What Examples of Junk Science Most Commonly Appear in Forensic Psychological Assessments, and How Can Forensic Psychologists Avoid Them?

To avoid junk science, forensic psychologists must first understand what differentiates it from bona fide scientific practice. Pseudoscience typically fails to meet the standards of scientific inquiry in several critical ways:

• Avoiding Falsifiable Claims: A hallmark of a real scientific process is that its claims can be proven wrong. Junk science often employs ad hoc maneuvers, or "escape hatches," to explain away negative results.
• No Peer Review: Prudently done science leverages the impartial scrutiny of outside experts to safeguard against mistakes, blind spots, groupthink, and the like. Many junk science practices bypass this system of checks and balances, preferring to evaluate their own claims in isolation or to make blanket claims of bias against standard peer review practices.
• Refusal to Evolve: While legitimate science evolves as incorrect claims are weeded out, junk science tends toward intellectual stagnation, where faulty claims persist for decades despite contradictory evidence.
• Overreliance on Anecdotes: Pseudoscience often relies heavily on personal testimonials, circumstantial evidence, or hunches, rather than systematic, reproducible data.
• Extravagant Claims: Advocates of junk science frequently make extreme assertions of accuracy, such as near 100%, that far outstrip actual scientific evidence. These claims are often made in an attempt to show the superiority of these junk science methods over more established science, but can in fact be a tell that something is amiss.

Research suggests that one-third of psychological tests used in US court proceedings are not generally accepted by experts in the field. Furthermore, only 40% of these tools receive favorable reviews of their technical properties in leading sources. Several issues can make forensic psychologists susceptible to suspect claims:

• The Representativeness Heuristic

As the forensic psychologist gains experience, they may naturally start mentally sorting cases into types. This tendency can lead them astray when an assessment feels similar to another, even if those similarities are ultimately superficial. The representativeness heuristic can cause forensic psychologists to ignore or downplay base rates, aligning their assessment more with a small number of similar cases from their own experience over a more representative sample from the general population.  

• Contrast effects

Because forensic psychologists are immersed in case work, it is only natural to compare the relative attributes of these cases to each other, particularly the most recent ones. This comparison can introduce contrast effects, in which an assessment is influenced by how it compares to those in the forensic psychologist’s available memory. Contrast effects can detach assessments from their core principles and standards.

• Anchoring

Anchoring refers to the phenomenon in which first impressions and even unrelated information can impact an assessment. A forensic psychologist’s initial impressions of a case may anchor them toward that first notion, leading to confirmation bias. 

Unsubstantiated Assessment Tools and Methods: Certain projective tests like the Rorschach inkblot test have been used to make definitive claims about personality or psychopathology, which are not supported by robust studies. Administrators may compound the problem by using unstandardized scoring systems or making interpretations that go beyond what the research supports. Similarly, some practitioners rely on figure drawings or other projective measures that lack robust empirical validation for forensic purposes.

Intuition-Based Memory and Credibility Assessment: Evaluators can sometimes trust their own judgment more than the research literature, particularly when looking to detect lying or deception through behavioral observation alone. Some practitioners have also made unfounded claims about being able to determine whether abuse occurred based on behavioral indicators alone, and about techniques that can reliably recover repressed memories.

Risk Assessment Issues: It is poor practice to use unvalidated risk assessment instruments or clinical judgment alone without actuarial tools. Predictions about future risk based on clinical intuition, or using outdated assessment tools that haven’t been validated on relevant populations, can lead to unreliable conclusions. Actuarial tools consistently outperform unstructured clinical intuition in predicting recidivism.

Diagnostic Overreach: Evaluators can be tempted to make claims with insufficient evaluation time or data, including diagnosing individuals they have never directly examined (sometimes called “diagnosing at a distance”). Claims about parental alienation syndrome or similar constructs that lack recognition in mainstream diagnostic systems can be problematic when presented as established science.

Neuroscience Misapplication: The brain is sometimes treated as the ultimate source of truth in evaluating one’s mental state, which can lead to overinterpreting neuroimaging or making causal claims about behavior based on brain scans without sufficient scientific backing or contextual information.

The primary shield against junk science in the United Kingdom and United States legal systems is the "gatekeeping" function of the judge. In the U.S., the Daubert Standard (derived from Daubert v. Merrell Dow Pharmaceuticals, Inc.) provides a framework for judges to admit expert testimony. To be defensible, an assessment must satisfy several criteria: 

1. Whether the theory or technique can be (and has been) tested.
2. Whether it has been subjected to peer review and publication.
3. Its known or potential error rate.
4. The existence and maintenance of standards controlling its operation.
5. Whether it has attracted widespread acceptance within a relevant scientific community.

Failure to align an assessment with these factors renders the psychologist's testimony vulnerable to "Daubert challenges," which can result in the entire assessment being struck from the record.

