Research: The effects of pornography

Research flaws and false constructs
Methodological flaws/false constructs

Minor-Adult sex
Prevalence of harm Association or causation? Secondary harm Family environment Effects of age on outcomes

Minors
Commercial and online victimization Youth sexuality Sexual repression Cognitive ability Teen pregnancy Effects of pornography

"Child Sex Offenders"
Characteristics of the offender Who offends and how often? Recidivism

Minor attraction
Child pornography Cognitive distortion Abnormal psychology Pedophilia as an orientation Nonsexual aspects Prevalence Dangers of stigma A "cure" for pedophilia?

Broader perspectives
Non-human relationships Historical relationships Nonwestern relationships Double-Taboo (Incest, Prostitution) Evolutionary Perspectives

Template: Research - This template

The harm thought to be caused to minors by pornography and other "inappropriate content" is not supported by any properly controlled outcome studies or other scientific evidence, much like the highly politicized concept of "porn addiction".^[1] "Moral harms" and "(age) appropriate" socialization of youth are instead the rationales given for policing this content. Throughout much of the professional literature, preventing minors from accessing this material is still assumed, a-priori, to be a rightful and realistic goal.

Many of the reports commissioned by governments and NGOs use correlational studies, which do not establish cause and effect,^[2] and are plagued with negative value judgments concerning "high risk behaviors" and "permissive attitudes". This lack of evidence casts doubt upon the use of imprecise and expensive internet filters by central governments, and the insistence of some governments upon self-regulatory ISP models. At the same time, content warnings are in general known to be ineffective or even counterproductive.^[3]

The usually biased Wikipedia, essentially comes to the same conclusions as this article, i.e. that this field of study is characterized by a battle over interpretations of correlational data between moralists, advocacy scientists and rational scientists.

Politics and Pornography: Historical context

In 1969, the United States Supreme Court ruled in Stanley v. Georgia that people could view whatever they wished in the privacy of their own homes. In response, the United States Congress funded the President's Commission on Obscenity and Pornography, set up by President Lyndon B. Johnson to study the topic. The report^[4] was firmly based in science, and recommended that all restrictions on access for adults should be lifted. It also found that there was:

"no evidence to date that exposure to explicit sexual materials plays a significant role in the causation of delinquent or criminal behavior among youths [...]".

In events closely resembling the later Rind et al controversy, the report was widely criticized and rejected by Congress. The Senate rejected the Commission's findings and recommendations by a 60–5 vote, with 34 abstentions. President Nixon, who had succeeded Johnson in 1969, also emphatically rejected the report, and publishers William Hamling and Earl Kemp (who published an illustrated version) were sentenced to prison for "conspiracy to mail obscene material".

Reagan's Meese Commission (1986), said to be laden with conjecture and led by its conclusions, overturned the Commission's findings without any scientific evidence and laid the groundwork for an intensification of the CP witch-hunt. Meese was published in an increasingly censorious environment; as our timeline reveals, Satanic Panic was already well underway. For example. Patrick Califia notes:

Highly touted "new research" that was to show a link between pornography and violent crime simply doesn't exist. The Commission hired Canadian sociologist Edna F. Einsiedel to review and summarize existing studies that might have a bearing on their findings. She reported, "No evidence currently exists that actually links fantasies with specific sexual offenses; the relationship at this point remains an inference." She also noted that pornography has been of value to some therapists who use it to treat patients. For writing this report, Einsiedel was placed under a gag order obtained by Alan Sears, and her summation does not appear in the Commission's Final Report.^[5]

The policy context within the UK is covered by Jim Greer in his 2015 book chapter. Similarly, he concludes that evidence is scant, and the UK is experiencing moral-panic type conditions concerning the exposure of minors to explicit content.^[6]

To this very day, there exists an increasingly powerful and well-funded anti-porn and anti-trafficking lobby in America, with NCOSE being the prime example. This alliance has links to both right-wing/Christian extremism and the anti-sex #MeToo movement.^[7]^[8]^[9]

More recent evidence

Selection of banners found on a website associated with the parents rights movement^[10]

This topic is considered almost impossible to study by present-day authors, at least within an experimental context. As Rory Reid, in Segal's article below notes, "universities don't want their name on the front page of a newspaper for an unethical study exposing minors to porn."

