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Title: Unresolved issues in scientific sexology
Author(s): Nathaniel McConaghy
Affiliation: School of Psychiatry, University of New South Wales, Australia
Citation: McConaghy, N., “Unresolved issues in scientific sexology,” Archives of Sexual Behavior, vol. 28, no. 4, 1999, pp. 285-318.


This article discusses the state of knowledge in several areas of sexology related to attempts to measure and alter patterns of sexual arousal.

Validity of phallometric assessment

In his attempts to distinguish homosexual men from heterosexual men, Freund found in 1963 that penile volume assessment of sexual arousal in individuals was very accurate, and his findings were soon replicated. Penile circumference measurements have been assumed to be equally accurate, but studies have found that while they can sometimes distinguish between groups, they cannot distinguish between individuals.

For the circumference method to be accurate, subjects must be exposed to more explicit sexual stimuli for longer periods of time. Other studies show that this increased amount of time allows for significantly more faking by subjects. Studies consistently show that circumference methods are inaccurate at measuring deviant sexual arousal.

Thus, due to its unreliability, vulnerability to faking, and lack of standardization, the circumference method of penile measurement should be withdrawn from clinical use until more adequate data are available. However, researchers and clinicians ignore the large amount of evidence, and use it widely to assess and treat deviant arousal. In fact, circumferential phallometry has assumed the leading role in this area.

Lack of evidence that phallometrically assessed sexual preference can be altered

Attempts to change pedophilic and other paraphiliac arousal patterns are based on earlier work attempting to change homosexual arousal to heterosexual arousal. Such attempts accept the conclusion of a 1977 review by Adams & Sturgis that modest changes were found in the direction of reducing homosexual arousal and increasing heterosexual arousal. This review assumed that reported changes in feelings and behavior were equivalent to actual changes in physiological arousal.

The review did not consider the possibility that men in treatment would be motivated to change their behavior, while their physical arousal could remain the same. Even without treatment, homosexual men can do this. In fact, at least half of homosexual men have a history of heterosexual arousal and behavior, showing they are able to function as heterosexuals without treatment. In addition, most men who report homosexual behavior cease such behavior as they age; only a minority of those who report past homosexual behavior actually identify as homosexual.

A 1975 study by the author using penile volume assessment found aversion therapy was no more effective than a placebo therapy in changing homosexuality to heterosexuality. Thus, such change resulted from the motivation to change, not to the therapy.

In addition, studies cited by Adams & Sturgis to support the claim that aversion therapy is effective were severely flawed single case studies. They did not control for expectancy effects and they used inconsistent outcome measures.

In an analysis of behavior changes following aversion therapy, the author found no change in orientation, but there was a lessening of sexual preoccupation and compulsions. He hypothesized a physiological mechanism underlying behavioral compulsions separate from sexual arousal.

Based on this hypothesis, he devised a method to increase the subject’s control of this mechanism, rather than attempting to change his arousal. The method involved training the subject to relax, to visualize situations leading to the compulsive behavior, and to visualize an activity other than that which is compulsive, while still remaining relaxed.

The author conducted controlled randomized studies throughout the 1980s on both covert sensitization and his own method for controlling compulsions. He found that covert sensitization had the same effectiveness as a placebo therapy, but his own method produced a significantly greater reduction in compulsivity than covert sensitization. A one-year follow-up showed that the effect remained. The method had the same effectiveness as low dosage medroxyprogesterone acetate (MPA), and it also reduced non-sexual compulsive behavior.

These studies provide evidence that it is not possible to modify homosexual or deviant sexual preferences, and that treatment should aim at increasing the patient’s control over compulsive aspects of his sexuality. This conclusion has remained unchallenged, but no research has been conducted in order to replicate this finding. Instead, the finding has continued to be ignored or misinterpreted. In fact, in 1992, McAnulty & Adams inaccurately referred to one of the author’s early studies as support for the use of aversion therapy.

McAnulty & Adams reviewed studies supporting the use of aversion and other behavioral therapies for changing deviant sexual arousal without noticing the major flaws in those studies, including their failure to account for the ability of incarcerated offenders to fake changes in their sexual arousal. This is especially important since treatment usually involves repeated and lengthy exposure to stimuli and inaccurate penile circumference measurement. Freund (in 1971) and Wilson (in 1998) showed that subjects increase their ability to fake results when measurement is repeated and exposure to stimuli is lengthy.

The most commonly used method for increasing normal heterosexual arousal in deviants is orgasmic or masturbatory reconditioning, introduced in the 1960s. Evidence supporting its effectiveness is limited to case studies using inaccurate penile circumference assessment. Evidence suggesting that it is ineffective remains ignored.

Marshall & Eccles claim that each time a pedophile has sex with a child, the act conditions their arousal to child stimuli and therefore reinforces arousal to children, entrenching a growing attraction to the act. There is no evidence to support this hypothesis; in fact, a study of heterosexual men failed to show that repeated sex with women produced increasing arousal to them.

Lalumiere & Harris felt that teaching an offender to deceive the therapist by controlling their penile responses might be beneficial since the offender might use this ability to control his arousal in real situations of temptation. However, such a result may be an undesirable outcome which may explain the finding of a California study that offenders who received treatment re-offended more often than those who did not receive treatment.

The failure of changes in penile circumference measures to correlate with behaviors has not led to questioning of the value of procedures aiming at such change. Aversion therapy and prolonged masturbation on instruction seems less acceptable than increasing the patient’s self-control.

Failure to confront evidence of lack of effectiveness of relapse prevention

Meta-analyses of sex offender treatment studies suffer from several flaws. For example, the studies included in the meta-analyses vary in the types of offender groups that are studied, so that comparing effect sizes is meaningless. Statistical evidence shows that offender characteristics rather than treatment methods influence the outcome of treatment. Yet, the effectiveness of treatment is accepted uncritically.

The California study of sex offender treatment mentioned above is the only published randomized large-scale study to compare relapse prevention treatment to no treatment. It involved a mean four-year follow-up component. When the study found that treated offenders re-offended at higher rates than non-offenders, the investigators did not consider the possibility that the treatment method was ineffective. Instead, they performed a post hoc statistical calculation to support the claim that the treatment was effective.

Since 1993, there has been a growing acceptance by psychiatrists that effectiveness of treatments be based on randomized controlled studies. In contrast, in relation to sex offender treatment, there have been increasing recommendations that the methodological rigor of studies be weakened. For example, in 1997, Miner noted that group design studies without randomization do not allow outcomes to be attributed to the treatment, but nevertheless, he wrote that such studies are the design of choice for offender treatment studies.

The belief that when authorities agree, no empirical evidence is needed is demonstrated by the fact that practices with sex offenders that are not supported by empirical evidence are nevertheless recommended by the Association for the Treatment of Sexual Abusers.

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