Syndrome Testimony, Base Rates, and What the Expert Can Ethically Tell the Trier of Fact in Alleged Child Abuse Cases

Jack S. Annon, Ph.D.*

In many alleged child abuse cases, the issues of recantation, delay of disclosure, and physical, emotional, and behavioral symptoms of abuse are often described by expert witnesses to the trier of fact.  However, it is my firm opinion that there are three important topics that are relevant in determining what an expert in this area could ethically testify about: a) syndrome testimony, b) base rates, and c) what the expert can and can not tell the trier of fact.

Syndrome Testimony

The issues of "recantation" and "delayed disclosure" have been popularized by Roland Summit (1983) as two of the five predictable stages, or events, that a child who has been sexually abused may allegedly go through.  This is outlined in his proposed Child Sexual Abuse Accommodation Syndrome.  This is only one of many such syndromes that have been offered in courts in recent years (e.g., Parental Alienation Syndrome; Child Sex Abuse Syndrome; Battered Child Syndrome; Battered Wife Syndrome; Rape Trauma Syndrome).

In order to understand the term syndrome, it may help to clarify and define some terms.  A sign is an observable manifestation of a pathological condition seen by the examiner (red splotches associated with measles).  A symptom is generally considered a subjective complaint by the individual (reporting a headache).  A disease or disorder is a group of symptoms or signs that occur together, and implies a specific cause or pathophysiologic process.  On the other hand, a syndrome is a group of signs and symptoms that are based on their frequent mutual occurrence that may suggest a common underlying course, pattern, or treatment selection, but do not necessarily imply a specific cause.  Therefore, to start with, a syndrome is less specific than a disorder or a disease.

Myers (1992) suggests that it is important to locate syndromes on a "continuum of diagnostic certainty."  Some syndromes point with greater certainty to their causes than others do.  For example the Battered Child Syndrome (Kempe, Silverman, Steele, Droegemueller, & Silver, 1962) points convincingly to abuse from a medical viewpoint, and has a very high degree of diagnostic certainty (physicians look for injuries to the child that are inconsistent with the description of how the injuries came about, and they also look for previous unreported injuries.  On the other hand, those syndromes that fall outside the traditional meaning of syndrome and do not point to a particular cause are considered to be "non-diagnostic syndromes" and, according to Meyers, should not be admissible as evidence to prove that a person's symptoms resulted from a particular cause.

The Child Sexual Abuse Accommodation Syndrome is an excellent example of a non-diagnostic syndrome.  This syndrome, or any components of it, does not detect sexual abuse, rather it makes the assumption that sex abuse has already occurred and it explains the possible reactions that an abused child may experience.  Rotgers and Barrett (1996) have pointed out that the syndrome is "speculation" having neither empirical nor theoretical basis in science.

Summit (1992) himself has subsequently stated that the syndrome was not designed to "prove" that abuse occurred, but to explain children's reactions to sexual abuse.  He wrote, "The CSAAS originated, then, not as a laboratory hypothesis or as a designated study of a defined population.  It emerged as a summary of diverse clinical consulting experience, defined at the interface with paradoxical forensic reaction.  It should be understood without apology that the CSAAS is a clinical opinion, not a scientific instrument" (p.156).  By his own admission, there is no empirical research support for the syndrome, or the theory on which it is based, or what percentages of children experience such events.

Summit also stated that, "Syndrome evidence has become a generic term for diagnostic medical or psychological testimony which must be closely scrutinized for scientific reliability, lest the intrinsic authority of the expert witness improperly prejudice a jury through contrived or eccentric opinion."  And shortly after, "Had I known the legal consequences of the word at the time, I might have better chosen a name like the child sexual abuse accommodation pattern, to avoid any pathological or diagnostic implications" (1992, p. 157).

Myers (1992) sums up this area well when he points out that, if a syndrome is non-diagnostic, it goes without saying that it should not be admissible to establish the cause of a patient's symptom.  Why this has caused so much trouble with the courts is that examiners do not explain to the judges or juries the distinction between diagnostic and non-diagnostic syndromes.  In a review of 45 studies (Kendall-Tackett, Williams, & Finkelhor, 1993) found that no one symptom characterized a majority of the sexually abused children.  Most importantly, they found that approximately one-third of the victims had no symptoms whatsoever.

In conclusion, from the above it can be seen that there is no single behavioral symptom, or syndrome, that is characteristic or indicative of child sexual abuse.  To the point, recantation or delayed disclosure by itself does not directly indicate that a child was sexually abused, or that a child was not sexually abused.

[For a more thorough and in depth presentation of this issue see the chapter Special Issue: Legal Issues; the Witness, Syndrome Testimony, and What the Examiner Can Tell the Trier of Fact, from my course textbook (Annon, 1996).]

