This piece was reported through The Marshall Project, a nonprofit news organization that covers the U.S. criminal-justice system.

Dr. Gene G. Abel, one of America’s foremost researchers on child molestation, has cultivated an aura of eccentric brilliance. His hair, a tangle of white curls, forks into ample sideburns. He favors loud ties, suspenders, and frumpy little one-liners. “You know,” he said recently, sitting in his Atlanta office, “I’m much more handsome than I appear.”  

At 76, Abel has devoted the majority of his psychiatric career to the minds of those whom many consider the least redeemable. He has interviewed thousands of child molesters and run federally funded research projects on how to identify them. He has taught at Columbia and Emory Universities, authored two books and more than 100 articles in scientific journals on child molestation, and testified before the United States Sentencing Commission on the subject of child pornography. But he is best known for the Abel Assessment for Sexual Interest, a test he has refined over the last two decades. When people are accused of sexually abusing children, this computerized test can help to decide their fates—in decisions about probation and parole, in custody battles, and even in criminal trials.

Mental-health professionals often spend hours interviewing convicted and alleged child molesters and other sex offenders, but they also rely on measurement tools to gather psychological information that a patient might not want to share: Does he have an innate attraction to children? Is it an exclusive attraction or is he also attracted to adults? Does he have other problematic sexual interests that must also be addressed in therapy?

To answer these questions, clinicians have used a variety of tools, including the polygraph, as well as the penile plethysmograph, a device attached directly to the penis that measures arousal. Both of those tests are invasive and hard to administer; taking the Abel Assessment simply involves answering a questionnaire and viewing a series of pictures on a computer screen. With the information it provides in the form of percentages and graphs, clinicians can make more informed decisions about the best course of treatment. Over the last 20 years, Abel estimates his assessment has been administered more than 170,000 times.

One of those times, 10 years ago, the test was given to Rich B. (The two men in this story who were ordered by courts to take the Abel Assessment asked that I withhold their last names to preserve their privacy.) In the midst of a messy divorce, Rich’s daughter told a counselor that Rich had “felt under her shorts.” Such accusations are not uncommon in custody battles, and psychiatrists tend to be cautious about them since children can be swayed to make such accusations by a parent desperate to win full custody. Rich maintained his innocence, passed a polygraph, and was never charged in a criminal court, but the divorce judge ordered him to undergo an evaluation to determine whether he might be a sexual threat to his daughter. As a part of that evaluation, he took the Abel Assessment.

He started with a list of more than a hundred questions. He was asked whether he was attracted to children (he said no) and whether he was interested in non-traditional sexual situations such as sadism, fetishes, or voyeurism (he said no).

Then Rich was told he would look at a series of 160 images, twice. The first time was just for practice. The second time, he had to rate each image on a scale from one (“disgusting”) to seven (“highly sexually arousing”).

It is impossible to know exactly how these instructions were given, but Rich’s description matches that of the journalist Daniel Bergner, who watched a man take the test for a 2005 New York Times Magazine story. Abel’s company said Rich’s description was partially incorrect but that they could not give me any specifics about the test-taking instructions because it might compromise “the integrity of the assessment protocol.”

Rich said he looked at a series of slides depicting men, women, boys, and girls of different ethnicities and ages, all in various situations and states of undress (though never nude). “One picture was a group of people in a crowd,” Rich told me, “and a man with his hand on a lady’s rear end. You know—it’s kind of crude.” In the New York Times Magazine story, Bergner described some of the photos in detail: “A blond woman in somewhat prim white lingerie; then a clean-cut man in a plaid shirt and khakis; then a boy, who looked to me around 12, straddling a bicycle with a book bag over his shoulder; then a girl around the same age wearing a straw hat and eating strawberries; then a pudgy little girl of maybe 4 in a blue one-piece swimsuit.”

Rich spent about two hours completing the test. The clinician sent his results to Abel’s company in Atlanta. Soon after, they faxed back his scores. Rich didn’t see the paper, but it displayed percentages and graphs the clinician had been trained to interpret. Rich was found to have a slight “sexual interest” in children. When the clinician testified to this in family court, Rich’s lawyer challenged whether the Abel Assessment was a credible way to determine the risk Rich posed to his own daughter.

