We integrate multiple domains of psychological science to identify, better understand, and manage the effects of subtle but powerful biases in forensic mental health assessment. This topic is ripe for discussion, as research evidence that challenges our objectivity and credibility garners increased attention both within and outside of psychology. We begin by defining bias and provide rich examples from the judgment and decision making literature as they might apply to forensic assessment tasks. The cognitive biases we review can help us explain common problems in interpretation and judgment that confront forensic examiners. This leads us to ask (and attempt to answer) how we might use what we know about bias in forensic clinicians’ judgment to reduce its negative effects.

A qualitative study with 20 board-certified forensic psychologists was followed up by a mail survey of 351 forensic psychologists in this mixed-methods investigation of examiner bias awareness and strategies used to debias forensic judgments. Rich qualitative data emerged about awareness of bias, specific biasing situations that recur in forensic evaluations, and potential debiasing strategies. The continuum of bias awareness in forensic evaluators mapped cogently onto the “stages of change” model. Evaluators perceived themselves as less vulnerable to bias than their colleagues, consistent with the phenomenon called the “bias blind spot.” Recurring situations that posed challenges for forensic clinicians included disliking or feeling sympathy for the defendant, disgust or anger toward the offense, limited cultural competency, preexisting values, colleagues’ influences, and protecting referral streams. Twenty-five debiasing strategies emerged in the qualitative study, all but one of which rated as highly useful in the quantitative survey. Some of those strategies are consistent with empirical evidence about their effectiveness, but others have been shown to be ineffective. We identified which strategies do not help, focused on promising strategies with empirical support, discussed additional promising strategies not mentioned by participants, and described new strategies generated by these participants that have not yet been subjected to empirical examination. Finally, debiasing strategies were considered with respect to future directions for research and forensic practice.

This survey of 206 forensic psychologists tested the “filtering” effects of preexisting expert attitudes in adversarial proceedings. Results confirmed the hypothesis that evaluator attitudes toward capital punishment influence willingness to accept capital case referrals from particular adversarial parties. Stronger death penalty opposition was associated with higher willingness to conduct evaluations for the defense and higher likelihood of rejecting referrals from all sources Conversely, stronger support was associated with higher willingness to be involved in capital cases generally, regardless of referral source. The findings raise the specter of skewed evaluator involvement in capital evaluations, where evaluators willing to do capital casework may have stronger capital punishment support than evaluators who opt out, and evaluators with strong opposition may work selectively for the defense. The results may provide a partial explanation for the “allegiance effect” in adversarial legal settings such that preexisting attitudes may contribute to partisan participation through a self-selection process.

Bias, or systematic influences that create errors in judgment, can affect psychological evaluations in ways that lead to erroneous diagnoses and opinions. Although these errors can have especially serious consequences in the criminal justice system, little research has addressed forensic psychologists’ awareness of well-known cognitive biases and debiasing strategies. We conducted a national survey with a sample of 120 randomly-selected licensed psychologists with forensic interests to examine a) their familiarity with and understanding of cognitive biases, b) their self-reported strategies to mitigate bias, and c) the relation of a and b to psychologists’ cognitive reflection abilities. Most psychologists reported familiarity with well-known biases and distinguished these from sham biases, and reported using research-identified strategies but not fictional/sham strategies. However, some psychologists reported little familiarity with actual biases, endorsed sham biases as real, failed to recognize effective bias mitigation strategies, and endorsed ineffective bias mitigation strategies. Furthermore, nearly everyone endorsed introspection (a strategy known to be ineffective) as an effective bias mitigation strategy. Cognitive reflection abilities were systematically related to error, such that stronger cognitive reflection was associated with less endorsement of sham biases.

This project began as an attempt to develop systematic, measurable indicators of bias in written forensic mental health evaluations focused on the issue of insanity. Although forensic clinicians observed in this study did vary systematically in their report-writing behaviors on several of the indicators of interest, the data are most useful in demonstrating how and why bias is hard to ferret out. Naturalistic data was used in this project (i.e., 122 real forensic insanity reports), which in some ways is a strength. However, given the nature of bias and the problem of inferring whether a particular judgment is biased, naturalistic data also made arriving at conclusions about bias difficult. This paper describes the nature of bias – including why it is a special problem in insanity evaluations – and why it is hard to study and document. It details the efforts made in an attempt to find systematic indicators of potential bias, and how this effort was successful in part but also how and why it failed. The lessons these efforts yield for future research are described. We close with a discussion of the limitations of this study and future directions for work in this area.

Since its debut over a century ago, forensic psychology has matured into a formally recognized specialty area of psychology with its own set of ethical guidelines; however, a consensual definition of forensic psychology remains elusive. After describing the field’s historical and current struggles to define itself, two ethical issues are discussed that are especially applicable to psychology in legal contexts. The first is the critical differences between serving in therapeutic versus forensic roles and the associated ethical obligation to refrain from serving in both roles in the same case. Despite the terminology used in the literature, treatment in forensic contexts can be ethically appropriate. This chapter considers the current state of the literature regarding treatment in forensic contexts and suggests that this is likely to be an area of future growth for the field. The second ethical issue discussed in this chapter is the insidious effect of the adversarial process on psychologists’ objectivity in forensic contexts, termed “forensic identification” or “adversarial allegiance.” The forensic ethical guidelines affirm the primacy of this issue in forensic contexts, as evidenced by addressing it in the first two published guidelines. However, field and experimental evidence suggest psychologists have a challenging (if not impossible) task in avoiding partiality in adversarial forensic contexts. The chapter ends by briefly considering the methods psychologist might use in an effort to reduce partiality and by recognizing more research is needed to identify what else psychologists can do to strive to uphold the ethical guidelines in this regard.

This chapter integrates from cognitive neuroscience, cognitive psychology, and social psychology the basic science of bias in human judgment as relevant to judgments and decisions by forensic mental health professionals. Forensic mental health professionals help courts make decisions in cases when some question of psychology pertains to the legal issue, such as in insanity cases, child custody hearings, and psychological injuries in civil suits. The legal system itself and many people involved, such as jurors, assume mental health experts are “objective” and untainted by bias. However, basic psychological science from several branches of the discipline suggest the law’s assumption about experts’ protection from bias is wrong. Indeed, several empirical studies now show clear evidence of (unintentional) bias in forensic mental health experts’ judgments and decisions. In this chapter, we explain the science of how and why human judgments are susceptible to various kinds of bias. We describe dual-process theories from cognitive neuroscience, cognitive psychology, and social psychology that can help explain these biases. We review the empirical evidence to date specifically about cognitive and social psychological biases in forensic mental health judgments, weaving in related literature about biases in other types of expert judgment, with hypotheses about how forensic experts are likely affected by these biases. We close with a discussion of directions for future research and practice.