecently, Brodsky (2013) provided recommendations for howto best handle situations in which the treating expert is askedto provide forensic opinions in a report and/or during testimo-ny. We concur with the above authors and posit that the sim-plest and most appropriate way to avoid potential bias in thisarea is for the fact witness or treating expert to not provideforensic opinions, testifying within the boundaries of what he/she was hired to do and not conflating roles. When pressed by

counsel to do such prior to or during testimony, responsesmight be: BI did not conduct the type of evaluation necessaryto answer your question^ or BI conducted a clinical but notforensic evaluation and therefore, do not have the basis toform an opinion about what you asked.^ Counsel’s inevitablefollow up questions to these responses afford additional op-portunities for the expert’s explanation of the inherent issues.

Financial/Payment Bias

Serving as an expert witness can be complex and stressful forthe neuropsychologist, and what should be the most straight-forward component of this process (clear and ethical paymentarrangements) sometimes proves confusing or frankly uneth-ical.We next review the continuum of reimbursement arrange-ments that vary from straightforward to murky to highly bi-ased. First, it is commonly agreed that accepting a forensiccase based on any form of contingency payment arrangements(payment of the expert’s fees is contingent on legal outcome)is inappropriate with an inherent conflict of interest thatshould be avoided (Binder et al., 2012; Bush, Connell, &Denney, 2006). Such practices potentially bias the expert or,at a minimum, contribute to the perception of bias. Second andless straightforward than contingency financial arrangementsis a Blien^ that may also be termed a Bletter of protection^(Woody, 2011). In this instance, the expert signs a lien agree-ment with the retaining attorney which Bprotects^ his/her bal-ance due and seemingly promises payment for servicesrendered when/if the case settles, regardless of the outcomeof the case. This presumably covers those instances in whichthe patient does not have the finances, health insurance, orother resources to cover the costs of neuropsychological ser-vices such as evaluation, treatment, and consultation.However, what initially sounds like a creative way to helpsomeone who is indigent because of a compensable accidentor condition is fraught with ethical pitfalls as discussed byWoody (2011) who ultimately discourages the psychologistfrom engaging in this practice. The neuropsychologist whoaccepts a lien as a potential source of payment has to answerand defend the inevitable question of: BDoctor, isn’t it true thateventual payment of your final bill is 100 % dependent on theoutcome of this case?^ Personal injury cases frequently takeyears to resolve, and there is no guarantee that the plaintiff willrecover anything let alone the full amount demanded or somepercentage thereof. Even the most principled neuropsycholo-gist has to fight the reality or perception of bias that his/hertestimony is somehow shaded or adjusted to help insure asuccessful judgment so that the statement for services ren-dered is paid in full. Anecdotally, some neuropsychologistscharge interest for past balances which places him or her inthe untenable position of somehow evaluating the probabilityof eventually getting paid and then serving as a money lender

Psychol. Inj. and Law (2015) 8:265–280 267

who calculates interest on past due amounts. WhereasGuideline 5.02 of the SGFP states that: BLetters of protection…are not considered contingent fees unless payment is depen-dent on the outcome of the matter,^ we concur with Woody(2011) that acceptance of a lien/letter of protection poses po-tential ethical, legal, and business pitfalls and should thereforebe avoided.

The third and most straightforward form of payment isBFee for Service^ where the neuropsychologist is paid forhis/her time, irrespective of legal outcome. We have previous-ly (Richards & Tussey, 2013) recommended that before pro-viding any forensic services, the neuropsychologist has theretaining attorney/party sign an Expert Witness RetentionContract that clearly spells out in a transparent way the ex-pert’s fees including retainer (if any) and duties. Babitsky andMangraviti (2005) recommend that experts BGet paid up front.An expert for the plaintiff who fails to do this may create a defacto contingent fee situation where the expert is not likely tobe paid unless the plaintiff wins^ (p. 46).

There are, of course, other forms of payment such as probono and sliding fee arrangements, and some disability insur-ance carriers and IME companies request that the expert’s feesbe Bcapped^ at a set amount. Ultimately, the neuropsycholo-gist has to decide (and perhaps explain during testimony) whyhe/she deviated from their standard practice for this one par-ticular case at hand. It is imperative in these scenarios that theneuropsychologist not Bcut corners^ (e.g., skip some tests, notreview all the relevant records, or prepare insufficiently) be-cause he/she is not compensated or only partially paid.Providing pro bono services is laudable, but the forensic neu-ropsychologist must examine his/her subtle and obvious mo-tivations for doing such. Colleagues occasionally provide probono or discounted forensic services out of empathy forimpoverished litigants who have been Bwronged and needtheir day in court^ or are trying to establish a reputation earlyin their career, practices that might best be saved for the clin-ical but not forensic arena. Finally, there are Bback door^referrals in which an attorney asks a treating physician to refer

the patient/plaintiff to a neuropsychologist, hoping an evalua-tion can be paid by health care insurance or a governmentpayer such as Medicare or Medicaid. However, most if notall commercial insurance carriers and government health en-tities exclude forensic evaluations as they are not medicallynecessary. One would certainly have to question the ethics andpotential bias of any neuropsychologist willing to disguisecharges for hours of record review and report writing as clin-ical rather than forensic.

Referral Source Bias (and Retaining AttorneyPressure)

Rule 26 of the Federal Rules of Civil Procedure (1975) re-quires retained experts who are disclosed as witnesses in aproceeding to submit, among other documents, a list of pasttestimony (deposition and trial) over the preceding 4 years.This disclosure must include case caption, number, and juris-diction and whether the expert was retained by the plaintiff ordefense; however, there is no requirement to disclose caseoutcome or other information. This BRule 26 disclosure^ oftenprovides fodder for the cross examining attorney to probe for,insinuate or assert bias based on a preponderance of testimonyfor one side or the other. However, the breakdown of whereone’s referrals come from is not indication of bias in and ofitself. As noted by Greiffenstein and Kaufmann (2012), BAsimple ratio of plaintiff to defense cases is not compellingevidence for objectivity versus partisanship. It is a reality thata [forensic neuropsychologist’s] career trajectory increasinglyattracts retention by one side or the other. There are manyreasons for this including word of mouth, aggressive versusconservative neurodiagnostic approaches, and scientist- prac-titioner ethos versus pure clinical orientation^ (p. 57).

