A study of what motivates people in Australia to become terrorists has found friends and family are bigger factors than extremist material posted online.

The four-year project, carried out by Monash University and police, involved more than 100 interviews with extremists in Australia, Indonesia, Europe and North America.

Researchers also spoke to counter-terrorism experts to try to identify ways to prevent violent extremism.

They found Australian militants and terrorists frequently consulted and consumed online extremist material but other factors were more important in radicalising them.

Social networks of friends and family, including contact with people who had fought overseas or been to terrorist training camps, had a stronger influence.

Researcher Debra Smith says the way people join terrorist groups is similar to the way people get involved in other anti-social behaviour, such as drug use.

"It can be very normal people going through very normal processes, but they just happen to get emotional connection to somebody who is involved in violence," she said.

"It can just be frankly bad luck that they they happen to be involved with somebody who perceives violence as legitimate."

Another researcher who worked on the study, Shandon Harris-Hogan, says while terrorism is a relatively small problem in Australia, some people remain attracted to extremism.

"In Australia we haven't really had any example of individuals being recruited into networks," she said.

"We see the dynamic actually works the other way - that it's often people seeking out these kind of movements and individuals and drawing their own sort of social groups together, rather than anybody being actively recruited into terrorism.

"We need to always be alert to the possibility of Ander Breivik or Wade Michael Page from a right-wing ideology actually emerging from within the community."

Heavy-handed policing was found by the report to be a less effective response to countering radicalism than early intervention.

The research showed the prospect of radicalising individuals actually increased, rather than reduced, when "hard" responses were used.

Averting vulnerable people before their views were fully formed was found to better help prevent the slide into criminal behaviour.