The British Board of Film Classification has rewritten its guidelines on horror movies after consulting members of the public.

New rules on classification will come into force next month, partly inspired by the large number of complaints made over the Daniel Radcliffe chiller The Woman in Black two years ago. BBFC assistant director David Austin told the BBC that filmgoers were increasingly concerned over the "tone" and "theme" of horror movies, as well as the amount of gore shown on screen.

The Woman in Black, a ghost story, was awarded a 12A certificate by the board, prompting 134 complaints, the largest number in 2012. In 2011, the most complained-about rating was the 15 handed to the Oscar-winning psychological thriller Black Swan, which featured scenes of self harm.

"We do this consultation every four years," said Austin. "We show the general public the most controversial films from that time, and ask: 'Do we get it right?'

"We picked the most complained-about films of the past four years, The Woman in Black and Black Swan, to see if those films were dealt with properly via classification.

"With horror films, we found people more concerned about things such as loss of a child and supernatural themes. We are highlighting supernatural themes specifically for the first time. Black Swan featured depiction of self-harm, which the public said they wanted us to be very careful about."

Austin said that the 12A certificate was not universally understood. A quarter of people did not know what it meant, he said.

According to the BBFC website: "12A means that anyone aged 12 or over can go and see the film unaccompanied. The A stands for 'accompanied' and 'advisory'. Children younger than 12 may see the film if they are accompanied by an adult (eg someone over the age of 18), who must watch the film with them."

The new guidelines, introduced after the consultation involving 10,000 people, will pay more attention to the impact of gore and strong visuals, according to the BBC. The sexualisation of young women will be a special focus, and language in U-certificate movies could be tightened up. On the other hand, there could be more flexibility when it comes to strong language in films given a 15 certificate.

The BBFC has defended its certification of The Woman in Black, suggesting that the vast majority of participants in its new study agreed with the 12A rating.