On the other hand, one could easily speculate that a reasonwhy only plaintiff or defense attorneys will repeatedly or ex-clusively retain a particular forensic neuropsychologist is be-cause that expert is predictable, tending to consistently proffer

Table 1 Primary role differences between a fact witness/treating expert and a retained expert

Fact witness/Treating expert Retained expert

1. Who is client The patient Retaining attorney; Court

2. Forms doctor–patient relationship Yes No

3. Provides treatment & Explains test results Yes No

4. Advocates for patient Yes No

5. Relies extensively on records and other collateral contacts Not Necessarily Yes

6. Services provided within adversarial context No Yes

7. Provides forensic opinions on causality & permanency No Yes

8. Knowledgeable about facts of legal matter/claims made Not necessarily Yes

9. Fiduciary responsibility to whom The patient Retaining attorney; Court

10. Professional services paid by whom The patient and/or insurance company Retaining attorney; Court

268 Psychol. Inj. and Law (2015) 8:265–280

opinions that are helpful for that side while hindering theopposing side’s case. Why would an expert who only acceptsplaintiff or defense cases, and especially those situations inwhich one particular attorney or law firm accounts for all ora majority of referrals, not become jaded over time and grad-ually conceptualize cases from that standpoint? If the expert isemploying a Bscientific method^ to forensic neuropsychologyas advocated by Larrabee (2012), that person should theoret-ically be equally conversant and willing to accept both defenseand plaintiff cases, assuming of course ethical payment andother arrangements were in place.

Lees-Haley (1999) called a 50–50 forensic referral patternan B…unfounded but widely circulated myth that testifying50 % for plaintiff and 50 % defense is evidence of absence ofbias. This myth is a problem in the context of debiasing be-cause it is used to imply lack of bias when ‘50-50’ may actu-ally be evidence of just the opposite. The 50–50 myth is aclassic case of an unexamined proposition that survives byrepetition without critical review^ (p. 14). However, as one'syear's of forensic practice increase, it is difficult and perhapsunrealistic for the neuropsychologist to maintain a true 50–50referral pattern, and we are not aware of studies addressingbias (or lack thereof) with this phenomenon. It may be that thereferral ratio is not as important as a wide referral network,and, therefore, we concur with Martinez (2014) who noted:BDiversifying a forensic practice may reduce pressure to sat-isfy the referral source due to interest in future referrals^ (p. 2).In summary, it may be common for neuropsychologists whotestify exclusively for one side or the other to get type-cast aseither a Bliberal plaintiff neuropsychologist^ or Bconservativedefense expert.^ However, rather than being concerned aboutthese labels, it is much more important for the forensic neuro-psychologist to guard against automatically offering favorableopinions for the side that hired them.

Somewhat more problematic than where a neuropsycholo-gist’s forensic referrals come from are more subtle but potentbiasing factors that begin the moment the phone rings with anattorney referral. At that time, the referring attorney may at-tempt to have the expert Bjoin the team^ with statements suchas BDoctor, I know you will do your own evaluation but I’msure you will find that Mrs. Smith sustained a traumatic braininjury (or did not).^ These types of statements begin a push toaffiliate with the referring attorney with subtle pressure toaccept their prevailing view. Attorneys by definition are zeal-ous advocates and persuasive not only to judge, jury, andclient but their expert(s) as well. We encourage resisting attor-ney sweeping case conclusions before the neuropsychologistreviews all the records and conducts his/her evaluation, settingappropriate boundaries up front such as: BI appreciate thatinformation but I’d like to be the judge of whether Mrs.Smith sustained a brain injury after I complete myevaluation.^ Information received at the onset of a case shouldbring into consideration the long-studied psychological

principle of primacy bias or anchoring, that is, early informa-tion may lead to premature conclusions that are difficult toabandon as the case unfolds. The simplest way to counterpotential bias in this area is to limit early attorney meetings.The focus of the initial attorney-expert contact should pri-marily be administrative in nature to rule out potentialconflicts of interest, assure competency with the condi-tion in question, and provide fees/policies and othernecessary documents (e.g., expert witness retentionagreement, CV, and disclosure of past testimony).

Post evaluation, attorneys will sometimes ask the neuro-psychologist to make report changes that can vary fromminorfactual mistakes (incorrectly reporting someone has three sib-lings when, in fact, it is two) to substantive (changing forensicopinions about diagnosis or causation). The forensic neuro-psychologist should never alter a report that has been final-ized, even if it has only been sent to the referring attorney whopromises to shred it. Such requests have to be evaluated ac-cording to accuracy and can be accomplished in the form of anaddendum or supplemental report where there is a paper trailof the neuropsychologist’s decision-making process with fulldisclosure. Factual inaccuracies can and should be corrected;however, requests for more substantive changes have to beevaluated on a case by case basis. For instance, if additionalkey records or facts become available after report completionand that information changes forensic opinions, an addendumis the appropriate forum to document using language such asBAfter reviewing the following records on this date, my opin-ion of X changes to Y for the following reasons.^ Otherwise,if the retaining attorney is requesting that an expert alter his/her report with substantive changes in the absence of new factsor simply to bolster their legal case, a firm but polite BNo^ isrecommended with explanation that the expert is not willing tocompromise his /her ethics and integrity. Setting this type ofethical boundary up front communicates the expert’s unwa-vering conviction he/she cannot be manipulated or bulliedwhich often paves the way for a more productive workingrelationship down the road.

Finally, after a judge or jury has delivered a verdict,experts are sometimes tempted to call the retaining at-torney to find out Bhow did we do^ with maybe aspecific question of Bhow much did the jury award theplaintiff?^ This communicates an emotional investmentin the outcome that should be avoided. Some expertsmay have need for being perceived as the Bstar witness^in high profile cases or Bhitting a homerun^ with theirtestimony which only communicates partisanship.Moreover, if an expert is that intrigued by a jury ver-dict, he/she was likely biased from the start and mayhave approached the forensic evaluation from the stand-point of winning vs. losing a case or defeating the op-posing expert, factors inconsistent with the awarenessand mitigation of bias that we advocate in this article.

Psychol. Inj. and Law (2015) 8:265–280 269

Self Report Bias (Need for Corroborative Data)

In psychology doctoral training programs and medical school,the fledgling clinician is typically taught to Blisten to thepatient.^ This admonition also holds true for the forensic neu-ropsychologist, yet, it must be tempered with a statementabout the critical importance of not relying exclusively or evenextensively on examinee self report, stressing the need to sup-plement subjective history with a thorough review ofcollateral/corroborative information. Along with interview/mental status exam and neuropsychological test results, a thor-ough record review helps form the triad of an evidence-basedand scientifically sound forensic evaluation and guideline ofopinions for eventual testimony. In this section, we focus onthe limitations of self-reported subjective history withoutjudgment or mention as to whether an examinee might beconsciously distorting the history for secondary gain, mis-remembering pre, and post-injury events, or is simplyamnestic for facts surrounding a particular incident.