Svedin CG, Donevan M, Bladh M, Priebe G, Fredlund C, Jonsson LS. (2023). Associations between adolescents watching pornography and poor mental health in three Swedish surveys. Eur Child Adolesc Psychiatry. Sep;32(9):1765-1780. doi: 10.1007/s00787-022-01992-x.
"The repeated cross-sectional surveys did not find any consistent associations across years between poor mental health and ever having watched pornography or the frequency of watching pornography. Having watched deviant pornography (containing violence, children and/or animals) was associated with poor mental health among boys in two surveys but only in one survey among girls. Other characteristics, such as mother's unemployment (especially boys), parenting style (especially high controlling parents among boys) and experiences of sexual abuse (especially penetrating abuse among girls), were more consistently and strongly associated to poor mental health across the three surveys. This study stresses the importance of controlling for multiple background variables when studying the association between watching pornography and mental health, since the association might primarily be explained by underlying confounding variables."

Štulhofer, A., Tafro, A. & Kohut, T. (2019). The dynamics of adolescents’ pornography use and psychological well-being: a six-wave latent growth and latent class modeling approach. Eur Child Adolesc Psychiatry 28, 1567–1579, doi: 10.1007/s00787-019-01318-4
"To explore possible links between adolescent pornography use and psychological well-being more systematically, this study focused on parallel dynamics in pornography use, self-esteem and symptoms of depression and anxiety. A sample of 775 female and 514 male Croatian high school students [...] was used for the analyses. [...] We observed no significant correspondence between growth in pornography use and changes in the two indicators of psychological well-being over time in either female or male participants. However, a significant negative association was found between female adolescents’ pornography use and psychological well-being at baseline."

Francis Black (2022) Don’t Worry, the Kids Are Alright
“When age at first exposure is modeled as a statistical variable, it explains a small portion of the variance in self-reported negative effects stemming from pornography. When it came to self-reported negative effects from pornography, Mulya and Hald (2014) found age at first exposure to explain only about 1% of the variance of the self-reported negative effects from pornography. (-0.14^2=1.96%).[...] Similiarly, Miller, Hald, and Kidd (2018) found it to explain about 2% of the variance in self-reported negative effects (-0.12^2 = 1.44%)."

McKee, Alan (2010) Does pornography harm young people? Australian Journal of Communication, 37(1), pp. 17-36.
"Retrospective studies show that accidental exposure to real-life scenes of sexuality does not harm children. Our survey shows that age of first exposure to pornography does not correlate with negative attitudes towards women. Studies with non-explicit representations of sexuality show that young people who seek out sexualised representations tend to be those with a pre-existing interest in sexuality. These studies also suggest that current generations of children are no more sexualised than previous generations, that they are not innocent about sexuality, and that a key negative effect of this knowledge is the requirement for them to feign ignorance in order to satisfy adults’ expectations of them."

"When asked to think about the effects of early exposure to pornography, the interviewees uniformly recalled other elements of their lives as having a more negative effect on their attitudes to sexuality, including: the media, social attitudes towards women, ‘peer pressure about boyfriends’ and religion (McKee, 2007c, p. 119)."

"Our data shows that since the 1950s the trend is for each generation to encounter pornography earlier than the generation before. Our study also showed that every generation of men has better attitudes towards women than the previous generation (McKee, Albury and Lumby, 2007, p. 80)."

"[...]for children, their parents’ expectations caused more problems for them than the information they encountered about sex. Children are quite aware that parents want them to be ignorant about sex; and they consciously perform this ignorance for them. [...] More than this, the need to pretend to be innocent for their parents was one of the most distressing things about their experience with sexuality in the media: ‘for some, much of the embarrassment … seemed to derive from having to pretend that they did not know about such things, in order to keep their parents happy’ (Buckingham and Bragg, 2005, p. 62)."

Luder, MT., Pittet, I., Berchtold, A. et al. (2011). Associations Between Online Pornography and Sexual Behavior Among Adolescents: Myth or Reality?. Arch Sex Behav 40, 1027–1035. doi: 10.1007/s10508-010-9714-0
"This study aimed to compare the sexual behavior of adolescents who were or were not exposed to online pornography, to assess to what extent the willingness of exposure changed these possible associations, [...] We conclude that pornography exposure is not associated with risky sexual behaviors and that the willingness of exposure does not seem to have an impact on risky sexual behaviors among adolescents."

