Evidence that exposure to child pornography leads to this harm being committed
Neil Malamuth (2018) (available as Free PDF) conducted a massive meta-study to
integrate the vast research literatures on non-consenting adult [pornography] and on child pornography (also a form of non-consenting pornography) by using the framework of the Confluence Model of sexual aggression.
I added [pornography] just to highlight (to make it clear) for some commenters, that it is a given that all child porn involves non-consenting sexual content, and the study included pornography which in turn, includes non-consenting sex with adults.
The Confluence Model of Sexual Aggression is a well-established framework for understanding factors that contribute to men's perpetration of sexual aggression against women, highlighting the roles of hostile masculinity, impersonal sex orientation, and exposure to pornography (Huntingdon, et al. 2020).
Neil Malamuth found that pornography use may add to the risk of sexual aggression only for those men already predisposed to aggress sexually due to more primary causes than pornography use.
To answer the correlation/causation query from @Oddthinking in the comments, near the beginning of page 80 (page 8 of the PDF)
Criminals were more likely than noncriminals to perform some sexual
act, such as masturbation, consensual, or criminal sex after viewing
pornography.
Analyses by these investigators of the degree of physiological sexual
arousal, across 32 studies, indicated that generally sexual criminals
were more aroused than non-criminals (r = 0.15, N = 2099). However,
when the studies separated portrayals of consenting and nonconsenting
sex, it was found that sex criminals were more aroused by non-consenting sex in comparison to noncriminals (r = 0.39)
[...]
2.4.4.2. Correlations within noncriminals (see cell 4b of Table 2). Wright
et al. (2015) conducted a meta-analysis examining the associations
between pornography consumption and actual acts of sexual aggression
within non-criminals. Examining 22 studies from 7 different countries
they did find a significant positive association, both for verbal and
physical sexual aggression, in both cross-sectional and the few available
longitudinal studies. In keeping with the other meta analyses, they also
found that non-consenting content in pornography was an exacerbating
factor.
While this passage doesn't state that any non-criminals turned into criminals, it highlights the risk being there, with non-consenting content making the risk higher.
Further on in the same page, Malamuth points out that
[Ybarra and Thompson (2017)] found that even after controlling for other
potential contributing factors, current exposure to non-consenting
pornography as well as prior exposure to parental spousal abuse were
strongly associated with the emergence of most of the types of sexually
violent perpetration. These conclusions were in keeping with those
found by Ybarra, Mitchell, Hamburger, Diener-West, and Leaf (2011)
wherein 1159 adolescents were followed up over several years. Similarly, in another longitudinal study Brown and L'Engle (2009) reported
that male adolescents were more likely to report having engaged in
sexual harassment perpetration if exposed to sexually explicit material
in early adolescence. Finally, in a two-wave study (separated by a year)
of Polish university students, additional data were provided suggesting
a role for pornography use in predicting attitudes and behaviors.
Tomaszewska and Krahé (2018) found that pornography use assessed at
Time 1 predicted sexual aggression perpetration in the subsequent 12-
month period via its association with sexual aggression perpetration
since the age of 15. The researchers also found that pornography use at
Time 1 significantly predicted attitudes supporting sexual coercion,
which had a direct prospective link to perpetration 12 months later.
Overall, these findings support Wright et al.'s (2015) meta-analyses'
conclusions that both cross-sectional and longitudinal data indicate that
pornography consumption predicts sexual aggression among non-
criminals.
Also, on the same page,
In correlational studies (Type 2 Correlational Studies) does exposure to pornography enable additional prediction of sexual aggression, after controlling for
other known risk factors? Although this type of analysis cannot show
support for causality the way Type 1 Causal Studies can, it can nonetheless better support such a possibility by statistically controlling for
other factors. In other words, does pornography use in and of itself
matter, or are observed cross-sectional and longitudinal relations between pornography use and sexual aggression in some sense illusory
and merely the result of “guilt by association” with other variables,
such as family violence or juvenile delinquency? This question was
addressed in one study by Malamuth et al., 2000 that used a random
sample of the entire USA male population of males who are in some
form of post-high school higher education (about 42% of the male
population). The researchers found that after controlling for key risk
factors (e.g., family violence, delinquency, attitudes accepting of vio-
lence, impersonal sex, and Hostile Masculinity), consumption of pornography remained a significant predictor of sexually aggressive behaviors. Moreover, additional analyses showed that only for those men
who were at relatively high risk (a clear minority of the sample) did
pornography consumption make a significant difference in levels of
sexual aggression...
And he continued with more on that when reading on from there.
Correlation with child porn and child sex offending is covered from page 83 (page 11 in the PDF).
He received some criticism against his findings, and in response, he re-examined his findings (Malamuth, et al. 2000).
In response to some recent critiques, we (a) analyze the arguments and data presented in those commentaries, (b) integrate the findings of several meta-analytic summaries of experimental and naturalistic research, and (c) conduct statistical analyses on a large representative sample. All three steps support the existence of reliable associations between frequent pornography use and sexually aggressive behaviors, particularly for violent pornography and/or for men at high risk for sexual aggression. We suggest that the way relatively aggressive men interpret and react to the same pornography may differ from that of nonaggressive men, a perspective that helps integrate the current analyses with studies comparing rapists and nonrapists as well as with cross-cultural research.
This re-examination is also available as a Free PDF
References
Huntington, C., Pearlman, D. N., & Orchowski, L. (2022). The confluence model of sexual aggression: An application with adolescent males. Journal of interpersonal violence, 37(1-2), 623-643. https://doi.org/10.1177/0886260520915550
Malamuth, N. M. (2018). “Adding fuel to the fire”? Does exposure to non-consenting adult or to child pornography increase risk of sexual aggression?. Aggression and violent behavior, 41, 74-89. https://doi.org/10.1016/j.avb.2018.02.013
Malamuth, N. M., Addison, T., & Koss, M. (2000). Pornography and sexual aggression: Are there reliable effects and can we understand them?. Annual review of sex research, 11(1), 26-91. https://doi.org/10.1080/10532528.2000.10559784