Being a plaintiff, defendant, or other interested party incivil litigation suggests an inherent bias that may place anemphasis on providing information that leads to the best pos-sible outcome of that legal proceeding. Examinee self-reportin forensic settings can be notoriously unreliable, with prob-lems that bring into question the accuracy of one’s subjectivehistory. Greiffenstein, Baker, and Johnson-Greene (2002) ex-amined agreement between self-reported and actual academicperformance with groups of litigants, including those withsevere traumatic brain injury and Blate postconcussionsyndrome^ (LPCS). They found that both groups inflated pastacademic performance significantly more than non-litigatingcontrols; however, the magnitude was greater with the LPCSgroup. The authors concluded as follows: BThese findingssupport previous studies which showed self report is not areliable basis for estimation of pre-injury cognitive status.Retrospective inflation may represent a response shift biasshaped by an adversarial context rather than a form ofmalingering^ (p. 202). Thus, analyzing past academic records,including transcripts, results of standardized testing, and evensupervisor ratings /employment records are helpful in corrob-orating reported history. In addition to estimating premorbidcognitive functioning, records often address pre-incident func-tioning across an array of psychiatric, neurologic, substanceabuse, and other areas and thus are vital to obtain (if theyexist), review, and incorporate within the overall evaluationcontext.

Lees Haley et al. (1997) studied the accuracy of self-reported histories in a large sample of personal injury litigantsin comparison to a non-litigating control group in five regionsthroughout the USA. Results showed that the litigants ratedtheir histories across various cognitive (concentration andmemory), psychiatric (depression, anxiety, and substanceuse), and physical (headache and fatigue) domains as well as

employment, academic areas, and Blife in general^ to be su-perior and more trouble free than the non-litigating controls.

Lees Haley et al. (1997) did not believe that malingeringcould fully account for the significant differences and offeredsocial pressures, cognitive dissonance, and other possible ex-planatory factors. Somewhat related (and discussed in detailin section 11 of this article) is the Bgood old days^ bias(Iverson, Lange, Brooks, & Rennison, 2010) in which foren-sic examinees tend to over-report pre-incident accomplish-ments and abilities.

That neuropsychologists often evaluate individuals wholegitimately have no memory or have impaired recall of acompensable traumatic event, such as the examinee with ahistory of brain injury including a loss of consciousness and/or post-traumatic amnesia in which no memories were stored,also dictates the necessity of reviewing records surroundingthe incident in question. This is especially important whentrying to objectively establish acute injury parameters thathelp grade TBI severity or the duration of loss of conscious-ness (LOC) for the victim of carbon monoxide poisoning. Insuch instances, paramedics, first responders, and emergencyphysicians who are trained to evaluate and document acuteinjury characteristics such as Glasgow Coma Scale scores,length of post traumatic amnesia, or carboxyhemoglobinlevels provide vital information that Bfill in the blank^ forthe time the examinee has no recall. Hospital or outpatientprovider records help trace an individual’s recovery (or lackthereof) and often contain neuroimaging reports, treatmentprovided and outcome, and cognitive evaluation findings.

It is time saving for the forensic neuropsychologist to havea checklist of these and all other recommended pre- and post-incident records to give to the referral source up front and as across check for the psychologist to ensure no primary sourceof records is being over-looked. Many civil personal injurycases can entail hundreds if not thousands of pages of records;therefore, developing an organizational system in which re-cords are indexed chronologically or according to provider orspecialty is recommended. However, relying exclusively onthe retaining attorney or claims adjuster to provide all or atleast key records in a case is presumptive as interested partiessometimes Bcherry pick^ records that support their side, with-holding key records harmful to their central premise(Schatman & Thoman, 2014). The forensic neuropsychologistshould therefore insist that all pre- and post-incident recordsbe provided including, if necessary, going directly to thesource document (e.g., requesting a vital discharge summarydirectly from the hospital). Awareness of a record with impor-tant implications that cannot be obtained should be noted inthe report to promote transparency.

Moreover, third party records can sometimes be misleadingand according to Cripe (2002) have significant limitationsincluding B…limited sampling; varied report writing styles;indirect methods; narrow focus; subjective biased

270 Psychol. Inj. and Law (2015) 8:265–280

interpretations; and lack of validation^ (p. 8). Thus, it may bedifficult to determine if the hospital psychologist’s definitionof Bdepression^ is the same as or close to the diagnosticcriteria used by the outpatient psychiatrist or IME physicianall of whom evaluated the same examinee and documentedBdepression.^ Psychologists sometimes rely on affidavits orquestionnaires that have been completed by an examinee’sspouse who may also be a party in the lawsuit. Again, theaccuracy of these documents must be scrutinized to rule outor establish potential response bias.

Finally, the lack of reliability in self reporting has evenbeen documented in non-litigating normal controls wherethere is no injury or apparent secondary gain. For instance,Otto et al. (1994) studied the effect of depression on memoryfunctioning. These authors concluded that their findings wereB…consistent with reports indicating that the self-report ofmemory complaints is linked to severity of depression but isnot significantly associated with actual memory performancein elderly subjects^ (p. 86). Thus, the forensic examinershould be reminded that individuals distort self-report inten-tionally perhaps to appear more impaired than they actuallyare and unknowingly as a function of conditions such as de-pression. As well, there are situations in which the examineegenuinely can’t remember or has impaired memory as a resultof loss/alteration of consciousness or other brain-relatedcondition.

Under-Utilization of Base Rates

The term base rate is defined as the frequency or prevalenceof a diagnosis, condition symptom, sign, or disorder within agiven population. For instance, the base rate of dementia in thegeneral population over age 85 years is approximately 20 %whereas the base rate of attention-deficit/hyperactivity disor-der in school age children is estimated as 3 to 5 % (AmericanPsychiatric Association, 1994). Base rates are fundamental inall of the medical sciences but especially important to theforensic neuropsychologist given the high number of teststypically administered. Base rates help inform the decision-making process and address the significance of a particulartest finding (McCaffrey, Palav, O’Bryant, & Labarge, 2003).Base rates are especially important in calculation of positivepredictive probability and negative predictive probability (seeLarrabee, 2012 for definitions and formulas of these classifi-cation statistics as well as sensitivity and specificity).However, there is reason to believe that neuropsychologistsunder-utilize or are unaware of base rates. Labarge,McCaffrey, and Brown (2003) surveyed 279 members of theNational Academy of Neuropsychology, posing various sce-narios in which participants had to answer questions related tocalculating sensitivity, specificity, and positive and negativepredictive values. Whereas a majority of neuropsychologists

correctly answered basic questions about sensitivity and spec-ificity, only 8.6 % were able to correctly compute the positivepredictive value question when it was presented in a probabilityformat; however, accuracy improved to 63 % when presentedin a frequency format.

