Next year, the UK government will require internet service providers to block pornography from customers' computers and phones unless they choose to opt in.

University of South Australia academic Lesley-Anne Ey said it was too easy for children to access internet pornography.

Mrs Ey said US and Australian research found that the median age for boys to access pornography was 11, and a majority of boys and girls had viewed it by age 13. 

She said pornography shaped their sexual identity.

``They are basing their understanding of sexual relationships on hard-core pornographic images,'' Mrs Ey said.

``It is limiting their understanding of what intimacy is, and giving them negative attitudes towards women.

``They see girls as sexual commodification more than partners . . . (and) girls think that they should be sexually available and are there to please a man.''

Digital Tasmania spokesman Charles Gregory said internet filters were not 100 per cent effective and raised censorship issues. ``Usually these sorts of systems are not very effective as the sites are always changing and it is hard to block all content,'' Mr Gregory said.

``Some of these filters block information on abortion, or sex education, so it is a slippery slope as to what content is good and what is bad, and different people have different moral centres.''

Child Health Association of Tasmania Northern co-ordinator Tanya Zaadstra said it could be extremely distressing for children to see graphic and sometimes exploitative internet pornography.

``Parents try to monitor these things but it is very difficult to monitor all the time,'' Mrs Zaadstra said. ``Anything that is going to limit access and protect children (from porn) is worth looking at.''