Classification chiefs have ordered new research into on-screen sexual violence following the controversy over so-called torture porn films including The Human Centipede II.
The British Board of Film Classification (BBFC) cut more than two and a half minutes from the film about an obsessed horror movie fan who staples people together for kicks before giving it a certificate last year.
Around the same time it banned another film - The Bunny Game - about a prostitute kidnapped and sexually abused by a trucker.
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Both films, and other controversial titles including A Serbian Film and Lars von Trier's Antichrist, have been shown to carefully selected focus groups as part of the research.
BBFC director David Cooke said: "What we're doing is getting the public on a fairly in-depth basis to look at some of this difficult material in controlled circumstances so they do have debriefing or counselling available because it's not a very pleasant thing to do".
The organisation said the research, which is carried out by Ipsos-MORI, would help "determine what the British public today believes is potentially harmful and therefore unacceptable for classification".
The BBFC carried out similar research 10 years ago.
The new research will be completed this year and published later.
Mr Cooke said the BBFC would also carry out a large public consultation next year, involving between 8,000 to 10,000 people, examining attitudes to on-screen behaviour including bad language.
He said some of his "continental colleagues" thought the BBFC attitude to swearing was "crazy" but said research found people were still concerned about it.