Base rates are important for the neuropsychologist to considerin all conditions but especially important in the forensic evalua-tion of someone with known or suspectedMild Traumatic BrainInjury (MTBI). For instance, the base rate of malingering inplaintiffs with uncomplicated MTBI (negative neuro-imaging)has been estimated as high as 40 % (Larrabee, 2003).Moreover, it has been shown in this same population that thebase rate of cognitive symptoms beyond 12 months post-injuryis only approximately 5 % (Carroll et al., 2004; McCrea, 2008).Thus, if a forensic neuropsychologist is evaluating a plaintiffwho sustained an uncomplicated MTBI 4 years ago but stillpresents with numerous cognitive symptoms, it would be unwiseto not consider malingering and a host of other explanatoryfactors in the differential diagnosis. That is, the chance of malin-gering could be as high as 40 % in this hypothetical scenario butthere would be a much higher probability of factors other thanMTBI as the cause of persistent cognitive problems (e.g., pre-existing conditions and/or comorbid psychiatric or neurologicfactors would need to be ruled out).

Lees-Haley and Brown (1993) administered a 37-itemchecklist to a large sample of personal injury claimants under-going psychological evaluation for Bemotional distress.^Subjects, specifically excluded if they had any history ofTBI, seizures, toxic exposure, or other Bneuropsychologicalimpairment^, were compared to a control group of familypractice patients who presented with routine problems of sorethroat, respiratory problems, headache, flu, and hypertension.There was not an MTBI control group. The experimentalgroup (with no neurologic history) endorsed high numbersof neuropsychological (concentration, memory, word finding,and organization problems), psychological (anxiety, depres-sion, and loss of interest), and physical (headache, back pain,and fatigue) symptoms. There are two main conclusions fromthese and other studies: First, MTBI symptoms are non-specific and occur in high frequency in many clinical andnormal-control populations; it is therefore critical for the fo-rensic neuropsychologist to be aware of this base rate data.Second, relying extensively on MTBI or post-concussionchecklists or self report inventories likely places the neuropsy-chologist at risk of diagnostic error or faulty conclusions.

Paul Meehl famously pointed out that Bthe chief reason forour ignorance of the base rates is nothing more subtle than ourfailure to compute them^ (in Waller, Younce, Grove, & Faust,2006. p. 234). Our field now has extensive guides of base rateswith both clinical neuropsychology and general populations.McCaffrey et al. (2003) systematically documented symptombase rates for a wide array of medical (HIV/Aids, stroke, anddementia), psychiatric (learning disability, depression, and

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anxiety), and substance use/exposure (carbon monoxide, rec-reational drugs including marijuana, alcohol and cocaine, andpesticides/solvents) conditions. In 2006, McCaffrey, Bauer,O’Bryant, and Palav published Practitioner’s Guide toSymptom Base Rates in the General Population. Knowingthe base rates of the condition and symptoms in question willonly increase the forensic practitioner’s diagnostic and predic-tive accuracy.

Ignoring Normal Variance in Test Scores

Interpretation of neuropsychological test data is an acquiredskill that requires an extensive knowledge base and a clearunderstanding of the two issues: the likelihood of an abnormalscore, and the degree of covariance among cognitive domains,particularly the degree to which intelligence correlates withother domains. These issues have been thoroughly reviewedand clearly explained by Greiffenstein (2009) and Binder,Iverson, and Brooks (2009).

Determining whether a given number of scores reflectsneuropsychological impairment should take into account boththe level at which impairment is defined (e.g., 1, 1.5, or 2standard deviations below the mean or below an estimatedpremorbid level) and the number of tests that were adminis-tered. Of course, some pathognomonic signs may reveal im-pairment despite the overall number of tests not reaching thethreshold typically used for determining impairment. In defin-ing abnormal as more than one standard deviation below themean, it can be expected that in a battery of 20 measuresbetween 10 and 15 % of the scores will be impaired in anormal-control population (Heaton, Miller, Taylor, & Grant,2004). In a sample of 327 healthy adults, the use of demo-graphically adjusted scores resulted in even more abnormalscores (Schretlen, Testa, Winicki, Pearlson, & Gordon,2008). Therefore, it is a fallacy that all abnormal scores reflectbrain dysfunction and equally incorrect to say that all abnor-mal scores are acquired.

Although there are instances in which average scores re-flect a decline from a previously higher level, it is incorrect toautomatically assume that average scores in an individual ofabove average intelligence represent acquired deficits in everycase (Greiffenstein, 2009). Intelligence is not uniformly cor-related with other cognitive domains (Diaz-Asper, Schretlen,& Pearlson, 2004; Dodrill, 1997). Average performance mayresult from a variety of factors, including the psychometrics ofa given test (i.e., low ceiling), that are unrelated to cerebralimpairment in a person of above average intelligence.Therefore, the clinician looking to avoid biased interpretationof testing data would benefit from considering evidence thatsupports and disconfirms two scenarios. In the first scenario,the lowest scores in the profile are normal variance. In thesecond scenario, the lowest scores are reflective of true decline

from a previously higher baseline. Deliberate consideration ofboth scenarios may help to mitigate biased interpretation oftest scores.

Confirmation Bias

Confirmation bias is a psychological phenomenon wherebyan individual preferentially favors information that supportsan original hypothesis and ignores or dismisses data that maydisconfirm the favored hypothesis (Mendel et al., 2011;Nickerson, 1998). It is the process of seeking informationbased on a desired outcome. This bias has been recognizedin philosophy and psychology for decades and was describedas early as 1620 by Francis Bacon (Nickerson, 1998). It is notunique to medical professionals. In politics and debate, forexample, it is not uncommon for individuals to highlight factsthat are consistent with their positions while simultaneouslydismissing facts that may refute their position. In forensicscience, research has indicated that judging the similarity oftwo handwriting samples is directly affected by confirmationbias, and that confession of a crime can lead to collection ofevidence that fits the confession (Kukucka & Kassin, 2014).

Confirmatory information seeking is often not a consciousprocess, but even awareness of confirmation bias does notmake one immune to it (Mendel et al., 2011; Nickerson,1998). In addition to being aware of the bias itself, neuropsy-chologists must be continuously aware of their own decisionmaking processes (Gallagher, 2003). This section details waysto mitigate confirmation bias at three critical points in theneuropsychological evaluation: (1) the review of medical re-cords, (2) the selection of questions and use of answers in theclinical interview, and (3) interpretation of interview and test-ing data.