Base Rates

This is an important concept that many expert witnesses fail to take into consideration when testifying in this area.  Quite often, a witness testifies that, if a given child displays a number of signs, symptoms, or behaviors (such as "sexualized behavior" or "recantation" or "delayed recall", etc.), then the child has most likely experienced sexual abuse.

How many signs or symptoms are necessary before a syndrome can be concluded, and what is the prevalence of the syndrome in abused versus non-abused children?  To understand the difficulty of making conclusions based on such signs or behaviors it is important for the expert to understand the concept of base rates that unfortunately very few professionals understand.

For illustrative purposes, let's assume that there is a particular state in which there are 220,000 children.  Let's hypothetically assume that 20,000 of these children have been shown to be sexually abused.  Let's take another step further and in examining these children, we find that 75% of the abused children display symptoms of nightmares, bed-wetting, depression, and sexualized behavior.

Notice that 75% of the 20,000 children means that 15,000 of the abused children have displayed this combination of signs and symptoms.  At this point, we examine an allegedly abused child and find this combination of signs and symptoms in the child.  Because 75% of our abused group displayed them, we might erroneously believe that there is a 75% probability that this child we have examined was also sexually abused.

However, let's take it one step further; remember we are talking about 20,000 out of the 220,000, which leaves 200,000 children who presumable were not abused.  Assume that we examine these, non-abused children and find that only a small 10% of these children exhibit the symptoms of nightmares, bed-wetting, depression, and sexualized behavior.  At first glance it appears obvious that when 75% of the abused children show such signs, and only 10% of the non-abused children show the signs, then there must be a higher probability that the child we are examining has been sexually abused.

However, notice that 10% of the non-abused population of 200,000 still means that 20,000 children now are in this non-abused group with the same symptoms as the abused group.  If we take the number of children who have experienced the symptoms in the abused situation (which is 15,000), and add them to the number of non-abused children, (which is now 20,000) we now have a pool of 35,000 children with the symptom combination.

What is most important to note here is if we now mix up this pool so that we cannot identify anyone, then randomly pick a child out, of the pool, there is a higher probability that we will select a child from the non-abused population, as compared to the abused population, and yet believe that we have an abused child., even though only 10% of the non-abused population has the symptoms, and 75% of the abused population does.

these figures could be changed in any way.  The point is, while we may have a lot of information from research and clinical practice concerning rates for abused children, it is extremely important to obtain base rates from the general population of non-abused children before we can offer any firm opinion as to the probability of whether a child has or has not been abused.

This should be kept in mind for any examiner who is looking for any signs, symptoms, or syndromes in any given population.  This is why such studies as Friedrich, et al.(1991) that gathered normative sexual behavior on presumably non-abused children are so important.  Equally important are Friedrich et al.'s (1992) subsequent studies where they compared sexual behavior between abused and non-abused children.

It can be seen in these studies that some behaviors that have been put forth, including sexualized behavior, as indicators of sexual abuse are also found in non-abused children.  On the other hand, there are also some behaviors found in abused children that are very rarely found in non-abused children.  It is very important for any expert witness to keep base rates in mind if they are going to make any kind of evaluative statements about what a given sign, symptom, or syndrome indicates.  [For further information on this subject refer to Annon, 1996.]

What the Expert Can and Can Not tell the Trier of Fact

In the past, the Frye (1923) general acceptance standard for expert testimony was not used that much in mental health cases, which relied a lot on the clinical experience of the individual offering testimony.  However, in 1993 with the advent of the Daubert v. Merrill Pharmaceuticals opinion by the United States Supreme Court, this situation began to change.  This opinion again caused quite a stir for forensic and mental health experts.  Some felt it would open the gates to all types of evidence, while others suggested it would lock the gates to a lot of junk science.

The first commentaries on the shift was by Underwager and Wakefield (1993), who pointed out that this finding replaced the Frye test with the principal of "falsification" as a determinant of scientific knowledge.  It was their opinion that if the concept of falsification is properly understood and followed by the judges, it would most likely render inadmissible testimony based on such concepts or theories as the Child Sexual Abuse Accommodation Syndrome, and other similar issues.

One of the characteristics that was pointed out by the Supreme Court was the concept of falsifiability.  In other words, do credible research studies produce results that mean the theory cannot be held, or continue to be maintained.

