SYDNEY, Dec 7 - A discussion paper on the impact of pornography has been released by the Australian Institute of Family Studies, which reveals just under half of all children aged nine to 16 have viewed pornography.

The paper says there is a "growing evidence base" showing that adolescents' use of pornography can negatively influence their knowledge about sex, safe sex practices, gender roles, and could lead them to have unrealistic expectations about sex.

"In Australia, 44 per cent of children aged nine to 16 years old had encountered sexual images in a 12 month period. Of these, 16 per cent had seen images of someone having sex," Institute Director Anne Hollonds said.

Responses to the exposure varied, however the research showed more young girls expressed shock or distress compared to the boys. The males were more likely to find pornography amusing or exciting.

Hollonds says exposure to pornography for some can be accidental as they turn to the internet to search online for information on sexual health, relationship or medical advice.

In the absence of quality sex education, parents are being asked not to underestimate the impact pornography could have on adolescents.

"The content of pornography may reinforce double standards of an active male sexuality and a passive female receptacle," AIFS Senior Research Fellow, Dr Antonia Quadara said.

"Exposure to pornography can shape young people's expectations about sex, for example about what men find pleasurable, what they expect their partners to do and how consent is negotiated. It also depicts sex that undermines public health messages about safe sex and condom use," Quadara said.

Quadara said previous research has also shown evidence of an association between consuming pornography and boys perpetrating sexual harassment.

"Male adolescents who view pornography frequently were more likely to view women as sex objects, strengthening attitudes supporting sexual violence against women."

AAP