Medical records are commonly the first piece of evidencethat a neuropsychologist reviews in process of an evaluation.Even before embarking on the record review, clinicians areoften able to formulate a hypothesis about the nature of aninjury or illness based on other presenting information. At thatpoint in the diagnostic process, it is helpful to establish twocompeting hypotheses or at least remember the scientificmethod of establishing both a hypothesis and its null. If onlyone hypothesis is formulated, confirmation bias can arise outof a tendency to seek information that confirms the one hy-pothesis (Nickerson, 1998). This may occur in part because ofa preference for reducing the possibility that the original hy-pothesis was wrong (i.e., Berror reduction^) as one proceedsthrough the diagnostic process (Friedrich, 1993).Confirmation bias occurs more frequently in settings wherehypotheses are considered sequentially as opposed to simul-taneously (Jonas, Schultz-Hardt, Frey, & Thelen, 2001). Inaddition, research on biased decision making indicates thatafter a person commits to a single hypothesis, there is typically

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preference for confirmatory evidence because disconfirmatoryevidence results in too much cognitive dissonance (e.g., Jonaset al., 2001). Perhaps for this reason, Borum, Otto, andGolding (1993) recommended a deliberate attempt to searchfor disconfirmatory evidence to interrupt the pattern of confir-matory searching (see also, Wedding & Faust, 1989).

Upon embarking on amedical record review, it is importantto keep in mind that information gathered early in the diag-nostic process tends to have more weight than informationgathered later (Nickerson, 1998). Given this primacy effect,clinicians wishing to reduce confirmation bias will seek toreview the most objective sources of information first(Wedding & Faust, 1989). For example, in a case of traumaticbrain injury, this might be a preferential early review of aparamedic’s report and emergency department records.

The next step in the diagnostic process is often the clinicalinterview. In the effort to avoid confirmation bias and prema-ture commitment to a preliminary diagnosis, the interview isperhaps the most precarious point of the diagnostic process. Ifa bias is already brewing, the clinician can create diagnosismomentum in the interview by posing only questions that willconfirm a specific hypothesis. This problem can becompounded by an acquiescence bias on the part of the inter-viewee who may be inclined to answer affirmatively. To avoidthis situation, it can be helpful to begin a diagnostic interviewas transparently as possible by saying something like BI amgoing to ask about a number of symptoms not all of which willfit your experience.^ Interview questions could be deliberatelybalanced between questions that are designed to enhance andlower confidence in a specific hypothesis. The clinician whotends to interview in a manner that favors Byes^ responsesmay have selected a series of questions in order to confirm ahypothesis.

The nonbiased use of objective neuropsychological testingdata is easier when a clinician has not prematurely committedto diagnosis. Committing to an expected level of impairmentor neurobehavioral syndrome before seeing the test scores is arisk factor for confirmation bias. It also increases the risk ofperceiving Billusory correlations^ (Chapman & Chapman,1969) between test scores and patient behavior or that injuryA must be associated with symptom B. It is important tomaintain competing hypotheses all the way through the eval-uation, including the test data review. If cognitive impairmentis found and a confirmation bias is at work, the etiology of thecognitive impairment will be automatically biased. In otherwords, the clinician who seeks to find cognitive impairmentwill, due to a confirmation bias, inevitably try to find cognitiveimpairment. Consider the case of MTBI in which a patientshows evidence of attention impairment on neuropsychologi-cal testing 12 months post injury. For the neuropsychologistwho has fallen victim to confirmation bias, he or she may seekto ascribe the attention impairment to MTBI while ignoringpotentially conflicting or disconfirming information. A

second contrasting example would be a patient who is3 months into her recovery from MTBI who also has a pre-existing anxiety disorder and evidences attentional deficits onformal testing. The neuropsychologist who has developed abias that attention problems are entirely related to the pre-existing anxiety disorder could erroneously exclude any con-tribution of the MTBI. Specifically, the biased neuropsychol-ogist in this example would unknowingly or deliberately re-view records, ask interview questions, and interpret test resultsin such a manner as to seek information that confirms theanxiety causation while downplaying or ignoring contribu-tions from the MTBI. In short, there is a need to consider bothfactors as MTBI can certainly produce acute attentional prob-lems and concurrent anxiety could exacerbate attentional andother cognitive problems.

Personal and Political Bias

In the voir dire process of jury selection, attorneys on bothsides of a civil dispute question potential jurors about an arrayof attitudes, stereotypes, and life experiences to determine ifbias exists in order to exclude jurors thought unable to beimpartial in evaluating the case at hand. Although forensicneuropsychologists may undergo voir dire on the stand byattorneys in attempts to qualify or disqualify them, this selec-tion process does not occur up front for experts who are oftenretained on factors as basic as willingness to take a case, avail-ability to meet deadlines, costs, and perhaps recommendationsof a legal colleague. It is then during the expert’s deposition orcross examination that biases can be probed and exposed ifthey exist.

Like the general public, neuropsychologists and their fam-ily and friends can be the victim of various adverse life expe-riences that can shape attitudes and contribute to unconsciousstereotyping or frank bias. For instance, the expert or his/herfamily member(s) may have been involved in a motor vehicleor other accident or be the victim of crime, malpractice, ornegligence through no fault of their own. Careful self-examination is required here to insure the expert is not biasedby such an event or trying to champion a cause.

Potentially more pervasive and not as obvious as thesemajor life experiences are political beliefs that vary from slightaffiliation with one political party to a full subscription to anideology associated with another party. As of this writing, weare 15 months away from the next presidential election andalready bombarded in the print, electronic, and television/radio media with highly polarizing news and advertisementspertaining to candidates’ views on foreign and domestic pol-icy, the BPatient Protection and Affordable Care Act,^ the roleof government vs. the private sector in health care insuranceand dozens of other hot topic issues. Equally prevalent in theAmerican two-party system are subtle and obvious political

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views about individual responsibility of citizens, the role andneed (if any) of various social Bsafety nets^ and governmentassistance programs, gun rights, safety and violence, tort re-form, Brun-away^ jury verdicts, and so on. However, many ofthe plaintiffs that the forensic neuropsychologist evaluates aresome of the very individuals that are often the direct andindirect subject of strong political messages or ideologies as-sociated with one political party or the other (e.g., the victimor perpetrator of gun violence or motor vehicle accident, theperson with no insurance vs. a defendant with Bdeeppockets^). In addition to the potential personal and politicalbiases discussed in this section, Ruff (2009) urged the forensicexaminer to be aware of Bcountertransference issues,^ that is,examinee characteristics such as age, gender, attractiveness,ethnicity, and socioeconomic status that could elicit an emo-tion or reaction in the neuropsychologist that somehow effectattitudes and expert opinions. There is no guarantee that theexpert’s life experiences, political views or countertransfer-ence will or will not shape his/her forensic opinions but vig-ilance, careful self-reflection, and various Bpracticeguidelines^ as articulated by Ruff (2009) are required to pro-mote impartiality.

