In Part I on this topic, I focused on the definition of cognitive bias, heuristics, and the risks to custody evaluators and other family law professionals in our work.  In this section, I will focus on strategies for reducing the risks of such bias influencing our work.

Strategies for Detecting that the Evaluator was Not Impacted by These Biases

When I review the child custody evaluation to look  for strengths and weaknesses of the evaluation process, report, and conclusions, among the things I look for is evidence that the evaluator took steps to avoid the risks of such biases from influencing his or her process and thinking.  These strategies will also help the family law professionals understand ways to reduce  their risks of being influenced.  These can include the following:

Evidence of Multi-­Method, Semi-­Formal, Structured Process

One way to reduce the effects of cognitive and professional biases is to engage in a thorough process.  This process includes multiple interviews with each parent, multiple interviews and observations with children and parents in an age-­appropriate manner, possibly psychological testing (to generate hypotheses/areas for inquiry), and multiple and appropriate collateral contacts with people who have a range  of understanding of the family and family issues 1.

Evidence of Sufficient Depth in Questions Being Asked

One of the bigger problems that I see in my review work is the lack of depth in questions being asked by evaluators.  Many evaluators ask the relevant questions to start with, but do so in a relatively superficial manner.  They might ask about each area noted above, but in reading the report, it appears that the evaluator does not understand the issues in any substantial depth.  For example, in asking questions about relocation, many evaluators focus on one set of questions.  The evaluator might ask the parent requesting to move about reasons for wanting to move, but do not ask the parent opposing the relocation why he or she is opposing the relocation.  Similarly, I have seen evaluators ask the parent hoping to move what he/she might do if the court denies the request to move (a practice prohibited in California) but do not ask the parent opposing the move what he  or she might do if the court allows the children to move with the other parent.

Evidence That the Evaluator was Sufficiently Curious

All too often, when reviewing a child custody evaluation, I see a shocking lack of curiosity by the evaluator.  Some evaluators believe that their job is complete once they ask the critical questions.  However, it is very important to get details about the information parents and children (and even collateral witnesses) tell us.  It does not take much time or thought to ask simple follow up questions, such as “Tell me more about that”, “Can you explain what you mean”, or “I don’t understand, I need to know more about that.”  Lacking such curiosity, and failing to follow up with such simple and critical questions, leaves the family law professional vulnerable to oversimplifying complex issues.

Evidence That the Evaluator Managed Common Risks Associated With Known Illusions 1

Using critical psychological research, Chabris and Simons identified six common illusions that influence all humans when engaging in complex tasks.  These include the illusions of attention, memory, confidence, knowledge, cause and potential.  The evaluator’s file needs to have complete interview and observation notes, taken at the time of the interview/observation.  This research clearly demonstrates that evaluators are at risk of missing critical information or failing to remember critical information if their notes are not complete.  For example, a child custody evaluator may have confidence in his or her ability to remember things that occurred in the home visit, but without a record of what occurred, taken contemporaneously with the home visit – not hours or days later – there may be an illusion of confidence and illusion of memory.  The best antidote to these illusions is found in thorough and contemporaneous note-­taking.  Although it’s very rare for evaluators to have video or audio recordings of their sessions, this may be the best way to reduce such risks.

Evidence That the Evaluator Provided Each Parent the Opportunity to Respond to the Allegations Made by the Other Parent

Along with sufficient depth of understanding,  it is important to ensure that the evaluator provided each parent sufficient time to respond to the other parent’s allegations.  Again, if the evaluator simply believes what Parent A tells him, and doesn’t give Parent B sufficient time to respond to the allegations, then there is a significant risk of confirmatory bias or primacy bias, in that the evaluator will not look for data to disconfirm evidence presented by Parent A.  We have also seen such evaluators then ignore data that comes in later in the process when formulating conclusions.

Evidence That the Evaluator Utilized the Proper Evaluative Mindset and Searched for Data that Might Disconfirm a Hypothesis, Not Just Confirm It

Let’s look, again, at the appropriate and necessary evaluator mindset.  Evaluators need to have a mindset in which they don’t believe anything they hear until they check it out.  When I meet with parents for the first appointment, I routinely explain to parents the evaluation process and the evaluator’s mindset (this is part of the process known as informed consent or informed assent).  I explain that I do not believe or disbelieve what I am told until I have a chance to thoroughly evaluate and investigate and until each side has the opportunity to be heard.  When appropriate, I will also check with relevant collateral sources who might be able to provide some information about the allegations.  In my mind, this helps reduce the risk of forming any biases.

Evidence That the Evaluator Considered Data That Supports the Conclusions As Well As Data That Does Not Support the Conclusions

From my perspective, one of the best parts of California Rule of Court 5.220 is the admonition that states, “In any presentation of data, the evaluator must (emphasis added)…present all relevant information, including information that does not support the conclusions reached”1.  This is one of the best ways to demonstrate that the evaluator was not subject to confirmatory bias in thinking through and formulating the conclusions.

