Encyclopedia of Psychology and Law

laboratories do not use validated procedures and stimu-

lus sets. Diagnosis is more likely to be reliable and

more valid when assessment procedures are standard-

ized. For example, sexual history variables that are

associated with pedophilia can be combined to create

a short, easy-to-score scale that organizes diagnostic

decisions on the basis of these variables (Screening

Scale for Pedophilic Interests).

Development

Pedophilia can be described as a sexual preference

that is phenomenologically similar to heterosexual or

homosexual orientation, in that it emerges prior to or

during puberty; is stable over time; and directs the

person’s sexuality in terms of his thoughts, fantasies,

urges, arousal, and behavior. Retrospective studies indi-

cate that some adult sex offenders admit to pedophilia

when they were adolescents, and the average age of

onset of paraphilic behavior among adolescent sex

offenders is around 11 or 12 years. Some pedophiles

have reported being aware of their sexual interest in

children from a very early age, just as other individu-

als report being aware of their opposite-sex or same-

sex attractions early in life.

Risk Assessment

All other things being equal, pedophilic sex offenders

are more likely to sexually re-offend than nonpe-

dophilic sex offenders. There is an interaction between

pedophilia and antisocial tendencies; offenders who

score higher on measures of both factors are much

more likely to sexually re-offend than others. Reflecting

the importance of pedophilia in the prediction of sex

offender recidivism, many of the actuarial risk scales

developed for adult sex offenders include variables that

pertain to pedophilia (e.g., phallometrically assessed

sexual arousal by children, having boy victims).

Examples of these scales include the Sex Offender Risk

Appraisal Guide, STATIC–99, and Rapid Risk Assess-

ment for Sexual Offense Recidivism.

A recent study found that child pornography offend-

ers with no known history of sexual contacts with

children are significantly more likely than men who

have sexually offended against children to be identified

as pedophilic on the basis of their phallometric

responses. This suggests that pedophilia may not be a

sufficient factor to explain the onsetof sexual offending

against children. Antisocial tendencies are also expected

to play an important role, but research on the onset (vs.

maintenance) of sexual offending is only just beginning.

Etiology

There is accumulating evidence that pedophilia is a

neurodevelopmental disorder. Recent studies have

shown that pedophilic men score lower on measures

of intelligence and other cognitive abilities than nonpe-

dophilic men. In addition, pedophilic men are signifi-

cantly more likely to have incurred head injuries

before age 13 and differ by having less white-matter

volume in two tracts that are thought to connect areas

of the brain involved in the identification of visual

stimuli as sexually relevant.

Other research has confirmed the common belief

that many sex offenders against children have them-

selves been victims of sexual abuse as children. Meta-

analytic reviews have found that adolescent sex

offenders have almost five times the odds of having

been sexually abused than other adolescent offenders,

while adult sex offenders have almost three times the

odds of having such a history. These significant differ-

ences are obtained whether the analysis is restricted to

studies based on self-report or studies based on other

sources of information. Moreover, sex offenders with

child victims are more likely to have been sexually

abused than offenders with peer or adult victims; adult

sex offenders who report having been sexually abused

are more likely to admit being sexually aroused by

children; and adolescent sex offenders who were sex-

ually abused showed relatively greater sexual arousal

by children, when assessed phallometrically, than

those who were not abused.

The mechanisms underlying this association between

childhood sexual abuse and sexual offending against

children are not known. Possibilities include imitation

of the perpetrator’s behavior, disruption of emotional

and sexual development, and familial transmission of

predisposition(s) for sexual offending (because many

incidents of child sexual abuse are committed by rela-

tives). The large majority of sexually abused children

do not go on to offend, so there must be individual dif-

ferences in vulnerability. The most obvious candidate

for a vulnerability factor is being male, because most

sex offenders against children are male, yet the major-

ity of child victims of sexual abuse are female. Other

writers have suggested that other vulnerabilities include

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