After early wins in areas such as persuading people to pay fines on time, or cut down on fizzy drinks, the so-called behavioural scientists are raising their sights, said Dr Rory Gallagher, head of the Behavioural Insights (BI) Team in Australia.

"We are now looking at corruption at an international level, we are dealing with issues like anti-microbial resistance … pretty complex topics," he said.

"So I would hope that in a couple of years' time we could start to get into things like end-of-life – very pressing issues, but very amenable hopefully to our methods."

The methods include testing to see how the nudges, or unconscious pokes and prods, subtly influence people's decisions, pushing you towards what it believes are your (or society's) best interests, exploiting the biases and tics of the human brain uncovered by research into behavioural psychology.

BI grew out of the "Nudge Unit" in David Cameron's prime ministerial office in the UK, and is now exporting behavioural science to civil services around the world.

It is advising Australia's federal and state governments on experimental nudges that are already influencing Australians to exercise more regularly, get breast cancer check-ups and attend hospital appointments.

Currently in NSW it is conducting trials on behavioural nudges to keep commuters out of central Sydney at peak times, and to reduce domestic violence.

"Some of the most interesting work we are doing at the minute is around domestic violence," Dr Gallagher said. They are looking at how to simplify forms used in the justice system, and adding 'behavioural messaging" to help reduce violence.

"We are looking now at other more deep behavioural change programs aimed at defendants to reduce reoffending."

Dr Gallagher said BI's UK arm had discussed how techniques might be applied to living wills.

Living wills, also known as advanced care directives, set out a person's wishes over what kind of treatments they want – or don't want – should they become incapacitated and terminally ill.

However some hospitals and doctors have found it difficult to discuss living wills with patients and families, who are suspicious they are signing their own "death warrant".

"My wife's a palliative care doctor and so we've had several conversations about how important those initial conversations and the framing of some of those decisions are," Dr Gallagher said.

"There's huge human capital, personal, emotional and financial costs to those sorts of decisions and I would say the system is definitely not working as well as it could do."

Many of BI's successes in Australia have come in the health field.

In the last year the organisation ran a trial at Victoria's Alfred Hospital adding 20 per cent to the price of high-calorie, sugary drinks in half of the hospital's vending machines.

The trial worked: 44 per cent of drinks bought from machines with the price hike were high-calorie, compared with 49 per cent of drinks bought from unaffected machines.

This result would inform policy debates in Australia and in the UK, Dr Gallagher said.

"People were considering whether we should have a sugar tax but there's very little evidence on what price increases may do to consumption," he said.

There were signs that people were not just switching to low-calorie alternatives, but all the way to water, Dr Gallagher said. "We weren't expecting that."

But overall sales stayed the same, so the retailers weren't out of pocket.

"That's really important for us to know and to make the case to policy makers that a sugar tax could not only achieve our objective but also wouldn't economically harm retailers."

BI also worked with Lendlease, who gave their employees FitBit devices to measure their physical activity.

They compared what sort of feedback was most encouraging, and found an extra 700 steps a day were taken by people who got personalised feedback on their performance, rather than just being ranked in a leaderboard. The effect was most pronounced in those who'd been the least active before the experiment.

"Relatively subtle prompts can lead to significant changes in outcomes," Dr Gallagher said.

In NSW, BI worked with St Vincent's Hospital improving attendance at outpatient appointments.

It found that sending a text message saying "if you attend, the hospital will not lose the $125 we lose when a patient does not turn up" resulted in 20 per cent fewer missed appointments.

The simpler, but more negative message "If you do not attend, the hospital loses $125" was not as effective.

BI is working with the NSW Department of Premier and Cabinet on other nudge experiments, in areas such as return to work, childhood obesity and rental arrears in social housing.

Dr Gallagher said he couldn't yet reveal details, but the report said they showed "some impressive wins but also, as would be expected, that not everything has worked".

In Australia BI has doubled in size in the last year – in terms of personnel and income.

Behavioural interventions are becoming a mainstream pursuit of civil servants in the UK and in other countries including Australia, Singapore and the US, BI said as it issued its annual update report on Wednesday night.

They are being applied in education, policing, charity, traffic offences, tax collection and health.

Ben Gummer, Minister for the UK's Cabinet Office, said Behavioural Insights was "now a central part of how government goes about its business", growing rapidly from its establishment in 2010.

And Cabinet Secretary Sir Jeremy Heywood, head of the British civil service, said the scale and level of ambition of behavioural science was rising, used in almost every government department.