Group Attribution Error

Group attribution error refers to the belief that an individual’straits are representative of a whole group (Allison & Messick,1985). The understanding of group attribution error has beenat the core of the social psychology research on racism andstereotype persistence for many years. Issues of ethnoculturaldiversity in neuropsychological assessment are beyond thescope of this article, but have been reviewed elsewhere (e.g.,Archives of Clinical Neuropsychology 2007 special edition oncultural diversity). In our opinion, the applications of groupattribution error can extend to diagnostic categories as well asculture and ethnicity. The same attribution bias can occur inthe clinician who develops overly rigid expectations about theways individuals with certain illnesses should behave and/orperform on neuropsychological tests. This type of bias may bepresent in the clinician who thinks that everyone withAlzheimer’s disease should present in a certain manner, oreveryone with injury history of MTBI should have a certainconstellation of symptoms, or everyonewith fibromyalgia hasa somatoform disorder. The conscientious neuropsychologistcan attempt to mitigate this bias by first examining his/herpersonal practice to identify which individual traits or diag-nostic categories are most likely to be overgeneralized. It canthen be helpful to carefully analyze the interview and testingdata from those cases to make sure that symptoms are notbeing dismissed because they are nonconforming to an ex-pected constellation of symptoms.

Diagnosis Momentum

Research has estimated that 75 % of clinician diagnostic fail-ures can be attributed to cognitive error by the clinician, whichcan stem from a variety of factors, such as insufficient knowl-edge, inadequate data obtainment and synthesizing, and/orfaulty data verification (Thammasitboon & Cutrer, 2013). Inaddition to the cognitive errors described previously, diagno-sis momentum bias is equally relevant and warrants consider-ation. This bias is defined as the tendency for an opinion orworking diagnosis to become almost certain as it is passedfrom person to person, thereby suppressing further evaluation(Croskerry, 2002). In other words, clinicians may prematurelyand/or inaccurately assign a diagnosis early, and then thisdiagnosis gains momentum when subsequent clinicians ac-cept the initial diagnosis, with no consideration of differentialdiagnoses. Contributions from the field of cognitive psychol-ogy have led to this bias gaining increased attention in theliterature, largely in the medical and emergency departmentsettings, though with clear relevance for forensic neuropsy-chological practice.

It is essential that clinicians and forensic neuropsycholo-gists are vigilant to diagnosis momentum bias as the founda-tions for this bias begins as soon as an individual is given adiagnosis and is often an unconscious or unintended process(Vick, Estrada, & Rodriguez, 2013). In an inpatient setting, forinstance, a patient may be labeled as Bdemented^ afterevidencing moderate difficulty on a Mini-mental StateExam. If care is not taken, this label, applied presumably byan inpatient treatment team and therefore carrying the weightof a Bteam^ diagnosis, can follow a patient and have long-lasting implications for treatment, even if further assessmentand diagnostic verification have not been attempted. This ex-ample illustrates the notion that diagnosis momentum bias isan example of a systemic error, which in combination withcognitive biases, can lead to diagnostic errors in all fields ofclinical practice.

The negative consequences of diagnosis momentum biasextend into the forensic setting. For instance, in a recent legalcase in which one of the authors was involved, a seeminglywell-intended primary care physician (PCP) diagnosed MTBIand made a number of referrals to other treatment providerssuch as speech/cognitive therapy, psychiatry, and psychology.Throughout the records, all of these clinicians used the samediagnosis. Approximately 3 years later when this same PCPwas deposed and asked the basis of her diagnosis, she testifiedthat her patient was involved in a moderate speed automobileaccident and sustained a small laceration to his forehead.Thus, she concluded, it would be reasonable to assume hesustained an MTBI based on these and other factors. Shewas next confronted with records documenting no loss oralteration of consciousness, a GCS score of 15, and an affida-vit from a witness who stated he had an accurate conversation

274 Psychol. Inj. and Law (2015) 8:265–280

with the patient at the scene about a sporting event they hadeach happened to watch on television the prior night. The PCPeventually conceded that she did not use any specific MTBIdiagnostic criteria and based the diagnosis exclusively onwhat her patient told her. Similarly, when each treatment pro-vider was asked how they arrived at the MTBI diagnosis, theyall testified that they simply used the referring physician’sdiagnosis without independent verification. This exampleagain highlights the systemic and individual contributions thatcan perpetuate this bias.

Diagnosis momentum can also have significant conse-quences when malingering is the diagnosis. In another recentcase, a forensic neuropsychologist hired by the defense wasevaluating a plaintiff who had been labeled malingering inprior evaluations. The expert was vaguely aware of the spe-cific indicia of malingering in the past and was also frequentlyreminded of these by the retaining attorney. After closelyreviewing the prior reports from both medical and psycholog-ical experts, it became clear that malingering was only com-prehensively evaluated in the first evaluation, and similar tothe aforementioned example, subsequent evaluators seemedto concur with the diagnosis with minimal independent veri-fication. Indeed, treatment records at a rehabilitation facilitycited one of the prior evaluations (not the first) in opining thatintervention was Bnot necessary due to the patient’s feignedsymptomatology.^ Although it is possible the plaintiff wasmalingering across all evaluations, it is equally possible thatthe pejorative nature of this label instantly cast doubt and biasin subsequent evaluators. Diagnosis momentum in this exam-ple can lead to individuals not receiving treatment that is gen-uinely indicated and can have significant legal ramifications.

It is important to recognize that cognitive biases are inevi-table and often occur without intention. Therefore, forensicneuropsychologists must take proactive steps to mitigate therisk of this bias. Understanding the nature of cognitive biasesand their prevalence is a recommended fundamental step todecreasing risk. According to Kahneman (2003), a dual-process model unifies many theories of decision-making andcan help provide insight into how clinicians think, reason, andjudge efficiently in the diagnostic process. Although it is out-side the scope of this article to describe this theory in detail,applying Kahneman’s (2003) model, clinicians rely on twomodes of decision making, BSystem 1^ and BSystem 2.^System 1 is comprised largely of non-analytical thinking andis characterized as intuitive, tacit, and experiential and may becomprised of pattern recognition. Thus, in a neuropsycholog-ical evaluation, once a combination of clinical features is rec-ognized, System 1 mode is enacted and can result in a rapiddiagnosis. However, this method alone is vulnerable to errorsand bias. If the diagnostic pattern is not easily recognized, theSystem 2 mode, or analytical thinking, is then activated. TheSystem 2 mode is described as slow, deliberate, conscious,and effortful reasoning that is often effective but not as

efficient, the latter of which can be particularly detrimentalin critical diagnostic conditions where time is of the essence.

Utilizing Kahneman’s (2003) theory as a way to understandclinical decision making, it follows that methods to protectagainst biases will target both System 1 and System 2.Researchers have proposed several ways in which to mitigatecognitive biases, including diagnosis momentum, in generaland in relation to these decision-making systems (e.g.,Croskerry, 2002; Thammasitboon & Cutrer, 2013). Thoughmany of these interventions are primarily suggestions due toa lack of proven efficacy in the literature, they warrant con-sideration as the alternative of inaction in this area is unaccept-able. Below is a subset of strategies that can be employed toaddress diagnosis momentum bias as well as other cognitivebiases, many of which overlap.

