Surprisingly, we are less likely to drink alcohol, smoke, gamble and eat takeaways. But the proportion of us classed as obese is still rising.
The survey also suggests that we are becoming more liberal. A solid majority (56 per cent), compared with only 38 per cent 10 years ago, support same-sex adoption.
The report is based on phone interviews with 520 people aged 14 and over a week, and more detailed written questionnaires returned by about half of those telephoned, since January 2001. Results are weighted to represent the wider population.
Auckland University of Technology public health professor Grant Schofield said the general picture of a more sedentary society and less social involvement was consistent with other surveys since the advent of television in the 1960s.
"Involvement in society beyond yourself is on the whole declining, and I guess more computer time reinforces that," he said.
The survey shows slightly smaller declines in most sociable activities in New Zealand than in Australia.
New Zealanders aged 14-plus who played sport in the past three months fell from 32 per cent in 2001 to 28 per cent last year.
In Australia the fall was from 32 per cent in 1998 to 23 per cent.
The activity that dropped most sharply in New Zealand was "taking a day trip in a car" - down from 54 per cent to 46 per cent, reflecting regular petrol prices that doubled from 104.5c a litre in 2001 to 205.8c last year.
Roy Morgan chief executive Michele Levine said the trend was away from pre-arranged family activities towards solo activities such as going to the gym. That was partly because both parents in most families now work.
"There was a tendency [in the past] to say when the husband comes home it's family time," she said. "Now if the woman in the family is juggling things, so is the man."
New Zealanders (57 per cent) are much more likely than Australians (39 per cent) to have shopped online in the past month, largely due to Trade Me.
And more than half (54 per cent) of all New Zealanders aged 14-plus, compared with 47 per cent of Australians, used Facebook in the past month.