In the end, Rich’s custody level did not change—he continued having supervised visits with his daughter—but he was suspicious of the test and worried that other divorced fathers might find their own claims to custody imperiled if they scored poorly. He found the prospect of having a decision made about him based not on his actions but on his thoughts to be eerie. He searched on Google for more information and published a page about the test on InnocentDads.org, a website he had created for men in his situation.

From Abel’s writings in scientific journals, Rich learned that the test is based on a theory called “visual reaction time.” There are other psychological tests that measure how fast a subject responds to stimuli, including studies of “implicit associations” related to gender and race, but Abel developed his own system independently. He has never published exactly what his assessment measures—and he claims the methodology is more “complex” than the descriptions his company has provided publicly—but at its most basic level, it records how long the subject looks at each image. The test, Abel has written, “assumes that the longer a subject focuses on a slide…the greater the sexual interest in the slide's content.” The implication is that if you linger on images of children, you are more likely to register as having a “sexual interest” in them.

Along with disgruntled fathers like Rich, a handful of professors and practicing psychologists have been grumbling privately and publicly for years about the Abel Assessment. They’ve observed that almost every scientific article about the usefulness of the questionnaire and the test of “visual reaction time” has been written by Abel or others who work directly with him. “Although the scale is widely used in clinical and court cases, there is surprisingly little actual published research with this instrument,” the University of Wisconsin psychology professor Robert Enright wrote in 2012, voicing a concern expressed to me by a half-dozen other mental-health professionals. “There just are not enough studies to give me confidence that the scale has strong and enduring psychometric properties for use in predicting a particular person’s sexual interest.”

Gene Abel in his office (Jason Travis for The Marshall Project)

Such skepticism has not stopped Abel from expanding his business (he charges $2,500 for the software and license and then $99 to score each individual test, though there are discounts). He has developed versions of the test for use with men, women, adolescents, teens, and people with intellectual disabilities. I reviewed more than 40 court decisions over the last two decades and found a large range of uses for the assessment; it is especially popular in quarters of the criminal-justice system where standards of scientific rigor are lower than they would be in a full-fledged criminal trial, from pre-trial, probation, and parole hearings to civil-commitment programs for sex offenders and divorce courts.

People accused of sex offenses have taken the assessment and used favorable scores to obtain therapy instead of a criminal conviction. Convicted sex offenders have found the conditions of their probation or parole—for example, how often they must check in with a probation officer—affected by whether the test found them to have a “sexual interest” in children. Judges have calculated the lengths of sentences partly on the test, and prosecutors have used it to guide the terms of plea deals. It is listed as a tool for court-ordered sex-offender treatment in the official standards of California, Illinois, Texas, and other states. More taxpayer-funded uses—from probation departments (Missouri) to juvenile facilities (Arizona) to adult corrections departments (Minnesota, Montana, New Hampshire, New Mexico, South Dakota, Virginia, Wisconsin)—are listed at Abel’s website.

Some psychologists argue that since the test has not been rigorously validated, it should not be used at all. Others, including Abel himself, say the test should be used as part of larger, more comprehensive evaluations of people convicted of sex offenses (and in some cases merely accused of them). The stakes are high; a poorly designed test, coupled with overzealous clinicians and trusting judges, would be a recipe for railroading innocent people into being judged as high-risk pedophiles (this certainly worries Rich). At the same time, if the test can be easily beaten by actual pedophiles, who study how to control the length of time they linger on each image, then it could put children at risk.

Another issue is that not everyone who has a sexual attraction to children acts on it. There are online support groups for people who pride themselves on restraining their sexual attraction to children. (One is called Virtuous Pedophiles, and has a manifesto which reads, “We do not choose to be attracted to children, and we cannot make that attraction go away.”) Some researchers believe these groups can actually help prevent sex crimes; the University of Toronto psychiatrist James Cantor has called such groups a “potential pressure valve.” Abel himself has found that it is quite normal for adult heterosexual men to be attracted to adolescents. In light of these discoveries, the idea of making decisions about people based on their thoughts, rather than actions proven in an adversarial court system, gives many psychologists and lawyers pause.