Researchers, Educators and Therapists in Support of Appellee in United States v. Playboy Entertainment Group (published March, 2003). Brief Amici Curiae of Sexuality Scholars. No. 98-1682 (Oct. Term 1998), p. 8.
"Most scholars in the field of sexuality agree that there is no basis to believe sexually explicit words or images … in and of themselves cause psychological harm to the great majority of young people."

UNICEF (2021). Digital Age Assurance Tools and Children’s Rights Online across the Globe. A Discussion Paper.
"There are several different kinds of risks and harms that have been linked to children’s exposure to pornography, but there is no consensus on the degree to which pornography is harmful to children. [...] As discussed above, the evidence is inconsistent, and there is currently no universal agreement on the nature and extent of the harm caused to children by viewing content classified as pornography. However, policymakers in several countries have deemed that children should not be able to access commercial pornography websites designed for users aged over 18."

McCormack, M., & Wignall, L. (2017). Enjoyment, Exploration and Education: Understanding the Consumption of Pornography among Young Men with Non-Exclusive Sexual Orientations. Sociology, 51(5), 975–991.
"This research has drawn on interviews with 35 young men with non-exclusive sexual orientations to examine how their consumption of pornography has influenced their lives and identities. Adopting an inductive analytic approach, our findings support the growing body of research that problematizes what we have called the negative effects paradigm (Ruddock, 2015), where studies explore the potential harms associated with pornography consumption to the exclusion of other possible outcomes. Instead, our participants consumed it as a leisure activity, and found it educational in a number of ways – supporting McKee’s (2012) contention that pornography should be viewed as a form of entertainment rather than as a potential harm. [...] In addition to a source of sexual gratification, pornography was also used to relieve boredom, bond with friends and as a source of pleasure. Importantly, our open-ended questions meant that there were numerous opportunities for social harms related to pornography to be raised – yet the only problems related to parents finding out about pornography consumption. The negative effects of pornography consumption for our participants were not related to the content of the pornography but how their parents reacted to them watching it.

Thornburgh, Dick; Lin, Herbert S., eds. (2002). Youth, pornography and the Internet. Washington, D.C: National Academy Press. p. 155.
"Although some literature exists on traditional forms of media (e.g., television, radio, magazines), the empirical research that examines the impact on children of exposure to non-violent sexual material is extremely limited."

Becker, J., & Stein, R. M. (1991). Is sexual erotica associated with sexual deviance in adolescent males? International Journal of Law and Psychiatry, 14(1-2), 85–95.
"This study did not demonstrate a relationship between sexually explicit material and number of victims. Furthermore, the majority of youngsters surveyed did not feel that using sexually explicit material played a part in the commission of a sexual offense."

Segal, David (4 April 2014). "Does porn harm children?" (Live version also available outside of Europe - September 2022) Dallas News.
"And here is where the topic starts to get very murky. It turns out that the research suggesting that teenagers and pornography are a hazardous mix is far from definitive. In fact, many of the most comprehensive reports on this subject come to conclusions that amount to “we can’t say for sure” shrugs. One of the most recent is surely known to Cameron because it was produced by the office of the Children’s Commissioner for England. In May, the commissioner released a report titled “Basically ... porn is everywhere,” which examined 276 research papers on teenagers and pornography."

NCAC (March, 2001). "White Paper Submitted to the Committee on Tools and Strategies for Protecting Kids From Pornography and Their Applicability to Other Inappropriate Internet Content.
"In 1986, the Surgeon General's Workshop on Pornography and Public Health concluded that there is no scientific basis to believe that minors are adversely affected by pornography. Indeed, it noted that many psychologists believe young children are unaffected by pornography because they lack "the cognitive or emotional capacities needed to comprehend it." In the end, these experts said, "it is really rather difficult to say much definitive about the possible effects of exposure to pornography on children." The more widely publicized majority report that same year of the Attorney General's Commission on Pornography (the Meese Commission) did not disagree. The Meese Commission acknowledged that its concerns about minors' access to pornography were based on morality, not science. In the Playboy Entertainment case, expert witnesses for both the government and Playboy testified at trial that there is no empirical body of evidence of harm to minors from exposure to pornography. [...] Dr. Richard Green, founding president of the International Academy of Sex Research and author of Sexual Science and the Law, testified that none of the available literature—including comparisons of the amount of erotica available in different countries, studies of sex offenders, laboratory experiments on pornography and violence, clinical experience worldwide, and research on people who as children had witnessed the "primal scene" of sexual intercourse—supports the notion that exposure to sexual explicitness is psychologically harmful to youth. In 25 years of clinical practice, Dr. Green had not encountered psychological problems stemming from pornography. The government in Playboy Entertainment initially attempted to establish harm to minors by offering testimony from Dr. Diana Elliott, who operated a clinic for abused children in California. The three-judge trial court rejected Dr. Elliott's testimony as weak, anecdotal, and "possibly misleading."8 Later, the government presented a new expert witness, Dr. Elissa Benedek, who opined that sexually explicit television might produce an assortment of harmful effects but acknowledged that she knew of no scientific literature or clinical studies supporting her belief, and that in her 30 years of psychiatric practice, nobody had come to her with a complaint about sexual images. The judges were unimpressed with Benedek's testimony. "We are troubled," they wrote, "by the absence of harm presented both before Congress and before us that the viewing of signal bleed of sexually explicit programming causes harm to children.""