In general, strategies to protect against cognitive bias en-compass both a focus on increasing clinician expertise and onavoiding inherent cognitive errors. The competent forensicneuropsychologist must keep in mind the importance ofreviewing all available records, including diagnoses, with ahigh degree of scrutiny and careful attention to diagnosis mo-mentum. Care should be taken to assess the validity of previ-ously rendered diagnoses, after considering all available infor-mation. To do this, the onus is on the neuropsychologist tohave sufficient understanding about any/all relevant diagnoseswhich he/she is considering.

Understanding that forensic neuropsychologists typicallyreview many records prior to an evaluation and therefore areprivy to existing diagnoses, it is prudent for them to engage ina hypothesis-driven approach to rendering his/her own diag-noses, which must involve carefully considering differentialdiagnoses. In other words, asking BWhat else might this be?^is helpful, and the pause inherent in this questioning can acti-vate the aforementioned System 2 to be used in conjunctionwith System 1 (Croskerry, 2003). A useful exercise is to con-sider and practice how one would explain to a trier-of-factwhy a particular diagnosis would or would not be consideredor ruled out. Obtaining peer consult and feedback can be help-ful with this exercise.

Some research has posited that metacognition, orBthinking about thinking,^ should be utilized as a meth-od to counteract cognitive biases by increasing aware-ness of one’s own thought processes and clinical rea-soning (Croskerry, 2003; Groopman & Hartzband,2011). Metacognition may allow a forensic neuropsy-chologist to reflect upon his/her decision-making skillsand sharpen the ability to identify and prevent cognitivebiases. Croskerry (2003) described five features ofmetacognition that can improve clinical reasoning inthe context of System 1: (1) awareness of requirementsof learning process, (2) recognition of limitations ofmemory, (3) ability to appreciate perspective, (4) capac-ity for self-critique, and (5) ability to select strategies.

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Strategies to mitigate diagnosis momentum bias as it mayimpact System 2 include ensuring the use of evidence-basedpractices and normative decision making, obtaining targetedtraining on common errors identified in practice settings andemploying metacognition (Croskerry, 2003). RegardingSystem 2, reflection (e.g., upon one’s work or comfort levelwith a diagnosis) can also be useful to improve a forensicneuropsychologist’s self-awareness as well as his/her overallreasoning process (Croskerry & Nimmo, 2011).

Good Old Days Bias

As this article has highlighted, there are multiple factors thatcan impact the validity, outcome, and efficacy of a forensicneuropsychological evaluation. Most of the previouslydiscussed factors involve the impact of the cognitive biasesof the evaluator. The Bgood old days^ bias is similar to self-report bias, in that it is held by the individual being evaluated.It can impact an individual’s retrospective perception andreporting of symptoms. This bias is included in this paperbecause it is imperative for forensic neuropsychologists toconsider when conducting evaluations, particularly with thosewho have, or may have, sustained an MTBI. Research (e.g.,Dikmen, Machamer, & Temkin, 2001; McCrea et al., 2009)has indicated that recovery from an MTBI is measured byexamining the resolution of post-concussive symptoms backto premorbid levels. The Bgood old days^ bias is the tendencyto view oneself as healthier or higher functioning in the past,or to underestimate symptoms, prior to an injury. Indeed, re-search has shown that patients with back injuries, generaltrauma, and those who have sustained MTBIs, including chil-dren, tend to report fewer pre-injury symptoms than the baserate of symptoms in healthy adult and pediatric samples, andthese patients tend to overestimate the actual degree of changefrom pre-injury (Brooks et al., 2013; Davis, 2002; Gunstad &Suhr, 2001, 2004; Hilsabeck, Gouvier, & Bolter, 1998;Mittenberg, DiGiulio, Perrin, & Bass, 1992). That is, individ-uals have a tendency to misperceive or misrepresent their pre-injury functioning as better than the average person, whichthen negatively impacts their perception of current problems,recovery from their injury, and ability to return to work (e.g.,Iverson et al., 2010). This finding is further complicated byone’s involvement in personal injury civil litigation (e.g., seeabove reference to Lees-Haley et al., 1997).

The research into this complex area of science is ongoing,with interesting and innovative findings driving further re-search. Recently, noteworthy is the first study to prospectivelyevaluate the Bgood-old-days^ bias in different domains ofpost-concussion symptoms (PCS) in patients with a historyof MTBI (Yang et al., 2014). Yang et al. found additionalsupport that the Bgood-old-days^ bias is seen in patients witha history of MTBI by 1-month post-injury, but that this

response bias may diminish by 3-month post-injury. In thisstudy, PCS was subdivided into physical, cognitive, and emo-tional domains, and results found that the Bgood-old-days^bias presented differently in these domains. First, the Bgood-old-days^ bias was prominent in the physical and cognitivedomains but not in the emotional domain. This finding maysuggest that patients with MTBI histories overestimate theirpre-injury physical and cognitive abilities rather than emotion-al reactions such as depression and anxiety, possibly due to thefact that medical symptoms are easily viewed as indicators ofmedical illness. Yang et al. proposed that patients with MTBIhistories may more readily recognize the pre-injury supernor-mal status of physical and cognitive abilities versus emotionalsymptoms, and thus, it is possible that such emotions may notbe subjectively perceived as a Bsymptom^ during evaluation.Results also found that the Bgood-old days^ bias involvingcognitive PCS symptoms tended to diminish by 3-monthpost-injury. In fact, the Bgood old days^ bias seemed to persistat a consistent rate only with the physical PCS symptoms.

Yang et al. (2014) hypothesized that this finding couldsuggest that the Bgood-old-days^ bias may be a dynamic psy-chological process that occurs after one sustains a mild injury.If this is true, the authors suggested that it is important tocontinuously monitor patients’ symptom reporting in clinicalsettings because of the possibility that the Bgood-old-days^bias can evolve with time. Awareness of the specific factorsthat can contribute to this bias can potentially inform the cre-ation of targeted psychological interventions to address PCS.