Evidence That the Evaluator Considered Multiple Hypotheses and Explained Why He or She Considered Certain Hypotheses More (or Less) Plausible Than Other Hypotheses

One of the most fundamental ways to reduce the risk of being influenced by these various biases is to consider multiple hypotheses in any given case.  Consider a case with allegations of domestic violence and parental alienation (not an uncommon scenario).  In such a case, various hypotheses might include:

• Mother is alienating the children against Father;

• Father has been a perpetrator of Coercive Controlling Violence;

• Though rare and with a lower base rate, Mother has been a perpetrator of Coercive Controlling Violence;

• Both parents have engaged in a pattern of either Situational Couples Violence or Separation Instigated Violence;

• Father has engaged in behavior that, while not abusive, and while Mother may or may not be engaging in alienating behaviors, is also contributing to the child’s alienated responses;

• The child is not being alienated but rather is realistically estranged from Father due to Father’s history of abuse in the family and insensitivity to the child, the child’s personality
dynamics, and the child’s needs;

• Neither parent is overtly contributing to the child’s alienation, but the child is exposed to conflict that is so overwhelming that the child feels a strong need to be pulled in one direction or the other;

• The preferred parent is not actually engaging in overt alienating behavior but instead is psychologically enmeshed or dependent on the child and the child’s alienating responses are more likely related to taking care of the preferred parent (i.e., a parentified response);

• Some combination of these contributions.

As can be seen, in many child custody evaluations, the issues are quite complex and reflect many possible dynamics.  If the evaluator only focuses on the alienation dynamics or only focuses on the domestic violence dynamics in gathering and discussing the data, or doesn’t gather enough depth to answer the hypotheses in the case, the evaluator is at risk of many potential biases, not the least of which include confirmatory bias, pathology bias, and truth lies somewhere in the middle bias.

Evidence That the Evaluator Considered Risks and Benefits of Various Custodial Options

It is not uncommon for an evaluator to consider the allegations and, after reaching a conclusion that some allegation is more likely true than not, reaches conclusions and recommendations based solely on that data.  For example, in the complex case identified above with allegations of domestic violence and alienation, the evaluator who sees evidence of some type of domestic violence may oversimplify the process and determine that significant parenting time should be with the Mother who was seen as the victim of that violence.  The evaluator may also opine that the Mother should have legal custody and decision-making authority so that Father cannot undermine her parenting and continue to engage her in coercive and controlling behaviors.  While this may be the correct recommendation (and in this scenario is likely to be), especially if the court has made a finding of domestic violence, it is still necessary for the evaluator to consider the risks and benefits of other custodial options, i.e., primary time with Father, relatively equal shared time with both parents, and other forms of decision-­making, either joint or with the help of a Parenting Coordinator.  Without such an analysis and consideration of other custodial options, it is unclear if the evaluator has considered all of the data and it is unclear if the evaluator is at risk of being influenced by heuristics, by one of the illusions noted above, or by this emotionally charged family.  A very well-­written report also discusses why certain parenting plan options are not being recommended and shows evidence that the evaluator is not being influenced inappropriately.

If the Statutory or Case Law Requires an Understanding of Certain Factors, Evidence That the Evaluator Considered ALL of those Factors

In my experience, one venue that is primed for the introduction of bias exists in the complex area of relocation.  As noted above, two common biases seen in relocation cases, are “for the move” bias or “against the move” bias.  In Avoiding Bias in Relocation Cases, Stahl 1 identified ways to reduce the risk of bias in relocation matters.  One of the best identified way was to make certain to provide data on all relocation factors identified in either  statutory or case law 1.  I believe that evaluators can evidence their lack of being influenced by one of those biases by addressing each of the relevant statutory or case law factors applicable in their state, as well as any relocation-­specific psychological factors that are identified in the relocation‐related  psychological literature 1.  This is a systematic approach and one, when engaged, that helps the evaluator assess and “think through” each of the factors independently and then as a group.


The purpose of these articles is to raise awareness that all family law professionals, because we are human, are at risk of oversimplifying complex tasks.  In family law, little is more complex than the issues associated with child custody litigation.  Awareness that all family law professionals, because we are human, are at risk of everyday illusions of attention, memory, and confidence.  Awareness that all family law professionals, because we are human, can reduce the risks of being influenced by thorough procedures, including thorough note-­taking, by remaining forever curious, and by considering multiple hypotheses and custodial options before reaching our conclusions.  Most custody evaluators strive to do their highest quality work when advising and guiding families and courts.  Following these practices increases the likelihood of bringing our “A” game to the evaluation of each family we evaluate.


1  Second of two parts

2  Dr. Stahl is a Board Certified Forensic Psychologist, licensed in California, Arizona, Hawaii, and Michigan.  He is a former Board member of AFCC, as well as the CA and AZ chapters and is a regular speaker at AFCC meetings across the country.  When not speaking and writing, Dr. Stahl serves as a consultant and expert witness, as well as a court-appointed child custody evaluator throughout North America.

3  See e.g., Kirkland, K., McMillan, E.,  V, & Kirkland, K. (2004).  Use of collateral contacts in child custody evaluation.  Journal of Child Custody, 2(4), 95-109.

4  See e.g., Chabris, C. and Simons, D., The Invisible Gorilla and Other Ways Our Intuitions Deceive Us, New York:Crown Books,

5  California Rule of Court 5.220, (e), (3), (A)

6  Stahl, Supra note 6

7  See  e.g., Marriage of LaMusga, Marriage of Baures, AZ Rev. Statute § 25-­408, and FL 61.13  for relevant legal factors in relocation cases

8  These psychological factors might include Social Capital or Gatekeeping.  For more information, see e.g., Stahl, PM, Emerging Issues in Relocation Cases, J. Amer Assn of Matrimonial Law, 2013, or Austin, W., [FCR, 2008]