Heins, M. (2001). Not in Front of the Children: "Indecency," Censorship and the Innocence of Youth. (p.11)
"The argument here is not that commercial pornography, mindless media violence, or other dubious forms of entertainment are good for youngsters or should be foisted on them. Rather, it is that, given the overwhelming difficulty in even defining what it is we want to censor, and the significant costs of censorship to society and to youngsters themselves, we ought to be sure that real, and not just symbolic harm results from youthful pursuit of disapproved pleasures and messages before mandating indecency laws, Internet filters, and other restrictive regimes."

[Editor: Robyn E. Blumner summed up this contribution].

Diamond, M., & Uchiyama, A. (1999). Pornography, Rape, and Sex Crimes in Japan. International Journal of Law and Psychiatry, 22(1), 1–22.
"Most frequently, as it was found in the 1960s before the influx of sexually explicit materials into the United States, those who committed sex crimes typically had less exposure to SEM in their background than others and the offenders generally were individuals deeply religious and socially and politically conservative (Gebhard, Gagnon, Pomeroy, & Christenson, 1965). Since then, most researchers have found similarly. The upbringing of sex offenders was usually sexually repressive, often they had an overtly religious background and held rigid conservative attitudes toward sexuality (Conyers & Harvey, 1996; Dougher, 1988); their upbringing had usually been ritualistically moralistic and conservative rather than permissive. During adolescence and adulthood, sex offenders were generally found not to have used erotic or pornographic materials any more than any other groups of individuals or even less so (Goldstein & Kant, 1973, Propper, 1972). Walker (1970) reported that sex criminals were several years older than non-criminals before they first saw pictures of intercourse"

"However, there are no specific child pornography laws in Japan and SEM depicting minors are readily available and widely consumed. [...] The most dramatic decrease in sex crimes was seen when attention was focused on the number and age of rapists and victims among younger groups (Table 2). We hypothesized that the increase in pornography [in general], without age restriction and in comics, if it had any detrimental effect, would most negatively influence younger individuals. Just the opposite occurred. The number of juvenile offenders dramatically dropped every period reviewed from 1,803 perpetrators in 1972 to a low of 264 in 1995; a drop of some 85% (Table 1). The number of victims also decreased particularly among the females younger than 13 (Table 2). In 1972, 8.3% of the victims were younger than 13. In 1995 the percentage of victims younger than 13 years of age dropped to 4.0%."

Cause or Confound?

The relationship between pornography viewing and "subsequent" behavior or well-being is a classic chicken and egg situation, in that causative direction can never be established when observing events in an uncontrolled, real-life scenario. This is already widely known in relation to television viewing. For example, a 1991 study found that of 391 junior high school students, those who watched sexual TV shows were more likely than those who viewed a smaller proportion of sexual content to have had sexual intercourse. The researchers were "unable to determine which came first—sexual intercourse or a proclivity for viewing sexual activity on television."^[11] Regarding pornography, it is even more likely that behaviors are correlated with viewing habits as a result of pre-existing character traits and ongoing socialization. This may be for a number of reasons:

Exposure to pornography is typically a self-directed act that takes place in private. A young person's socialization consists of numerous experiences, of which pornography consumption is but one tiny part.
In the modern world, free pornography is a highly categorized and subdivided medium, which can be immediately filtered by genre, fetish or other special interest. This, again, means that pornography exposure can be highly self-directed, and is likely to correlate with pre-existing interests and values, rather than influencing them.

