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Bias: Critical Elements to Consider in Forensic Consulting and Expert Testifying

Issues - Spring Edition 2023

Bias: Critical Elements to Consider in Forensic Consulting and Expert Testifying

Philip M. Stahl, PhD, ABPP (Forensic)

Cognitive bias is held to be the greatest risk to forensic neutrality and objectivity in child custody and other forensic work. Many parents often feel that the report writer is biased when a report comes in against that parent’s wishes. It is common for litigants and their solicitors to believe that the report writer did not like the client, did not utilise a neutral process or reached conclusions that are not supported by the data. Because the outcome is unfavourable, and because the process may have been suspect, the belief is that the report writer must have reached this unfavourable conclusion because of bias. Report writers also reach conclusions that are displeasing to a litigant based upon a solid and well-integrated piece of work. Understanding what bias is and is not, understanding various types of bias and understanding how bias can be detected in family law assessments is fundamentally important.

Court rules and professional practice guidelines admonish report writers to avoid the impact of biases in family law work. Court-appointed Single Experts are not advocates for one party, nor are they advocates for a particular outcome. They are advocates for a thorough and scientifically supported process that gathers comprehensive data of a diverse nature, tests various hypotheses, and reaches conclusions that are supported by the data gathered. To accomplish this task, report writers must avoid letting biases of different kinds enter their reasoning.

Heuristics are defined as simple, efficient rules that describe how people make decisions or reach conclusions when faced with complex problems. Family law disputes are usually very complex and the factors that must be considered and weighed when making decisions about parenting arrangements are highly complex. People tend to use a variety of heuristics to solve complex problems, often creating shortcuts in logic and reasoning that may be overly simple due to the challenges of more complex heuristics. Some of these shortcuts lead us to solve complex problems by focusing on simple issues, or only part of the problem, whilst others lead us to ignore some of the information available in order to reach our solutions.

People tend not to see what we aren’t looking for. For example, in areas where pedestrians are more common, there are fewer accidents because drivers are looking out for pedestrians; whereas, in areas where pedestrians are less common there are actually more accidents involving pedestrians because drivers aren’t expecting to see them.

In the same way, report writers who focus on only one element of family dynamics (for example, family violence) might not look at the dynamics associated with other issues (for example, the quality and history of the parenting).

There are many examples of how heuristics and cognitive biases, or blind spots, might operate when assessing a family law matter. Common biases can include the following:

Anchoring Heuristic

With anchoring, the report writer tends to overly rely on certain information during the assessment process at the expense of other information. Once the anchor is ‘set’, there is a risk that other information will be interpreted in a way that is consistent with the anchored information. The ‘Primacy Effect’ is an example of a bias that includes the anchoring heuristic. This is observed in situations where the data we gather first affects the way we interpret and gather later data. The early data thus anchors our understanding of subsequent data and oftentimes limits necessary data gathering.

Availability Heuristic

The Availability heuristic refers to the tendency to focus on what is most available in memory. Things that may increase this availability include data that is more vivid or unusual, or perhaps more emotionally charged. When something is repeated frequently, we tend to remember it more and even believe it more.

Confirmatory Bias

Confirmatory bias is the tendency for a report writer, having formed an opinion or a strong impression before obtaining all the data to start looking for evidence that supports the opinion or impression that has been formed. All subsequent data collected will then be viewed through the lens of the report writer’s early beliefs, to be used to support the pre-conceived opinion as opposed to being fully and neutrally assessed. Data should be gathered in a systematic manner. When data is selectively gathered, there is a greater risk of being influenced by confirmatory bias. Confirmation bias leads to increased confidence in one’s findings, largely because the process of gathering data and data analysis was neither scientifically grounded nor undertaken in a forensically neutral manner.

Recency Bias

Recency bias is the cognitive bias that exists by focusing on the most recent information one has heard and reaching conclusions based on that data. This is the opposite of primacy bias in that there is a tendency to de-emphasise data gathered earlier in the assessment process and to emphasise the data obtained towards the end of the process.


With stereotyping, the report writer is affected by the characteristics of the individual being assessed rather than by the data being collected. For example, if one parent appears histrionic and over-reactive, the report writer might assume that their claims and allegations are as a result of histrionics and give little weight to information that appears to support the allegations being made by that parent. This is particularly troublesome when dealing with allegations of family violence and refuse-resist dynamics and is often consistent with confirmatory bias as well.

Research Bias

There is a risk that the report writer will use research to support a pre-conceived notion (as in ‘research suggests’) without providing citations or describing research that might support a different outcome. This occurs regularly in relocation matters.

The ‘Truth Lies Somewhere in the Middle Bias’

This is often found when report writers are at risk of burnout, having worked in family law for some time. There is a tendency to believe that parents in dispute over parenting arrangements make an equal contribution to that conflict. While that may be the case in some high conflict matters, there are also other instances where one parent drives most of the conflict and the other parent tends to be more reactive to that conflict. This bias prevents report writers from recognising the unique contributions of each parent to the conflict. However, this is an important and relevant factor to consider when determining the specifics of a parenting arrangement. Assigning equal blame to both parents is a mistake when the responsibility for different components of the conflict are more likely caused by one parent than the other.

Relocation Bias

Some report writers see relocation as something to be avoided at all costs, while others tend to take the position that a parent who wishes to move should generally be allowed to do so as long as they have a valid reason for doing so and is not attempting to interfere with the other parent’s time with the child. Some report writers take the approach of determining who the child’s ‘psychological parent’ or primary attachment figure is and may also conclude that this parent may move with the child if there is a legitimate reason for doing so. There is, however, no evidence in the psychological literature to suggest that it is helpful or appropriate for psychologists to have such a presumptive belief in relocation cases and no research to suggest that because a parent is happy following a relocation that a child will adjust to the move. Conversely, there are report writers who perceive that it is a parent’s responsibility to stay near the other parent simply in order to preserve the child’s access to the other parent and the involvement of both parents in the child’s life. While there is research data to support the belief that children derive a benefit from having both parents actively involved in their lives, extrapolating that data to support a presumption against relocation confounds the issue. It is incumbent on report writers not to confuse the preference and value for co-parenting that exists in some research with a presumption that relocation will automatically harm children.


Part 2 will focus on how to review a report and consider whether the report writer might have been blind to critical issues or affected by one or more heuristics, leading to missing data or an over-simplified analysis of the issues. Then part 3 will look at ways to manage and control for bias in our work.


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