Professor Newbold said the type of female imagery available to women and young girls created an increased likelihood of violent offending among females.
"The media is full of women who are incredibly sexy and good-looking, and who are mentally and physically tough. The constant exposure of young girls and women to this type of image creates an association between being beautiful and powerful, and being at the top."
In the latest incident of female-instigated violence, two women were arrested last Saturday after a group of wedding guests was attacked outside a shopping centre in Mount Maunganui.
Last year, a mother and daughter were sent to prison after using cellphones to premeditate an attack on an unwitting woman they lured into a Welcome Bay bus stop. The two women, assisted by a half-sister and male youth, attacked the woman and inflicted serious injuries.In January a mother and daughter were arrested after allegedly attacking Countdown supermarket staff in Rotorua. The video footage of the scuffle was uploaded to YouTube.
Female youth violence researcher Donna Swift said there were more cases of girls fighting and put footage of themselves on the internet and Facebook.
Dr Swift is head researcher of Girls Project - a two-year study of 3500 Year 10 students that is investigating the reasons behind violent behaviour amongst girls.
She said that in her experience, many young women turned to violence because it was normalised in their own homes and communities.
"Girl fighting often is highly sexualised by the media and males themselves," she said.
'One of the most startling we found amongst New Zealand female youths was the change in behaviour exhibited by girls when they reached the ages of 15 and 16 years."
"They either move away from this type of [violent] behaviour or they become more sophisticated in it," added Dr Swift.
"For those that don't move away from it, it can become part of their sense of identity."
Les Simmonds, Relationship Services clinical leader for Bay of Plenty and Gisborne, said there was little doubt young women were more violent these days.
"Adolescent girls are becoming more violent but, the truth of it is that it is a minority group and in that small minority, it's more severe," Mr Simmonds said. "If you go back years and years ago women were socialised to be a certain way in society and now women are socialised to be more equal and fill a lot of roles previously filled by males.
"That's hugely positive but you have some of the negative things that come as part of that."
A youth police officer based in Tauranga, Rob Everitt, said the number of violent incidents involving female offenders was increasing.
"We get more and more complaints as time goes on and there are definitely more assaults being committed."
Mr Everitt also said the severity of violent incidents involving females had also worsened, as many had taken to more aggressive physical behaviour such as punching and kicking compared to scratching and hair-pulling.
Both Dr Swift and Professor Newbold agreed the increasing trend highlighted larger social issues.
"A large part of it is the circumstances in which these children grow up in. In order to address girls violence, these issues must be dealt with using preventative programs," said Dr Swift.
* Some recent female assaults
- March 24: Two women were arrested after a group of wedding guests was attacked outside a shopping centre in Mount Maunganui.
- December 2011: Eve Campbell, 50, and daughter Cherylly Campbell, 30, allegedly attacked Countdown supermarket staff in Rotorua
- August 2011: Four girls and one boy, some as young as 13 and 14 assaulted a Hamilton man. He was stripped, beaten and held captive.
8 June 2011: A drunk teenage girl allegedly hit a 73-year-old Auckland dairy owner in the head with a hammer to steal chocolate bars and cigarettes.
8 June 2011: Nancy Stevenson, 17, and Fern Dixon, 18, attacked a 14 year old girl in a Westport skatepark.