The other concept of falsifiability is that the theory or concept in question must be capable of being falsified.  Could it be definitively or conclusively falsified?  Wakefield and Underwager noted that much of the expert testimony in cases of alleged sexual abuse is unfalsifiable.  They maintained that this type of testimony should be declared inadmissible, as it is not helpful to the trier of fact.  For example, if the accused proclaims innocence, then the individual is in denial.  If the accused shows little or no emotion when being questioned, then he must be in denial, or sociopathic, or a manipulator.  On the other hand, if the accused becomes emotional or tearful when confronted, then he is overwhelmed by guilt and disgust by his behavior.

Most to the point are statements by so-called experts about the alleged victim that can not be falsified.  For example, the issue of immediate disclosure or delayed disclosure is equally supported.  If the child "discloses" abuse immediately after the alleged abuse occurred, the child is seen as overwhelmed by the abuse, or is too fearful to maintain the secret, or has found him or herself in a "safe" situation within which to disclose the abuse.  On the other hand, if the child "discloses" abuse years after it allegedly happened, it is assumed to be typical of abused children that they will delay disclosure.  As can be seen neither one of these positions can be falsified or disproved.

Also, to the point, it is said that abuse is supported when the child initially acknowledges alleged abuse, but then recants or retracts an earlier statement.  Though recanted or retracted, the abuse allegation is still true because the child is under pressure to recant and is scared.  Recantation is described as "typical" of children who have been abused and, therefore, cannot disprove abuse.  Thus, another opinion that cannot be falsified (see Wakefield and Underwager, 1993 for a more comprehensive discussion of this issue).

The fact is, most children who initially allege abuse do not retract their statements, and there are a smaller number that do retract.  Some who retract their statements have been abused, and some that retract have not been abused.  What is the base rate for these situations, and how do you determine which statement is true?  Retraction by itself does not mean that abuse did occur, or that it did not occur.

Unfortunately, the Daubert gate-keeping function did not keep such opinions out of our courts.  In Hawaii, many "expert witnesses" are allowed to testify to many issues that have no empirical research support and are not capable of being falsified.  The usual reason is that their testimony is not considered "scientific" but is based on "technical" or other "specialized knowledge" (for further information on this subject see, Annon, 1996).

However, in the wake of the recent 1999 Kumho Tire Company. v. Carmichael United States Supreme Court decision, this may finally change.  The court's decision that the Daubert gatekeeping obligation also applies to testimony based on technical and other specialized knowledge, as well as scientific knowledge, may now truly screen out "junk science" and the testimony of many so called "mental health experts" with little awareness of the issues of syndrome testimony, base rates, and falsifiability.

This sums up the database that expert witnesses in this area should be aware of and knowledgeable about before the proffer themselves as expert witness in alleged child abuse cases.


Annon, J. S. The Forensic Detection of Deception, Distortion, and Malingering in the Witness, Victim, Defendant, and Patient, Course One: Forensic Aspects of Memory and Recall in Children. Adolescents. and Adults. A distance course of the American College of Forensic Examiners, (1996).

Daubert v. Merrell Dow Pharmaceuticals, Inc., 113 S.Ct. 2786 (1993)

Kempe, C. H., Silverman, F. N., Steele, B. F., Droegemueller, W., & Silver, H. K. (1962). Battered-child syndrome. Journal of the American Medical Association, 181, 17-24.

Friedrich, W. N., Grambsch, P., Broughton, B., Kuiper, J., & Beilke, R. L. (1991). Normative sexual behavior in children. Pediatrics, 88, 456-465.

Friedrich, W. N., Grambsch, P., Damon, L., Hewitt, S., Koverola, C., Lang, R., Wolfe, V., & Broughton, D. (1992). The child sexual behavior inventory: Normative and clinical comparisons. Psychological Assessment, 4, 303-311.

Frye v. United States, 293 F. 1013 (D.C. Cir. 1923)

Kendall-Tackett, K. A., Williams, L. M., & Finkelhor, D. (1993). Impact of sexual abuse on children: A review in synthesis of recent empirical studies. Psychological Bulletin, 113, 164-180.

Kumho Tire Co. v. Carmichael, 119 S.Ct. 1167 (1999).

Myers, E. B. (1992). Evidence in Child Abuse and Neglect, 2nd edition, v. 1(Hardcover (3rd Ed.)) & 2, New York: John Wiley & Sons.

Summit, R. C. (1983). The child sexual abuse accommodation syndrome. Child Abuse and Neglect, 7, 177-193.

Summit, R. C. (1992). Abuse of the child sexual abuse accommodation syndrome. Journal of Child Sexual Abuse, 1, 153-167.

Underwager, R. & Wakefield, H. (1993). A paradigm shift for expert witnesses. Issues in Child Abuse Accusations, 5(3), 156-167.

* Jack S. Annon is a clinical and forensic psychologist at 680 Ainapo Street, Honolulu, Hawaii, 96825.  [Back]

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