Jeffrey Arnett, documenting a similar correlation between adolescents' reckless behavior and preference for violent music, identified "sensation seeking" as the confound that explained both the preference and the behavior. Arnett added that "adolescents who like heavy metal music listen to it especially when they are angry and that the music has the effect of calming them down and dissipating their anger."^[12]

At the personal level, some studies have attempted to eliminate confounds, finding that if anything, pornography only has a very mild effect on subsequent behavior.^[13] On a social scale, there is widespread correlational evidence linking wider availability of pornography with reductions in sexual offending, for example in Denmark, as documented in our Youth Erotica article, and Japan.^[14] This linkage between porn, sexual "responsibility" and celibacy is also supported by evidence following the advent of the internet.^[15]^[16] For example, men who offend typically have less exposure to pornography.^[17]

Some research on the causal relationship between pornography use and well-being:

Pirrone, D., Zondervan-Zwijnenburg, M., Reitz, E. et al. Pornography Use Profiles and the Emergence of Sexual Behaviors in Adolescence. Arch Sex Behav 51, 1141–1156 (2022). doi: 10.1007/s10508-021-02140-3
"We observed more robust associations with specific sexual behaviors for both boys and girls in the HP[high pornography] groups compared to the LP[low pornography] groups (e.g., masturbation and petting), perhaps because pornography leads to the acquisition of sexual scripts that may be activated in specific real-life social context [...] Another explanation, however, would be that both pornography use and these sexual behaviors reflect a relative stronger sexual interest or desire (Paul & Shim, 2008). In addition, the relatively strong relationship between masturbation and pornography consumption may result from the fact that pornography is often used for masturbatory purposes (Miller et al., 2019)."

Doornwaard, S.M., van den Eijnden, R.J.J.M., Baams, L. et al. Lower Psychological Well-Being and Excessive Sexual Interest Predict Symptoms of Compulsive Use of Sexually Explicit Internet Material Among Adolescent Boys. J Youth Adolescence 45, 73–84 (2016). DOI: 10.1007/s10964-015-0326-9
"As expected, most users of sexually explicit Internet material in our sample of Dutch male adolescents did not report any compulsive tendencies related to their use. Nonetheless, a small group of boys (i.e., between 4.2 and 11.2 %) did experience compulsive use symptoms on an occasional basis. [...] Furthermore, longitudinal analyses indicated that higher levels of depressive feelings and, again, excessive sexual interest predicted relatively higher scores on boys’ symptoms of compulsive use of sexually explicit Internet material 6 months later, with the former being the most consistent predictor"

Kohut, T., & Štulhofer, A. (2018). Is pornography use a risk for adolescent well-being? An examination of temporal relationships in two independent panel samples. PLoS ONE, 13(8), doi 10.1371/journal.pone.0202048
Cross-sectional evidence suggests that pornography use is related to lower mental wellbeing among adolescents but it remains unclear if changes in well-being are related to the dynamics of pornography use within this population. [...] After controlling for impulsiveness and family environment—factors that are unlikely to be influenced by pornography use — earlier levels of pornography use were not significantly associated with subsequent decreases in subjective well-being across gender and panel.

Subjective reactions

Studies into subjective reactions of children to sexual content are few and far between, and likely biased by bad questionnaire design, unwarranted focus on first exposure, and the childrens' own fear of censure/giving the "wrong" answer. The results are still surprisingly diverse in their nature, with most minors recalling a positive or neutral reaction to such material.

Smahel, D., H. Machackova, G. Mascheroni, L., Dedkova, E., Staksrud, K., Ólafsson, S. Livingstone and U. Hasebrink (2020). EU Kids Online 2020: Survey results from 19 countries, EU Kids Online, London School of Economics, London.
"being exposed to sexual images can be perceived both as a positive and a negative experience, depending on the context and the individual child. How sexual images are perceived can also be influenced by intentionality – the response to exposure due to seeking out sexual images could differ from unexpected exposure [...] in most of the countries, most of the children who saw some sexual image were neither upset nor happy (Ave = 44%), ranging between 27% (Switzerland) and 72% (Lithuania). In contrast, between 10% (Lithuania) and 40% (Switzerland) of the children were fairly or very upset (Ave = 22%), while feeling happy after seeing sexual images was reported by a similar number of children across the countries, ranging between 3% in Estonia and 39% in Spain."