To mitigate the risk of obtaining faulty data and/or makingproblematic inferences due to the Bgood old days^ bias ofthose being evaluated, forensic neuropsychologists must beaware of the continuously evolving research, and ongoingcontroversy, in this area of practice. Several of the aforemen-tioned biases (e.g., self-report bias and underutilization of baserates) are particularly relevant. Knowledge is crucial from thestate of the science to the accurate assessment of thepremorbid and postmorbid functioning of the individual.With respect to the latter, it is prudent for forensic neuropsy-chologists to obtain as much collateral information as avail-able that can help provide insight into the examinee’s pre- andpost-injury states. Reliance on self-report alone is insufficient.It is also important for forensic neuropsychologists to beaware of base rates, so that they can have a context in whichto interpret the individual’s current symptoms. For example,neuropsychologists unfamiliar with base rates may be partic-ularly vulnerable to overpathologizing normal variance. It iseasy to see how this can be further complicated if a forensicneuropsychologist engages in confirmation bias from the on-set of the evaluation. In essence, evaluation of an individual’ssymptoms, and his/her perceptions of symptoms post-injury,requires thoughtful, pro-active consideration of many factorsto increase the chance of a valid assessment, which is of ut-most necessity in civil litigation.

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Overconfidence

Bias exists in spite of excellent training, professional suc-cesses, and desire to be bias free. Bias also is unaffected byyears of experience in practice and is therefore equally likelyto occur in experienced and early career psychologists (Grove,Zald, Lebow, Snitz, & Nelson, 2000; Sladeczek, Dumont,Martel, & Karagiannakis, 2006). The overconfidence bias asit applies to neuropsychology is most related to the accuracyor precision of one’s diagnostic capabilities (Harvey, 1997).This bias characterizes the neuropsychologist who is 100 %certain that they know Bthe truth^, perhaps as a consequenceof the confirmatory bias or diagnosis momentum problemsthat are described in other sections of this article. It can leadto diagnostic errors because of an inability to consider com-peting hypotheses. Therefore, deliberate consideration of twocompeting hypotheses is as essential in reducing overconfi-dence as it is in reducing confirmation bias. Other ways tomitigate overconfidence involve requesting periodic peer re-views of forensic reports, and being aware of one’s own lim-itations in training and experience, including a lack of con-tinuing education in forensic neuropsychology.

Discussion

To be biased is to be human, and neuropsychologists are noexception. But striving to reduce, manage, or otherwise con-trol the impact of those biases on one’s forensic services is anessential obligation of neuropsychologists. The above list ofbiases is not exhaustive (dozens more exist) nor mutuallyexclusive. For instance, the Bgood old days bias^ is a type ofBself report bias, and Bdiagnosis momentum bias^ is a form ofBconfirmatory bias.^ Even non-forensic psychologists aresubject to myriad biases that effect their decision makingand judgment. Then, when an adversarial setting with highstakes and heightened scrutiny is introduced in the forensicarena, the potential for cognitive biases and diagnostic errorsonly increases. In adversarial systems, two equally competentneuropsychologists can and often do disagree, arguing forinstance that the opposing expert’s written report or method-ology suggests confirmation, financial, or referral bias or rep-resents overconfidence. Whereas the cross examination pro-cess provides certain checks on revealing bias, jurisdictionalethics, and licensing boards rarely get involved except in casesof egregious ethical violations; for instance, the forensic neu-ropsychologist who provides expert opinions to Bprove^ afamily member’s damages or facilitate their acquittal of analleged crime, or the expert who engages in an unethical con-tingency fee scheme with bonuses and incentives. Ultimately,however, it is up to the individual professional to monitorbiases and take appropriate steps to reduce and eliminatethem.

Although the neuropsychologist has to be attentive tobiases throughout the entire expert witness process, we concurwith Greiffenstein and Kaufmann (2012) that following theresolution of a case is the ideal time to engage in variousdebiasing techniques and what Brodsky (1999) terms anBintegrity check.^ When the stress and time requirements ofa legal case are over, the expert can turn his/her attention toself -examination of bias. We have described specific ways tomitigate each of the one dozen biases described above: Somemitigation steps are straightforward and dichotomous (the ex-pert simply does not accept a forensic case on contingency feearrangements or provide forensic opinions regarding currentpatients). However, a majority of these biases vary in subjec-tivity, and experts can both knowingly and unconsciously besubject to committing some or many of them.

Borum et al. (1993) listed various clinical examples withBcorrective measures^ to improve clinical judgment anddecision making in forensic evaluations. Martelli et al.(2003) offered 14 recommendations to promote objectivityand ethical conduct in medicolegal settings (e.g., BEnsureagainst excessive black and white findings. Recognize thelimitations of scientific, medical and neuropsychologicalopinion, fewer findings are black or white and attributable toa single event.^ P. 34). Sweet and Moulthrop (1999) createdtwo sets of BSelf-examination questions as a means of identi-fying bias in adversarial assessments.^ Their heuristic ap-proach was discussed from a general standpoint and then re-garding the forensic neuropsychology report. Lees-Haley(1999) provided follow up commentary on these debiasingprocedures, concluding BSweet and Moulthrop’s articleshould be viewed as an excellent starting point for furtherdialogue. Now we need critical review of the debiasing pro-cedures and process for testing and peer reviewing theireffectiveness^ (p. 47). Unfortunately, the intervening 16 yearshas seen a paucity of research on the latter recommendation.

Martinez (2014) appropriately urged the early-career foren-sic psychologist to develop Bgood habits^ early on regardingthe identification and management of potential bias. However,some neuropsychologists enter the forensic/adversarial arenamid to late career. Knowledge is key here and may be obtain-ed, for instance, via continuing education, clinical supervision,peer consultation, and experience. Developing a small peergroup in which two forensic experts review each other’s re-ports and deposition/trial transcripts especially for a settledcase that posed unusual challenges can help raise awarenessof bias(es) and develop steps to mitigate. Finally, one couldmodify Appendix 1 and utilize it as a simple check-list ofthese one dozen biases with notation of those areas (if any)that proved problematic or the subject of difficult-to-answercross examination questions. For instance, has the expert ac-cepted too many referrals from a particular law firm notoriousfor withholding records or a difficult-to-work with attorney;has the expert failed to consider high or low base rates of the

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subject condition; did a political attitude, group attributionerror, or stereotype interfere with objectivity; or has the expertrelied too heavily on self report and failed to obtain a keyrecord that he/she was confronted with on the witness stand?The list is seemingly endless and actions from an honest self-appraisal can guide ways to reduce bias in one’s practice, andhelp revise or fine tune methodology to insure the bias doesnot happen again or minimally, is controlled as much aspossible.

Compliance with Ethical Standards

Conflict of Interest The authors declare that they have no competinginterests.

Appendix 1

12 Sources of Bias in Forensic Neuropsychology1. Role bias: Conflating clinical and forensic roles2. Financial/Payment bias3. Referral source bias (and retaining attorney pressure)4. Self report bias (Need for corroborative data)5. Under-utilization of base rates6. Ignoring normal variance in test scores7. Confirmation bias8. Personal and political bias9. Group attribution error10. Diagnosis momentum11. Good old days bias12. Overconfidence

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