AUT Professor Grant Schofield, who led the New Zealand study, blames our love affair with cars.
"Auckland still has more cars per person than Los Angeles," he says.
"Urban design over the last 30 years has been the residential cul-de-sac and single-use neighbourhoods where you get in your car to go anywhere. What would you expect, compared to countries where they don't do that?"
A 2013 "Kids in the City" study led by Massey University Professor Karen Witten, which interviewed 150 Auckland children and their parents, lyrically describes close-knit neighbourhoods that have been lost.
"There was near universal agreement among our study parents that their children had less freedom to explore neighbourhood environments than they had experienced as children," the paper says.
"Recollection of their childhoods commonly included knowing and being known by neighbours, moving freely in and out of friends' and relatives' houses and roaming outdoors in groups of mixed-aged siblings, cousins and friends, returning home when darkness fell or they were called for meals or tasks.
"However, for their children's lives ... close monitoring and surveillance of out-of-school time was commonplace. Safety concerns were the prime drivers of these practices."
An online survey last year of people who joined a new website, neighbourly.co.nz, also found that 42 per cent of people know fewer neighbours than they did when they were growing up. Only 12 per cent know more neighbours now than they did as children.
This doesn't mean we're socially isolated. Another AUT professor, sociologist Charles Crothers, cites a world values survey showing 87 per cent of us belong to some kind of social group such as a sports club or charity - the fourth-highest rate in the world after three African nations.
He suspects Dr Schofield's survey may have found much lower neighbourhood links by using an online sample - "exactly the people staying at home hunched over their internet access and NOT relating to neighbours!" The 30 European countries did their surveys face-to-face.
But Dr Schofield says his sample, drawn from a panel used by market researchers TNS Global, was chosen to be representative of the NZ population. "The magnitude of the difference between the best European countries and us is like four- or five-fold," he says. "You can hardly explain that away."
The drivers
Cars
Experts agree that our growing use of cars is a big part of the story. On the latest World Bank data, our 708 vehicles for every 1000 people in 2011 was actually less than in Australia (723) or the United States (809), but above all the European countries in Dr Schofield's comparison except Iceland.
Taking people off footpaths and bus stops and into cars reduces the chances of meeting the neighbours.
It also makes the streets more dangerous, which means children are less likely to be allowed out, so they are also less likely to meet each other.
Working mothers
Mothers, Dr Witten says, "used to be the glue of the neighbourhood". In 1976 only 40 per cent of women aged 20 to 64 were in or seeking paid work; today it's 73 per cent, higher than in 25 of Dr Schofield's 30 European comparators.
"Fewer women at home or out and about in the neighbourhood during the day was linked to parents' talk of declining neighbourhood-based relationships," Dr Witten writes.
Mobility
More renting, more casualised work and globalisation are all pushing Kiwis to move house more often than in the past, and more than in any comparable country. When the question was first asked in the 1971 Census, 39 per cent had moved in the past five years. By 2013 it was 51 per cent, compared with 42 per cent in Australia and 35 per cent in the US.
Inspiring Communities' Denise Bijoux says: "If you don't stay in one place, you don't make the effort to put the connections out."
Competition
Dr Witten says parents are now increasingly likely to drive their children out of the local area to "better" schools and after-school activities. "Part of that reflects parents believing it's a competitive world out there."
Urban design
Dr Vivienne Ivory of Otago University's "neighbourhoods and health" project agrees with Dr Schofield that cul-de-sacs, designed by planners to slow cars, have actually deterred people from walking what is now a long way around to shops and other amenities. Paths were built as short-cuts, but fearful neighbours have often built high walls beside them, making them dark and dangerous.
5 steps to meet the neighbours
• Bake or make something for your neighbour and drop it off.
• Say hello to a neighbour you don't know.
• Collect your immediate neighbour's contact details.
• Take extra garden produce to your neighbour (too many feijoas anyone ... ?).
• Invite your neighbour over for a cup of tea and a chat.
- Source: www.neighboursday.org.nz
Local networks give rise to a sense of belonging
Last year's survey by the Neighbourly website uncovered a widespread yearning: 85.5 per cent of people said they wanted to know their neighbours better. The site has grown fast since it started last June and signed up its 100,000th member this month.
"We have a network where, if there is a situation in a suburb where there is a crime and safety issue or a need to help with shifting furniture, there is now someone you can go to to get help," says co-founder Casey Eden.
"We've found lost cats, lost chickens, lost cars, lost jewellery. We've done beach clean-ups. In my area, St Heliers, someone needed some lavender for a wedding, and the post had oodles of people saying, 'I've got lavender in my garden'."
The site, which aims to make money through commercial sponsorship, fills a real gap. Even though we may have friends and relatives around the world, Dr Vivienne Ivory says we still need to feel grounded somewhere.
"Being attached to a place and feeling that is part of my identity is well recognised as a contribution to ... wellbeing," she says.
Her research shows that strongly cohesive neighbourhoods are associated with good mental health for women, although not for men.
She believes children need neighbourhoods where other adults are looking out for them so they can take the first steps to independence - literally to walk and bike around the local area before they are let loose as teenagers to drive.
Dr Grant Schofield's wellbeing index also shows that, after adjusting for all other factors, those who feel close to people in their area are 2.6 times more likely to have high wellbeing than those who don't feel close to their neighbours.
Dr Ivory says planners can encourage local interaction through wider, more open pathways, better public transport, siting parks and playgrounds where they are visible from the street, providing seats and toilets, and locating shops and other facilities in the centre of every suburb, rather than on the fringes as at Westgate in West Auckland.
Massey Matters, in the suburb adjoining Westgate, has recognised the schools in its area as its natural hubs. Manager Tracy Watts says it is transforming disused dental clinics into mini-community centres at Colwill, Royal Rd and Lincoln Heights Schools, and has just opened a purpose-built community hub at West Harbour School.
Dr Karen Witten laments a trend for schools to close after 3pm for fear of vandals, and praises Freemans Bay School for staying open at nights and weekends as a meeting place.
Its principal, Sandra Jenkins, says the school serves many children living in flats who have nowhere else to play.
Neighbours Day this weekend is an opportunity to hold a street party, invite the neighbours over for a barbecue, or just say hello. Project manager Kimberley Cleland says 602 neighbourhoods had registered plans by yesterday to run everything from family fun days to backyard cricket games plugging into World Cup fever.