McKee, Alan (2010) Does pornography harm young people? Australian Journal of Communication, 37(1), pp. 17-36.
"[...]researchers found that responses from children who accidentally see parents having sex include ‘amusement, giggling’ (Okami et al, 1998, p. 364). Similarly, in our interviews with people who had first encountered pornography before puberty, they tended to describe it as meaningless or funny (McKee, 2007c, p. 119). Such responses suggest that this is an area with which they are uncomfortable, and with which they aren’t ready to deal. However, there is no evidence of long term harm from this exposure."

[...]

"However, those interviewees who first encountered pornography in their early teens - when they were post-pubescent - were more commonly interested in its content. Several described the use of pornography at that age as a rite of passage, often consumed as a group, with an element of competition about who had the most material (McKee, 2007c, p. 119)."

[...]

"When we asked consumers of pornography to nominate the ‘effect’ that pornography had had on their attitudes towards sexuality, the top effect was making them more relaxed and comfortable about sex; and number eight was offering reassurance that their sexual identity (eg, for gay men) was acceptable (McKee, Albury and Lumby, 2007, p. 85)"

Why young people watch porn

Katerina Litsou, Paul Byron, Alan McKee & Roger Ingham (2021) Learning from pornography: results of a mixed methods systematic review, Sex Education, 21:2, 236-252, DOI: 10.1080/14681811.2020.1786362
“The most prevalent theme concerned young people’s use of pornography as a source of information to learn ‘how to have sex’. The articles frequently mentioned that inadequate sexual education and lack of sexual information about the mechanics of sex led people to engage with pornography. Pornography was mentioned by participants within these studies as being used for learning about sexual performance, positions and roles”

"According to this dataset, pornography use can offer useful information about the mechanics of sex, and this is particularly pertinent for young gay men. Many articles reveal that young people are often aware of the shortcomings of pornography as a source of information and guidance and that improvements to sex and relationships education are necessary"

McKee, Alan (2010) Does pornography harm young people? Australian Journal of Communication, 37(1), pp. 17-36.
"The interviewees made three points about this. Firstly they suggested that pornography can inform viewers about simple biological facts. Secondly, they said that a key educational element of pornography was to tell young viewers that it is OK to be interested in sex. A third theme was that pornography can educate viewers about the techniques for good sex (McKee, 2007c)."

Religiosity and Conservatism explain trends in porn users

In the 21st century, some literature (investigating the adult population) has established a relationship between the quantity of porn use and so-called "problematic/addictive porn use" or relationship problems. While it might be intuitive for conservatives to conclude that the porn caused the personal problems, and for libertarians to conclude that the personal problems led to porn use, another variable has been shown to explain this relationship. Absent socially conservative and religious values, there is no apparent relationship between such problems and porn use.^[18]

Excerpt Graphic Library

The Excerpt Graphic Library on Youth Sexuality has some useful information related to this topic. These can be accessed, saved and uploaded into shortform social media debates where character limits are in force.

Declining rates of sexual activity among youth (YRBS)
Various research on Teen Pregnancy correlational nonsense
Sexual Repression - effects on the young
Sexual Behavior in youth and its effects
Reading on child sexuality
Some reading on the effects of intimacy
Jane Rule on treatment of youth
NCAC: Justification for protecting children from porn has always been moral

Competences are also somewhat related:

Basic brain aging primer
Teen Brain research summary
Age chauvinism
BJ Casey
Joseph Bronski
Full Brain Size and adult-like competences in early childhood
Development of reasoning ability in early childhood (Moshman, 2005)
Early development of brain - Del Giudice
White and Gray Matter levels - Del Giudice (2017)
Bethlehem et al, 2022, brain volumes and matter levels by age
Giedd 1999 brain matter curves by age
Mills et al: Adolescent brains indistinguishable from adult. Variance in gray matter between individuals is far greater than any changes over time.
John Raven - Intelligence hits a peak in the mid teens, then plateaus and declines (the decline may have been at least in part due to poorer education in the interwar period).
John Raven - Intelligence hits a peak in the mid teens, then plateaus (note improvement in scores obtained in the 1970s)
Moshman on common fallacies of teen brain development
Moshman continued
Moshman continued
Laurence Steinberg (2008)
Epstein reviewed, plus other references - raw intelligence peak 13-15 y/o
2020 meta-analysis on the age of Thelarche (breast budding in girls - start of puberty). Similar for first period.
Conclusions of the aforementioned 2020 meta-analysis
Physical development - Tanner stages reached considerably earlier than commonly supposed
Physical development - Ages of pubertal development lower than commonly stated
Girls developing sexual features almost completely by 11