Almost two-thirds of pupils at Scottish secondary schools have experienced sexual harassment at or on their way to school in the past three months, according to a report.

In total, 65% of 13 to 17-year-olds reported experiencing some form of visual or verbal sexual harassment, such as sexual jokes, while 34% said they had experienced personally-invasive behaviour such as sexual touching, and 68% said they had experienced either type.

The study, led by the University of Glasgow, suggested a “gateway effect”, where personally-invasive behaviours involving contact were almost always reported by those also reporting more visual and verbal harassment.

About a quarter had been shown unwanted sexual messages or images (26%) and about a fifth (17%) had been described as gay or lesbian in a hurtful way.

Some participants said they felt unsure about whether they had experienced certain behaviours and, in focus groups, pupils were unsure about the acceptability of some behaviour.

The study of 638 pupils in June and November 2019 found a “strong association” between being a victim and a perpetrator of sexual harassment, with a fifth of those reporting they had been a victim of personally-invasive harassment – such as unwanted touching – saying they had also been a perpetrator of this (19.5%).

Boys were more likely to be perpetrators than girls, and older pupils were more likely to be victims of or perpetrate harassment than younger pupils. However, there were few gender differences in terms of how likely boys or girls were to be victims of harassment.

In focus groups of survey participants, pupils seemed unsure whether behaviours such as making sexual comments, calling someone “gay” or “lesbian” in a derogatory way, touching or grabbing someone or making sexual jokes were unacceptable or not.

Pupils were more likely to think certain behaviours, such as making sexual jokes, were acceptable among friends, especially friends of the same gender.

Factors such as the context of the behaviour, the pressure, persistence and physicality involved, as well as whether the perpetrator and victim knew one another, and the perceived intent of perpetrators, could all impact whether young people saw certain behaviour as acceptable or not.

The paper said that while young people perceive coercive or forced behaviour as unacceptable, “there are ambiguities around the acceptability of many behaviours generally regarded as representing sexual harassment” which require “complex judgments” at a life stage “marked by identity formation, exploration and initiation of intimate relationships”.

It adds that school-based interventions should recognise this by “adopting an approach which not only aims to increase knowledge of sexual harassment”, but also includes active discussion on how young people decide which behaviours are acceptable.

“They should also aim to develop understandings of how more serious, coercive and/or aberrant behaviours increase when less serious behaviours are perceived as normal and acceptable, so feeding into rape culture,” it adds.

Lead author Kirstin Mitchell, professor of social science and public health at the University of Glasgow’s MRC/CSO Social and Public Health Sciences Unit, said: “Sexual harassment is common, and often seen as normal among teenagers at school.

“Our study agrees with others in this respect, but, importantly, also highlights the uncertainties which teenagers may feel around whether many behaviours generally regarded as representing sexual harassment are acceptable or not.

“These results have implications for the design of school-based sexual harassment interventions which, if effective, could generate long-lasting changes in attitudes and behaviours.”

Scottish Education Secretary Shirley-Anne Somerville said: “Let me be clear, there is absolutely no place for harassment or abuse of any form – whether in the workplace, schools, in the home or in society.

“We are determined to ensure children receive high-quality relationships, sexual health and parenthood education in schools as an integral part of the health and wellbeing of the school curriculum in Scotland.

“We also continue to take forward a range of actions in schools to address gender-based violence and sexual harassment and we remain committed to developing national guidance for schools to help tackle sexual harassment and gender-based violence.”