As judges in the nation’s courts of appeals have been asked to vet the assessment’s credibility, they have come to widely varied conclusions. Since 2000, they have condoned usage of the Abel Assessment in at least 30 instances and have challenged its credibility roughly a third as often. Though infrequent, some of these challenges have been scathing. In 2002, Texas appellate judge Brian Quinn overthrew a jury’s decision to terminate the parental rights of a father after hearing that he had scored on the Abel Assessment as having a “deviant sexual interest” that would make him a risk to his children. Quinn wrote that since Abel’s scoring methods are not public, they “could be mathematically based, founded upon indisputable empirical research, or simply the magic of young Harry Potter's mixing potions at the Hogwarts School of Witchcraft and Wizardry.”

The cultural image of the pedophile who lurks near local parks and schools, looking for victims, dates back to at least 1950, after a national news story inspired the actor John Wayne to fund a short educational film called “The Dangerous Stranger.” (The film’s director, Sid Davis, later faced criticism for a film called “Boys Beware,” which used the term “homosexual” as a synonym for “child molester”.) The stereotype of the dangerous stranger persisted through the 1980s and 1990s, when a series of high-profile kidnappings, rapes, and murders of children led state legislatures to create sex-offender registries, even keeping some offenders in specialized, locked-down group homes after their sentences had been completed. Still, the psychological conditions that would cause someone to commit and repeat these crimes remained understudied.

Between a panicky public and a lack of good scientific data, Abel quickly rose to the top of the field. From 1994 through 2001, he oversaw a team that conducted one of the largest studies of sex offenders to date. Using Abel’s questionnaire, clinicians in 41 states interviewed almost 4,000 men who had admitted to molesting children under the age of 14. Nearly 70 percent said they had molested a child in their family and only 10 percent described their victims as strangers. In The Stop Child Molestation Book, published in 2001, Abel suggested, “The emphasis on knowing if convicted child molesters live in the neighborhood”—the reasoning behind public sex offender registries—“probably provides less protection for children than was once believed.”

Many of the individuals in Abel’s study said they’d fantasized sexually about children from an early age, and Abel found that while not all child molesters had a diagnosable disorder, teenagers and adults who met the diagnostic criteria for pedophilia (“recurrent, intense sexually arousing fantasies, sexual urges, or behaviors involving sexual activity with a prepubescent child or children”) committed 95 percent of child sex crimes. He described child molestation as a “public-health problem.”

Around the same time he began his sex offender study, Abel started researching “visual reaction time” as an alternative to the penile plethysmograph, a test that was then becoming increasingly controversial. In 1993, New York television reporters found that the plethysmograph (they called it “the device with the funny sounding name”) was being used on teenagers who had inappropriately touched a sibling, in tandem with dubious therapies that aimed to change their thoughts, not just their behavior—for instance, smelling ammonia while looking at deviant sexual images in order to give their brains negative associations. The punk rock singer Jello Biafra commemorated this dark underground of sex offender treatment in the 2004 song “Plethysmograph,” singing, “With our little electronic ring/Clamped around your little thang/Flash ya pictures, Clockwork Orange-style.”

Though it is still employed for some sex offenders—it was recently included in the probation guidelines for former NFL star Darren Sharper after his plea deal for multiple violent rapes—the plethysmograph test has declined in popularity because it is so invasive and can require that the patient look at actual child pornography in order to study arousal, which creates myriad ethical and legal issues.

Abel’s less-invasive approach was based in part on a 1942 study in which the psychologist Saul Rosenzweig asked patients to look at cards depicting sexual situations and measured how long they spent on each. Abel initially used carousel slide projectors, and though the test is now computerized, it still has 160 images, mimicking two carousels with 80 slides each.

Over the past two decades, the Abel Assessment has become a leading tool within a larger field called risk assessment. Since the 1970s, corrections officials and doctors have been relying on questionnaires and other psychological evaluations to help them determine—often based on actuarial data—how likely someone is to reoffend. The initial goal was to allocate resources more efficiently, focusing both treatment and security on those who needed it most. But parole and probation departments also began using these tools to help them determine whether an offender could be safely released back into the community.

The Abel Assessment has also slid backwards through the system into courtroom trials. In 2005, an elementary school teacher in Louisiana named Timothy Brannon was accused of molesting multiple female students. At his trial, a psychologist named Maureen Brennan cited his Abel Assessment score, testifying, according to court documents, that “there was an 81 percent chance that he acted out sexually with children and that he should be expected to falsely deny that fact.” On appeal, Brannon argued that such a claim was “scientifically invalid,” but the Court of Appeal upheld the conviction.