Beyond legal admissibility, the use of scientifically sound tools is an ethical imperative codified by professional governing bodies. The APA Specialty Guidelines for Forensic Psychology explicitly mandate that forensic practitioners use assessment procedures that are supported by established scientific foundations. This is a professional standard designed to protect the rights of those being evaluated. When a psychologist utilizes a tool with low validity or "junk" properties, they risk violating the principle of Beneficence and Nonmaleficence, as an inaccurate assessment can lead to unwarranted loss of liberty or even life.

Furthermore, the Ethical Principles of Psychologists and Code of Conduct requires that psychologists base their opinions on information and techniques sufficient to substantiate their findings. In a forensic context, this means that "clinical intuition" cannot supersede empirical data. If a practitioner ignores the Standard Error of Measurement (SEM) or fails to report the limitations of a specific test, they are potentially committing an ethical breach. Adhering to these guidelines provides a "defensive shield" for the forensic psychologist, ensuring that if their methods are questioned, they can point to a consensus-based framework of professional conduct that prioritizes scientific integrity over subjective guesswork.

The persistence of junk science is often fueled by psychological biases within the experts themselves. Adversarial allegiance is a phenomenon where an expert's thoughts and behaviors are unconsciously influenced in favor of the party that retained them (prosecution or defense). This bias is particularly likely in "middle of the road" cases where the evidence seems at least reasonably solid.

Furthermore, experts may fall prey to confirmation bias, the tendency to seek out evidence that supports a favored hypothesis while ignoring contradictory data. This can be especially tempting when there is a large quantity of information to review, and it is up to the forensic psychologist to determine how to weight and organize large troves of data. Confirmation bias often leads to positive testing strategies, where an evaluator searches for evidence of a specific condition rather than objectively exploring all possibilities. Negativity bias also plays a role, as experts may naturally focus on the weaknesses or flaws in a piece of evidence rather than its strengths.

Alarmingly, the legal system's safeguards are often insufficient. Psychological tests are challenged in court in only 5% of cases, according to Neal, and when they are, judges fail to screen out junk science two-thirds of the time.

Forensic psychologists have identified a number of best practices to provide valid, defensible forensic psychological assessments. These include:

• Ensuring all chosen assessment tools are based on sound scientific principles and that they are appropriate for the specific case and population at hand.
• Actively mitigating adversarial allegiance and confirmation bias. Fairly considering alternate hypotheses.
• Clearly conveying data, results, and opinions without overstatement, including a discussion of the assumptions and limits of the findings.
• Following professional guidelines, codes of conduct, and rules of evidence.

Best Practices for Mitigating Bias

To ensure an assessment is truly defensible, psychologists must move beyond simple awareness of bias and implement debiasing strategies. These include:

• The "Consider the Opposite" Technique: Actively seeking out data that contradicts the psychologist's primary hypothesis.
• Blind Data Collection: Whenever possible, having certain data points (like test scoring) processed by someone who does not know the specific details or "side" of the case.
• Technical Manual Adherence: Strictly following the standardized administration and scoring procedures outlined in a tool's technical manual to prevent "clinical drift."

Forensic psychologists would also do well to stay abreast of both the potential uses and limitations of technology in forensic assessments. For instance, integrating tablet computers into forensic and correctional assessments can reduce practical errors, but can be challenging for older users. 

The presence of junk science in forensic psychological assessments is a systemic issue that threatens the integrity of the practice. By recognizing the markers of pseudoscience, such as a lack of falsifiability and extravagant claims, forensic psychologists can steer clear of unreliable tools. Avoiding junk science requires a commitment to foundational validity, the rigorous application of best practices, and a willingness to subject one's work to the highest levels of scrutiny. 

Training

• Criminal Forensic Assessment Certificate
• Identifying and Avoiding “Junk Science” in Forensic Psychological Assessments
• MDLPA: “Folk Psychology,” Heuristics, “Ordinary Common Sense,” & Mental Disability Law
• Evaluations for High Stakes Sentencing: Capital and Juvenile Murder Cases
• Evaluation of Mental State at the Time of the Offense (Insanity/Criminal Responsibility)
• Foundations of Violence Risk Assessment and Management
• Advanced Issues in the Assessment of Risk for Violence: Formulation

Blog Posts

• An Introduction to Violence Risk Assessments
• A Lens on Criminal Responsibility Evaluations in Missouri
• Computerized Assessments Could be a Viable Alternative to Traditional Assessment in Forensic Settings
• New Fordham Risk Screening Tool May Be Able to Accurately Identify Patients In Need Of A Full Violence Risk Assessment - CONCEPT Professional Training
• Adversarial Allegiance Appears Evident in Static-99R Score Reporting and Interpretation
• What Are the Roles and Responsibilities of the Forensic Psychologist?
• It’s all relative: Effect of contrast cases on jury members’ decision making
• Therapeutic Jurisprudence and the Role of Feedback in Forensics
• Bias in Forensic Mental Health Evaluation