A machine used for plethysmography and other medical tests at Swedish Hospital Ballard Campus in Seattle, Washington (Joe Mabel / Wikimedia)

Since there is such a wide range of cases, there are differing opinions among clinicians, researchers, and courts about how best to use the test, how much weight to give the results, and what constitutes a misuse of the Abel Assessment. “No test or test score can determine the guilt or the innocence of your client for the behaviors of which he is accused,” states a 2005 pamphlet advertising the Abel Assessment to clinicians. Yet the pamphlet also says that test-takers who deny accusations of having molested a child should have their scores measured against the scores of “child sexual abusers who attempt to conceal,” suggesting that the percentage can be used to determine the likelihood that someone is lying. Bret White, the CEO of Abel Screening Inc., told me that the test can determine how likely someone is to have lied about having ever molested a child, but cannot target specific accusations. This, he said, would be a misuse.

Abel argues that it is not his responsibility to regulate how the test is used; it should be up to courts and mental-health professional licensing boards that oversee clinicians in each state. “If they use it inappropriately, you know, I don’t go to their state and say, ‘What are you doing?’” Abel said. “That’s up to the criminal-justice system and the lawyers on both sides.”

He compared the assessment to an EKG. If you have chest pain, he said, and you go to the doctor, the EKG would just be one test you’d be given. You would not rely on it exclusively to make a diagnosis; only a doctor could do that, using the results as one of many considerations. Likewise, an educated and licensed clinician should look at the Abel Assessment results as part of a holistic evaluation that includes other tests, along with knowledge of the patient’s sexual history and perhaps interviews with the patient’s family. Abel does not dictate how to interpret the results, though he does offer advice, should clinicians request it.

Part of the reason the assessment cannot be relied on too heavily, Abel said, is that there is no way to avoid false negatives and false positives (a common issue with most psychological tests, given the complexity of the human brain). Nine percent of men who have not sexually abused a child show up—falsely—as having done so, according to Abel.

Such caveats are cold comfort to men who maintain their innocence. Richard—who, like Rich in North Carolina, asked me not to use his last name—was accused of molestation by his 5-year-old stepdaughter in May 2013. According to court documents, she claimed that he came into her room late at night, “touched the area where she goes pee,” and “put things in her anus.”

Though Richard admits that he did things that could be called abusive (he once threw a cup of ice at the girl), he denies these sexual accusations. He has never been charged; the police have stopped investigating, since there is no evidence to support the accusations and the stepdaughter’s statements have been inconsistent. Therapists who have interviewed her have made competing determinations.

The couple also had a son together, now about a year old, and Richard wants partial custody. The divorce began before the boy’s birth, so Richard has never met him.

This past January, the family court judge overseeing Richard’s divorce looked at reams of clinical evaluations and police reports, and remained uncertain as to whether he would pose a sexual threat to his son. Relying on the opinion of Jane Ward, a psychologist in Portland, Oregon, the judge decided that Richard should not have contact with his son until he has undergone a full “psychosexual evaluation” to determine whether he has “pedophilic tendencies.” That evaluation, Ward wrote, should include a plethysmograph or an Abel Assessment, and until then “he should not have any supervised time with any minor children, including his biological child.”

Richard is torn about whether to take the assessment, since the wrong result could lead to a renewed push from police to charge him with a serious crime. His criminal defense lawyer has urged him to stay away, but, Richard said, “My family court attorney said I should take the test to prove my innocence.”

While weighing access to his son against the potential for failure on the Abel Assessment, Richard found the website InnocentDads.org. After reading about the test, he decided not to take it or the plethysmograph, even at the risk of never meeting his son. His case is currently at a standstill.

When I ran Richard’s concerns by Ward, the psychologist who ordered the evaluation, she echoed what she’d written in her original affidavit: Tests like the Abel Assessment should never be used as “a sole measure of deviance” but only in combination with numerous other evaluations, family interviews, and court documents. “Psychological assessments, psychosexual assessments, and risk assessments are not an exact science. They never will be because people’s behavior is not always predictable,” she told me. “I am sure that there are times when I err on both sides—not protecting the child enough and not protecting the alleged perpetrator enough. It’s not easy work.”

When I started learning about the Abel Assessment, I asked Abel and several clinicians whether I could take the test myself. I wanted to describe the experience of clicking through the pictures, and while I consider myself part of the majority of people who have never felt a sexual interest in children, I wanted to see if the test might say something about me I did not feel to be true, as it had for Rich and presumably other men.

Abel would not condone this, and clinicians—following their licensing agreement with him—would not show me the questions in the questionnaire or the pictures used to measure “visual reaction time.” Though Abel freely discussed the history of the test, he was very protective of these specific details, arguing that if too much information gets out to the public, real child molesters can figure out how to beat the test.

Clinicians are divided on whether that’s possible and whether molesters already are beating it. Karen Franklin, a forensic psychologist in California, told me she found an online forum in which predatory and unapologetic sex offenders traded notes on how to fool the test of visual reaction time (though the link she found has since gone dead). “You’ll laugh when you find out just how easily the test can be beaten!” someone wrote, according to Franklin’s blog. “The entire thing rides on the theory that no one will know what it’s really testing.”

“I work with people who lie and people who are trying to conceal what they’ve been involved with,” Abel said. “I’m very aware that others try to figure out how we score things, and I’m very aware that individuals on the Internet report ‘exactly’ how it works.” But, he maintained, those sites are often riddled with errors.

Abel also contends with anonymous, ad hominem attacks online. One of his colleagues, Whitney Gabriel, said she “cringes” when she sees pages like Abel’s Wikipedia entry, which refers to him as a “controversial clinician.” She has tried to get the entry taken down, but a Wikipedia editor refused, noting that the claim seemed “sufficiently sourced.” (It cites a clinical handbook that briefly summarizes some conflicting opinions on the test’s usefulness.)

When I asked Abel if the test secretly measures how long the taker looks at certain images relative to others, he said yes. But then he reversed roles, asking me questions in order to demonstrate just how successfully he has concealed the most crucial information about his assessment, which he believes is key to maintaining its integrity. He asked if I knew whether the test measures visual reaction time during the first or second time the taker clicks through the images.

“My understanding is that it’s the first time,” I said.

“So you don’t know,” he said. “That’s the first thing you don’t know. I’m just using you as an example … There are 160 slides … Which slides do we use to measure?”

“I have no idea,” I responded. “I’ve never seen the test.”

“That’s two. The third thing is how do you tell when the measurement starts and finishes … So an image comes up. When do we start measuring [the reaction time]?”

Of course, I did not know.

Abel is now in the midst of expanding his business with another proprietary testing tool, The Diana Screen, which is marketed to non-clinicians with the purpose of preventing molestation. It has been tested in pilot projects with The Episcopal Church Pension Fund and The Boys and Girls Clubs of America. It is supposed to be able to help organizations determine whether a job applicant might pose a “sexual risk to children.” Abel’s company markets it to churches, summer camps, schools, and foster care agencies, and it is already used by juvenile detention and residential treatment centers.

When applicants take The Diana Screen, there are no pictures—only a lengthy questionnaire—so it is easier to administer than the Abel Assessment. The responses are measured against a data pool, as well as information from professional literature and the FBI. Abel’s company tells clients that they should not deny someone a job solely based on their failure on the screen, and that the result “should be used as one part of the organization's overall decision-making process.”

The warning is not enough for some psychologists, who worry that people will be denied jobs based solely on the results of the screen, even when they may in fact pose no threat. Others worry the test will, as psychologist Anna Salter put it, give organizations a “false sense of security.”

Abel takes the flak in stride, he told me, because his goal is to stop a tragedy he feels society at large does not address with enough frankness. He views his life’s work as an effort to show Americans that they need to be more proactive about preventing child sexual abuse, noting just how wrong the prevalent stereotypes about strangers have tended to be. “Child molesters are your neighbors and people you know,” he said as we sat in his office that afternoon. “They’re hiding in plain sight.” Whatever the flaws of the Abel Assessment, he argued, the result of not having such tools—and failing to prevent the sexual abuse of children—would be far worse. “This is not a perfect test,” he told me. “There are no perfect tests.”